Impact of soft contact lenses for digital devices on visual performance, tear film, accommodative response and dehydration in young adult subjects: a pilot study

Universidade do Minho Escola de Ciências Avelino Nelson Filipe Mazuze maio 2021 Impact of Soft Contact Lenses for Digital Devices on Visual Performance, Tear Film, Accommodative Response and Dehydration in young adult subjects: A Pilot Study Avelino Nelson Filipe Mazuze Impact of Soft Contact Lenses for Digital Devices on Visual Performance, Tear Film, Accommodative Response and Dehydration in young adult subjects: A Pilot Study UMinho|2021 Universidade do Minho Escola de Ciências Avelino Nelson Filipe Mazuze maio 2021 Impact of Soft Contact Lenses for Digital Devices on Visual Performance, Tear Film, Accommodative Response and Dehydration in young adult subjects: A Pilot Study Trabalho efetuado sob a orientação do Professor Catedrático José Manuel González-Méijome e da Professora Doutora Rute Juliana Ferreira Macedo de Araújo Dissertação de Mestrado Mestrado em Optometria Avançada ii DIREITOS DE AUTOR E CONDIÇÕES DE UTILIZAÇÃO DO TRABALHO POR TERCEIROS Este é um trabalho académico que pode ser utilizado por terceiros desde que respeitadas as regras e boas práticas internacionalmente aceites, no que concerne aos direitos de autor e direitos conexos. Assim, o presente trabalho pode ser utilizado nos termos previstos na licença abaixo indicada. Caso o utilizador necessite de permissão para poder fazer um uso do trabalho em condições não previstas no licenciamento indicado, deverá contactar o autor, através do RepositóriUM da Universidade do Minho. Licença concedida aos utilizadores deste trabalho Atribuição-NãoComercial-SemDerivações CC BY-NC-ND https://creativecommons.org/licenses/by-nc-nd/4.0/ iii AKNOWLEDGEMENTS Aos meus pais, Filipe ( in memoriam ) e Amélia pela oportunidade da vida e por despertarem em mim o mundo das vogais e das consoantes no tremor das dificuldades. A minha noiva Elisa pela paciência, companheirismo e apoio ao longo desta jornada. Aos meus irmãos Luis, Carmecinio e Hélder queria profundamente manifestar a minha gratidão e o reconhecimento do vosso papel na minha formação acadêmica. Em vós me inspirei bastante para que cá chegasse. Ao Professor José Manuel González-Méijome. Pela sapciência e generosidade (marca da sua sabedoria), mas acima de tudo pelo incentivo e apoio moral fornecido durante esta orientação. Sou eternamente grato por toda a ajuda, partilha de conhecimentos ao longo destes dois anos e meio. Meu muito obrigado A Professora Rute Juliana Ferreira Macedo de Araújo. Pelo esmero (marca da sua sabedoria) teórico e analítico, e por partilhar o seu conhecimento e experiência em todas as fases deste projeto. Obrigado pelas sugestões fornecidas durante esta orientação. Ao Jeremias Chone, à Tomasina F. Nckuaki e Gisela Ferreia Huelo. Pelo companheirismo, amizade e por partilhar convosco estes momentos ímpares das nossas vidas. Ao Jorge Texeira, Leida Taveres e a querida “mãe” Diolinda pelo acolhecimento desde a minha chegada à Portugal e pela amizade durante esta jornada. Ao Grupo e Laboratório de Investigação em Optometria Clínica e Experimental (CEORLab), pela partilha de experiências. Um especial agradecimento ao Professor João Manuel Maciel Linhares, António Queirós Pereira e Jorge Jorge por toda ajuda ao longo destes anos dentro e fora deste projeto. Um especial agradecimento a Ana Amorim por toda ajuda ao longo deste projeto. Ao Camões – Instituto de Cooperação e da Língua, I.P e o Instituto de Bolsas de Estudo de Moçambique pela bolsa de estudos. Sem este apoio este projeto não existiria. Um especial agradecimento a Universidade Lúrio pelo apoio fornecido durante esta jornada. Aos meus colegas de Mestrado porque partilharam este caminho comigo e sempre estiveram disponíveis para ajudar. Aos voluntários que participaram nesta pesquisa, pela simpatia e disponibilidade em submeterem-se aos procedimentos experimentais. Enfim, meus sinceros agradecimentos a todas aquelas pessoas que de forma direta ou indireta contribuíram na materialização desta pesquisa. Avelino N. F. Mazuze, May 2021 iv STATEMENT OF INTEGRITY I hereby declare having conducted this academic work with integrity. I confirm that I have not used plagiarism or any form of undue use of information or falsification of results along the process leading to its elaboration. I further declare that I have fully acknowledged the Code of Ethical Conduct of the University of Minho. v ABSTRACT Impact of Soft Contact Lenses for Digital Devices on Visual Performance, Tear Film, Accommodative Response and Dehydration in young adult subjects: A Pilot Study The purpose of this study was to investigate the effect of soft contact lenses (CLs) claimed to be beneficial for use of digital devices on visual performance, accommodative response as well as tear film and dehydration in young adult subjects. Seven young-adult myopes with mean age of 25.71±3.40 years wore two designs of CLs for digital devices - Biofinity Energys (Comfilcon A) and Bausch + Lomb ULTRA (Samfilcon A) - for a week each in a randomised single-masked cross-over study. Visual performance was measured with high and low-contrast visual acuity at distance (ETDRS visual charts), optical quality (aberrometry), light disturbance (LD) measured with a Light Disturbance Analyzer, tear film (dynamic cornal topography), accommodative response (badal optometer coupled with an openfield autorrefractometer), quality of vision (Quality of Vision questionnaire) and comfort were evaluted at lens dispensing visit (LDV) and after one week of wear. CLs dehydration was evaluated in vitro and ex vivo using a gravimetric method. A single vision contact lens was used as control device. The results showed that no significant differences in the level of visual performance achieved with both types of CLs for digital devices in comparison with Control lens (p > 0.05, Friedman test). Concerning optical quality, significant differences were found for coefficients Astig Obli, Horizontal COMA, 4th and 6th order spherical aberration with CLs tested (all p≤0.03). The irregularity parameter of LD showed significant differences in monocular condition between CLs tested (p=0.028). Tear Film Surface Quality (TFSQ) Index and TFSQ Area increase significantly with CLs tested compared to baseline (p<0.05, Friedman test). Auto Tear Break-Up Time (BUT) was significant higher at Baseline than CLs tested (p<0.05, Friedman test). Accommodative response, comfort and QoV did not change significantly (p>0.05, Friedman test). CLs dehydration rates ( vitro and ex vivo ) did not change significantly (p>0.05, Unpaired T-test and ANOVA). The findings of this study suggest that soft CLs for digital devices offer similar visual quality outcomes and clinical performance compared to the Control lens. Importantly, change in tear film stability, comfort score and QoV were not statistically significant, but were clinically significant. Thesepreliminary outcomes should be confirmed with a larger sample size. Keywords: accommodative response and tear film instability; contact lenses; digital devices; visual performance.. vi RESUMO Impacto das lentes de contato para dispositivos digitais no desempenho visual, filme lacrimal, resposta acomodativa e desidratação em jovens adultos: um estudo piloto O presente estudo teve como objectivos investigar o impacto das lentes de contato (LC) destinadas ao uso com dispositivos digitais na performance visual, resposta acomodativa, bem como filme lacrimal e desidratação em adultos jovens. Sete míopes adultos jovens (25,71 ± 3,40 anos) foram adaptados dois desenhos de LC para dispositivos digitais - Biofinity Energys (Comfilcon A) e Bausch + Lomb ULTRA (Samfilcon A) por uma semana, num estudo cruzado aleatório e simples cego. O desempenho visual (cartas visuais de ETDRS), qualidade óptica (aberrometria), distorção luminosa (LD) medida com um analisador de perturbação da luz, filme lacrimal (dynamic cornal topography), resposta acomodativa (badal optometer acoplado a um autorrefractómetro de campo aberto), qualidade de visão (Questionário de Qualidade de Visão) e conforto foram avaliados na visita de dispensa (LDV) e após uma semana de uso. A desidratação das (LC) foi avaliada in vitro e ex vivo, utilizando o método gravimétrico. Uma lente de contacto de visão única foi utilizada como dispositivo de controlo. Os resultados mostraram que não houve diferenças significativas na performance visual alcançado com ambos os tipos de LC para dispositivos digitais em comparação com as lentes de controlo (p > 0,05, teste Friedman). Relativamente à qualidade óptica, foram encontradas diferenças significativas para os coeficientes Astig Obli, Horizontal coma, 4th and 6th ordem de aberração esférica na visita de dispensa e de acompanhamento (todos p ≤ 0,03). O parâmetro de irregularidade da LD mostrou diferenças significativas em condição monocular entre lentes. Os Índices Tear Film Surface Quality (TFSQ) e TFSQ Área aumentam significativamente da baseline em comparação com as lentes testadas (p < 0,05, teste Friedman). O tempo de ruptura do filme foi mais elevado na Baseline do que nas lentes testadas, com diferenças significativas entre a Baseline em comparação com as lentes testadas (p <0,05, teste Friedman). A resposta de acomodativa, conforto, QoV e a desidratação (vitro e ex vivo) não foram estaisticamente significativamente (p > 0,05). Os resultados deste estudo sugerem que as LC para dispositivos digitais oferecem resultados de qualidade visual e desempenho clínico semelhantes em comparação com as lentes de controlo. É importante ressaltar que as mudanças na estabilidade do filme lacrimal, conforto e QoV não foram estaticamente significativas, mas foram clinicamente relevantes. Esses resultados preliminares devem ser confirmados com amostras de tamanho maior. Palavras-chave: desempenho visual; dispositivos digitais; lentes de contato; resposta acomodativa e instabilidade do filme lacrimal.. vii TABLE OF CONTENTS ABSTRACT ......................................................................................................................... v RESUMO ........................................................................................................................... vi GLOSSARY OF TERMS & ABBREVIATIONS ......................................................................... x LIST OF FIGURES ............................................................................................................. xv LIST OF TABLES ............................................................................................................. xix 1. INTRODUCTION ..................................................................................................... 2 1.1 Research rationale and justification of study ..................................................... 2 2. LITERATURE REVIEW ............................................................................................ 6 2.1 Methods of the bibliographic search .................................................................. 7 2.2 Symptomatology associated with use of digital devices ..................................... 8 2.3 Symptom-inducing risk factors ......................................................................... 10 2.3.1 Dry eye and digital devices ............................................................................................12 2.4 Effects of digital devices use on vision ............................................................. 14 2.4.1 Visual Performance .......................................................................................................14 2.4.2 Accommodation ............................................................................................................16 2.4.3 Binocular Vision ............................................................................................................18 2.4.4 Tear film .......................................................................................................................20 2.5 Management of visual and ocular symptoms related to digital devices ............ 24 2.5.1 Visual Ergonomics ........................................................................................................25 2.5.2 Management of refractive error .....................................................................................26 2.5.3 Management of binocular vision anomalies ...................................................................29 2.5.4 Management of CVS-Related Dry Eye ............................................................................29 2.6 Contact lenses and use of digital devices ......................................................... 31 2.6.1 Impact of contact lens on ocular surface and use of digital devices ................................31 2.6.2 Contact lenses and dehydration process .......................................................................33 3. AIMS AND HYPOTHESIS OF THE STUDY .............................................................. 36 3.1 Problem formulation ........................................................................................ 36 3.2 Hypothesis ....................................................................................................... 37 xiv VA: Visual Acuity VDT: Vídeo Display Terminal VDU - Visual Display Units URE: Uncorrected Refractive Error xv LIST OF FIGURES Figure 1-1 - Flowchart showing the organization followed in the current dissertation. ......................... 4 Figure 2-1 – Internet users in the World in 2020. Source: Internet World Statshttps://www.internetworldstats.com/stats.htm, accessed in January of 2021. .................................... 6 Figure 2-2 - Publication rate (yearly) related to computer vision syndrome or digital eyestrain as retrieved by the National Library of Medicine search engine (PubMed) by January 2020, using keywords: “computer vision syndrome OR digital eyestrain”. Source: https://www.ncbi.nlm.nih.gov/pubmed/, accessed in January 2020. ................................................. 8 Figure 2-3 – Visual and ocular symptoms associated with use of digital devices. Reproduced from Coles-Brennan et al. (2019) .............................................................................................................. 10 Figure 2-4 - Factor analysis of visual symptoms related to CVS in 520 office worker. Two dimensions are clearly identified, namely factor 1 (related to dry eye) and factor 2 (associated with ocular accommodation). SBL, sensitivity to bright light; HA, headache; ES, eyestrain; Discomfort, eye discomfort; TE; tired eyes; Burning, burning eyes; DE, dry eyes; BVD, blurred vision looking into the distance; BVvC, blurred vision while viewing the computer; Refocus: slowness in refocusing . Data from Portello et al . (2012)......................................................................................................................... 11 Figure 2-5 - Incidence of the ocular symptoms after 4h of computer task in 20 subjects. Data from Guillon et al . (2004).......................................................................................................................... 14 Figure 2-6 - Change in visual acuity at four lighting colors in 10 subjects. Data from Lin et al. (2008). ........................................................................................................................................................ 15 Figure 2-7 - Mean values of accommodative response at a viewing distance after 30 mints of computer task in 20 subjects. Data from Collier and Rosenfield, (2011). ........................................... 18 Figure 2-8 - Mean values of associated phoria in prism dioptres (PD) at a viewing distance after 30 mints of computer task in 20 subjects. Data from Collier and Rosenfield, (2011). .............................. 20 xvi Figure 2-9 - Schematic representation of trilaminar structure of the tear film composed by an outer lipid layer, an intermediate aqueous layer, and an inner mucous layer. Source: https://www.refreshbrand.com/dryeye/dry-item/tear-film, accessed in January 2020. ..................... 21 Figure 2-10 - Correlation between the total symptom score plotted and percentage of blinks that were deemed incomplete during the course of a 15min computer task performed at a viewing distance of 50cm in 21 subjects. Data from Portello et al. (2013). ...................................................................... 23 Figure 2-11 - Correlation between ocular strain and the daily duration of computer work for the users of single far‐vision lenses, single near‐vision lenses and PALs. Data from Jaschinski et al. (2015). .... 28 Figure 2-12Effect of eye drop use and installation routines on the incidence of dryness during the course of a 4h computer task performed in 20 subjects. Data from Guillon et al . (2004). ................... 31 Figure 2-13 - Schematic representation of contact lens interactions with the tear film. Reproduced from Mann and Tighe, (2013). .......................................................................................................... 32 Figure 2-14 - Changes in equilibrium of water content in daily disposable contact lenses. Data from Pereira and Lira, (2017). .................................................................................................................. 34 Figure 4-1Flowchart of study design and visits. Details of visits and procedure are outlined below. 41 Figure 4-2 - Profile power of contact lenses Biofinity Energy®. (1) and (2) are different samples of the same batch of lenses. ....................................................................................................................... 44 Figure 4-3 - Flowchart of study visits and procedure.** Randomization was performed before lens dispensing visit. Contact Lens assessment was performed at Lens dispensing visit LDV (thirty minutes after lens insertion) and follow-up visit: Day 7 (one week after lens wear *HC: Habitual correction; CLs: contact lenses. ................................................................................................................................. 46 Figure 4-4 - EDTRS chart for HCVA measure (right) and LCVA (left) ................................................. 49 Figure 4-5 - Representation of the video captures process and analysis of the tear film with the topographic and Graph of the variation of the TFS area with time and the NIBUT value presented by the surveyor. .......................................................................................................................................... 51 xvii Figure 4-6 - Hartmann-Shack Aberrometry (Imagine Eyes, IRX-3, Paris) and zernike polynomials (spherical and coma aberration). Modified from google.com/images ................................................. 52 Figure 4-7 - Grand Seiko WAM-5500 open field auto-refractometer (Seiko Co., Ltd., Hiroshima, Japan) with a EDTRS charts (distance and near) used for measurement of accommodative response. ........... 53 Figure 4-8 - View of a central LED with light turned off (A) and (B) turned on at minimum intensity surrounded by other 240 smaller peripheral stimuli. Reproduced from Ferreira-Neves et al. (2015). . 55 Figure 4-9 - Analytical balance used for lens weight measures. ....................................................... 57 Figure 5-1Change in HCVA (A) and LCVA (B) at Baseline with habitual correction (HB) and with each contact lens modality at the 1st day (LDV: lens dispensing visit) and 7th day visit. Error bars represent standard deviation. ........................................................................................................................... 63 Figure 5-2 - Monocular and binocular LDI (A), BFCIrregSD (B) and BFCIrreg (C) at Baseline with habitual correction (HB) and with each contact lens modality at the 1st day (LDV: lens dispensing visit) and 7th day visit. Error bars represent standard deviation. ( ) Statistically significant differences. ...... 65 Figure 5-3 - Changes in Zernike coefficients at Baseline (with HB) and with each contact lens modality at the 1st day (LDV: lens dispensing visit) and 7th day visit. Error bars represent standard deviation. . 67 Figure 5-5 - Changes in Tear film parameters at Baseline and with each contact lens modality at the 1st day (LDV: lens dispensing visit) and 7th day visit. Error bars represent standard deviation. ........... 70 Figure 5-6 – Overtime changes in the frequency, severity and bothersome of vision-related symptoms (QoV questionnaire). Baseline (without lens); 1st day of lens wear (LDV lens dispensing visit); 7th day of lens wear (Day 7). The scale ranges from 1 to 100, with higher scores indicating worse quality of vision. Error bars represent standard deviation............................................................................................. 71 Figure 5-7 - Changes in OSDI scores thourgh time for all contact lens tested. Baseline (without lens); 1st day of lens wear (LDV lens dispensing visit); 7th day of lens wear (Day 7). The scale ranges from 1 to 100, with higher scores indicating more symptoms. Error bars represent standard deviation. ......... 72 Figure 5-8 – Mean of In vitro Dehydration value for Biofinity Energys compared to Bausch + Lomb for two power refraction. Error bars represent standard deviation. ........................................................... 74 xviii Figure 5-9 - Change in water loss over the time for Biofinity Energys (Comfilcon A) and Bausch + Lomb plotted over the three days period. Each data point represents a mean of six measurements. Error bars represent standard deviation............................................................................................. 74 Figure 5-10Mean of Ex vivo Dehydration (%) and Rehydration of each CL tested after one week of lens wear (green bar) and after rehydrating them in saline solution for 24h (yellow bars). .................. 75 Figure 5-11 - Change in water loss (for both eye, all subjcets) over the time for each lens types after seven of wear and after rehydrating them in saline solution for 24h. Each data point represents a mean (of water loss) of seven subjects for each lens. Errors bars represent standard deviation .................... 76 Figure 5-12 - Correlation coefficient (𝑟) between OSDI score and tear film analyses. Note. The abscissa axis represents: a: Biofinity-TFSQ, b: Biofinity Energys-TFSQ, c: Ultra Bausch Lomb-TFSQ, d: Biofinity–TFSQ Area, e: Biofinity Energys–TFSQ Area, f: Ultra Bausch Lomb – TFSQ Area, g: BiofinityBUT, h: Biofinity Energys-BUT, i: Ultra Bausch Lomb-BUT; vertical axis: correlation coefficient. ........... 79 xix LIST OF TABLES Table 4-1 - Justification of of the eligibility criteria included in this study...........................................42 Table 4-2 - Lens parameters used in this study ...............................................................................44 Table 4-3 - Chemical composition of contact lens solution used in this Study ....................................48 Table 4-4Questionnaire response categories and score description (McAlinden et al. 2010) ............56 Table 5-1Characteristics of the patients enrolled in the study..........................................................62 Table 5-2 – Mean ± standard deviation of the accommodative response for the spherical equivalent (M) for each target vergence with the three types of contact lenses fitted ............................................68 Table 5-3 - Correlations (Spearman) between Zernike polynomials and some variables after one week of wear ............................................................................................................................................78 Table 11-1 – Comparison of High and Low Contrast Visual Acuity with the three types of contact lenses fitted. ................................................................................................................................... 114 Table 11-2 – Comparison of Light disturbance with the three types of contact lenses fitted. .......... 115 Table 11-3 – Comparison of aberromtric data with the three types of contact lenses evaluated. .... 116 Table 11-4 - Comparison of tear film analyses with the three types of contact lenses fitted. ........... 117 Table 11-5 – Comparison of QoV with three types of contact lenses fitted. .................................... 118 Table 11-6 - Comparison of OSDI score with three types of contact lenses fitted. ........................... 118 Table 11-7 - Comparison of in vivo dehydration each lens according to power and day of measurements. .............................................................................................................................. 119 Table 11-8 - Comparison of ex vivo dehydration and rehydration for contact lenses studied. .......... 120 xx À minha Mãe! “The size of your dreams must always exceed your current capacity to achieve them. If your dreams don’t scare you, they aren’t big enough.” (Ellen Johnson Sirleaf') “"Development doesn’t happen without transformation, first of people themselves, then of institutions, then of systems." (Graça Machel) Chapter 1: Introduction and Research Rationale Impact of Soft Contact Lenses for Digital Devices on Visual Performance, Tear Film, Accommodative Response and Dehydration in young adult subjects: A Pilot Study 1 Chapter 1 Introduction, Research Rationale and Justification of the study Avelino Nelson F. Mazuze Chapter 1: Introduction and Research Rationale 2 1. INTRODUCTION 1.1 Research rationale and justification of study In the last decade, the use of digital devices has increased significantly and became part of our daily life (Palaiologou, 2014). This exponential growth and expansion of the digital technology and information has led to some consequences and changes in the human eyes (Maducdoc et al., 2017). As a result, the number of people with complaints of vision-related symptoms associated with the use of digital devices such as ocular discomfort, headache, double vision, visual fatigue, irritation, itching, redness, burning, blurred vision, tearing of the eyes and dryness has increased significantly in the consulting room (Talens-Estarelles et al., 2020; Chu, et al., 2011; Parihar et al., 2016; Lin et al., 2019). Several studies have demonstrated that vision and eye-related symptoms are one of the most common complains among digital devices users, and the overexposure to digital displays can cause changes in binocular vision function (accommodation and vergence system) and tear film, not only in the computer workers but also in the general population that use digital devices. (Portello et al., 2013; Reindel et al., 2018; Moon et al., 2016, Chiemeke et al., 2007). Currently, different optical strategies to reduce the symptoms commonly associated to the use of digital devices have been projected and are commercially available in order to improve visual performance, ensure wearer’s comfort and reduce the accommodative demand and binocular vision stress. One of these options that currently are available and have been gained interest by eye care specialist are soft contact lens (CLs) intended for digital devices (Koh et al ., 2019; Sha et al., 2018). Despite the existence of a variety of CLs design and the continuous increasing in CLs fittings, the majority of multifocal contact lenses (MCLs) and single vision contact lenses (SVCL) do not change the accommodative response in healthy young adult subjects (Montés-Mico et al., 2011; Pettersson et al., 2011; Kang and Wildsoet, 2015; Gong et al., 2017; Ruiz-Alcocer et al., 2012; Ruiz-Pomeda et al., 2018; Ruiz-Pomeda et al., 2018). With this in mind, the present dissertation presents a comparative clinical trial of two novel CLs specifically developed for digital devices in young adults subjects. The purpose of this study was to Chapter 1: Introduction and Research Rationale 3 investigate the impact of different designs of soft CLs for digital devices on visual performance, tear film, accommodative response and dehydration in young adult subjects. In this context, this thesis seeks to answer the following research questions: 1. What is the impact of soft CLs for digital devices on visual performance, accommodative response and tear film in healthy young adult subjects? 2. Do soft CLs for digital devices provide a better visual performance and which is their impact on the higher order aberrations in normal young adult subjects? 3. Do soft CLs for digital devices provide greater comfort and better quality of vision in normal young adult subjects? This dissertation begins with an introduction and research rationale (chapter#01). In the chapter#02 a literature review is presented; chapter#03 presents the aims and the hypothesis of the study are outlined; In chapter#04 is described in detail the experimental design and methodology of the study; The chapter#05 presents the results obtained for the main variables relevant in this dissertation. Chapter#06 discusses the results with previous studies. Finally, in the last chapter (charpter#07) the conclusions based on the result of the current research, the limitations of the study and future works are presented. An overview of the Thesis organization followed is shown in Figure 1-1. Chapter 2: Literature Review 10 Figure 2-3 – Visual and ocular symptoms associated with use of digital devices. Reproduced from Coles-Brennan et al. (2019) 2.3 Symptom-inducing risk factors Numerous factors such as lighting, display characteristics, screen reflections, dry eye, high concentration, continuous looking at a fixed object, glare, individual visual problems, poor workplace conditions, improper work habits, refresh rates, radiation and positioning of computer monitors and lesser blinking of eyelids, were describe as potential causes and risk factors for developing CVS (Blehm et al., 2005; Bali et al., 2016; Sheedy and Shaw-McMinn, 2003). Figure 2-4 illustrates the major factors that contribute to symptoms associated with use of digital devices. Chapter 2: Literature Review 11 Figure 2-4 - Factor analysis of visual symptoms related to CVS in 520 office worker. Two dimensions are clearly identified, namely factor 1 (related to dry eye) and factor 2 (associated with ocular accommodation). SBL, sensitivity to bright light; HA, headache; ES, eyestrain; Discomfort, eye discomfort; TE; tired eyes; Burning, burning eyes; DE, dry eyes; BVD, blurred vision looking into the distance; BVvC, blurred vision while viewing the computer; Refocus: slowness in refocusing . Data from Portello et al . (2012). In a review related to computer and visual display terminal (VDT), Parihar et al. (2016) categorized the causes and factor of eye-problem related to the use of digital devices in four groups: (1) environmental and work factors; (2) personal factors; (3) device related factors; (4) ocular surface disorder. The environmental and work factors that mainly contribute to CVS are caused by office air quality, lighting geometry and quality, screen reflections, computer display design such as contrast polarity, resolution flicker and workstation arrangements. Lighting and glare has a significant influence on visual performance when using a computer and digital devices. Research has suggested that the lighting of the workplace must be constant and the room should have the proper types of lighting. Yan et al. (2008) suggest the use of natural or artificial lamps such as filament lamps, fluorescent, incandescent, mercury or sodium. Several studies have revealed the effect of glare and lighting on vision. Wolska and Swituta (1999), for instance, analysed different values of surrounding luminance under 3 lighting conditions and found a significant reduction of the accommodation amplitude Chapter 2: Literature Review 12 (significance level <.05).The authors also observed no statistically significant difference in the value of surrounding luminance on the asthenopic symptoms for either CRT or LCD monitors. Personal factors were also identified as risk factors for vision problems associated with the use of digital devices. The most frequent causes and risk factors include nicotine use, gender, age and refractive error. Refractive error such as hyperopia, myopia and astigmatism are one of the most significant personal factors that can affect visual performance (reduced visual acuity for both distance and near), the comfort and increase the post-task symptoms such as eye strain, headache and blurred vision in computer users (Yan et al., 2008). These symptoms are generally temporary and get worse at the end of the day or after computer use. However, more investigations are needed to study the effect of uncorrected refractive error on task performance associated to computer users. Besides personal factors, other cause of symptoms associated with the use of digital devices is the device-related factors. This cathegory includes the height and angle of video display terminal (VDT), flicker frequency screen resolution, background and text color, and 3D stereoscopic display. Macknik et al. (1991) studied the effects of flicker on space perception using the displacing a flickering target during saccadic eye movements, and observed that at lower flicker rates it was easier to detect the displacements. This finding suggests that higher frequency flickering target on video display terminals may distort space perception easily during saccadic eye movement and increase risk of complain such as eye fatigue in VDT user. 2.3.1 Dry eye and digital devices Dry eye (DE) is recognized as one of the major contributor factor to vision problems associated with the use of digital devices (Ahn et al., 2014; Yaginuma et al., 1990; Tsubota, 1993; Rosenfield, 2011). Reduced lacrimal lipid secretion, decreased of blink frequency, inappropriate workplace humidity, larger palpebral aperture, and incomplete blink were reported as main cause of CVS-related to dry eye (Sheedy and Shaw-McMinn, 2003; Munshi et al. , 2017). Dryness is experienced by up to 21.5% of VDTs users (Uchino et al., 2008). Several studies have investigated the prevalence of dry eye among the computer and digital devices users and the evidence from recent studies suggests that the use of visual display terminal for Chapter 2: Literature Review 13 many hours may cause changes in ocular surface and increase the symptoms (Figure 2-5) commonly associated to CVS. For instance, Portello et al. (2012) investigated the prevalence of visual symptoms in 520 New York City office workers, using The Ocular Surface Disease Index questionnaire (OSDI) and found a high prevalence of dry eye in office workers (32 % and 31% of the subject reported symptoms of dry eye and eye discomfort). The high prevalence of computer-related visual symptoms has been correlated with the OSDI and DED. Likewise, Uchino et al. (2013) investigated prevalence of DED and its risk factors in 672 young and middle-aged Japanese visual VDT users, using dry eye questionnaire (DEQ) and dry eye testing, and found higher prevalence of DED among young to middle-aged Japanese VDT users (the percentage of women with a composite outcome of definite DED or probable DED was higher (76.5%) than men - 60.2%). Decrease in BUT and corneal staining accompanied by normal Schirmer test values were also observed. Equivalent findings were reported by Yokoi et al. (2015) and Moon et al . (2014 ) in a study where the association between VDT use and DED was evaluated in twohundred eighty-eight school Children using a self-administered questionnaire. The authors found an association between the daily duration of smartphone use and increased risk of DED. Furthermore, the authors postulate that the use of smartphone is an important risk factor for developing DED in children. Lastly, Uchino et al . (2008) which have investigated the prevalence of DED in 4393 young and middle-aged Japanese office workers, also observed high prevalence of dry eye in females, CL wearers, and prolonged VDT users. Likewise, Yamanish et al. (2019) compared the prevalence of DED among VDT users using the revised and previous DED criteria and also found an increased prevalence of dry eye from 11.6% to 58.6%, according to the revised DED diagnostic criteria of the Asia Dry Eye Society. Chapter 2: Literature Review 14 Figure 2-5 - Incidence of the ocular symptoms after 4h of computer task in 20 subjects. Data from Guillon et al . (2004). 2.4 Effects of digital devices use on vision 2.4.1 Visual Performance Visual performance is one of the visual parameter that could be affected by a large number of devices and parameters, such as lightning conditions, flicker frequency screen resolution, background and text color, font size, structure, and style and viewing distance (Bali et al., 2019). A few studies have investigated the impact of digital devices on visual performance among the computer users. For example, Ziefle et al. (1998) studied the effect of display resolution on visual performance and observed a strong correlation between visual fatigue and monitor with low-resolution. The authors also concluded that reading performance was significantly better in the paper condition than in the 2 CRT conditions. Lin et al . (2008) studied the influence of different illumination colors (red, blue, green and white) on visual performance and fatigue in VDT workstation and observed that visual acuity was significantly affected by the color of light (Figure 2-6). Chapter 2: Literature Review 15 Figure 2-6 - Change in visual acuity at four lighting colors in 10 subjects. Data from Lin et al. (2008). Lin et al . (2019) investigated the effect of reflected glare and visual field lighting on CVS, measuring different parameters such as visual function tests, questionnaires, and visual performance tests, and found a statistically significant decreased of critical fusion in all groups study after the performance of the visual task. They did not found statistically significant differences in visual function parameters, such as heterophoria, accommodative convergence (AC) per unit of accommodative (A) response (AC/A ratio), and accommodative facility between the first examination and the second examination. In contrast, Safdar et al. (2009) analysed the variation in visual acuity during workday, in forty-eight radiologists, found a statistically significant difference between the visual acuity of radiologists in the morning and visual acuity throughout the day. Besides the glare discomfort, the size of text can also affect the visual performance. Bababekova et al. (2011) analysed the font size and viewing distance of handheld smart phones in 129 subjects with mean age of 23.2 years and concluded that the mean visual acuity required to view comfortably the font size (6/15.1 or 0.8 M letter ) is at least 6/5. Sheedy and Shaw-McMinn (2003) suggested that computer monitor or other form of electronic devices should be three times better than the required to read the text on the display. This would help to minimize the visual symptoms such as tired eyes, blur or eye strain. Chapter 2: Literature Review 16 2.4.2 Accommodation Perform visual activieties at a short distance from the eye for extended periods of time will increase the accommodative demand of the eye system. The same happens when those activities are performed in electronic screens (Coles-Brennan et al ., 2019). Accommodative abnormalities are the major cause of asthenopia, once computer-related activities overload the accommodation mechanism (Amalia et al., 2010). Figure 2-7 illustrates mean values of accommodative response at a viewing distance after 30 mints of computer task. Several studies have investigated the effect of different digital devices on several components of the accommodation system: accuracy of accommodation (accommodation lag), flexibility (accommodative facility) and amplitude of accommodation. However, the results reported are not conclusive. Some studies report an increasing in accommodation (accommodation lag) during near task activities in visual display, while others did not report any change in accommodation (Coles-Brennan et al ., 2019; Bali et al., 2019). For example, Rosenfield et al. (2010) analysed the changes in accommodation system in twenty-two subjects after reading a text from a computer screen during 25 min, and did not found any significant change in monocular accommodative during the computer task. Similarly, in a cross-sectional and observational study where 44 bank employees and 44 people as the control group members were observed, Mahjoob et al. (2013) demonstrated that there was no significant differences in some components of accommodative system such as accommodation range (one eye and both eyes), ease of accommodation (one eye, both eyes), and positive and negative related accommodation in none of the groups. In contrast, a study conducted by Tosha et al. (2009) that aimed to evaluate the magnitude of accommodative errors and variability at different viewing distances in college students with low and high visual discomfort using objective measures of accommodation, found a higher accommodative lag at a near viewing distance over time. The authors also concluded that high visual discomfort was characterized by accommodative fatigue, with a higher lag of accommodation developing at a near viewing distance over time. Likewise, Park et al. (2014) investigated changes in accommodative system in young adult’s subjects, and concluded that the use of smartphones may affect some components of accommodation system such as accommodative amplitude and accommodative facilities (decrease in monocular and binocular, respectively). Chapter 2: Literature Review 17 Alongside with the accuracy of accommodation, many others components of accommodative system were investigated during the computer tasks: micro fluctuations, accommodative facility and amplitude of accommodation. Gray et al . (2000) analysed accommodation micro fluctuations and steady-state accommodation pupil response during the sustained viewing of visual display terminal, in five young visually-normal emmetropic subjects, using a modified Canon Autoref R-1 infra-red objective optometer and a Hamamatsu C3160 Perceptscope Video Area Analyser. The authors did not found a significant variation in the magnitude of the accommodation micro-fluctuations with either display or task duration, nor any significant interaction between these two factors. Harb et al. (2006) studied the behaviour and characteristics of accommodation during the sustained reading in emmmetropes and myopes eyes and found a significant increase in the power of accommodative micro fluctuations with closer demands (p<0.05) and with increasing myopia at closest reading demands (p<0.01). The authors concluded that the difference in the accommodative behaviour between individuals with different refractive states suggests a possible relationship between variability in accommodation and the development of myopia. Simmers et al. (2001) investigated the influence of tinted lenses on ocular accommodation in four different conditions: prescribed tinted lens, neutral density filter, tinted lens of complementary colour and no absorptive lens. The authors found greater low-frequency micro fluctuations in accommodation in the no lens condition than in the other three lens condition. The authors concluded that this may be related to the reduction in luminance in tinted lenses. Saito et al. (1994) examined changes in visual function and accommodative function after a four-hour VDT operation task, and observed that both accommodative facility and amplitude of accommodation decreased significantly after 2h of computer work. In summary, the use of digital devices may affect the accommodative system, by increasing the accommodation lag and decreasing the amplitude of accommodation. However, it is still unclear how exactly computer tasks may affect the accommodative facility. The presence of accommodative insufficiency, accommodative infacility and lag of accommodation associated to refractive asthenopia constitute the most common conditions related to CVS. (Shrestha et al ., 2011). The anomalies of accommodation may be detected by means of the near point of accommodation (NPA). Chapter 2: Literature Review 18 Figure 2-7 - Mean values of accommodative response at a viewing distance after 30 mints of computer task in 20 subjects. Data from Collier and Rosenfield, (2011). 2.4.3 Binocular Vision Vergence system may also be affected by prolonged use of digital devices. Changes in near point of convergence (NPC), near negative fusional vergence and positive fusional vergence associated to exophoria or esophoria at near and distance, after prologued use of digital devices were reported as main signs of anomalies of binocular vision (Rosenfield et al., 2010; Hall and Coles-Brennan, 2015; Watten et al., 1994; Collier and Rosenfield, 2011).The vergence anomaly most commonly related to CVS is convergence insufficiency, which is characterized by poor convergence ability and fusional insufficiency. Few studies have linked the use of digital devices and change in vergence system, but the link between these binocular function and ocular and visual discomfort symptoms related to computer use remains inconclusive (Rosenfield, 2011). Gur et al . (1994) evaluated the effect of 4 days of video display terminal (VDT) in accommodative and vergence system, in 16 visual display units (VDU) and 13 control workers with age between 24 to 43 years, before work at the beginning of the week (first examination) and again four days later at the end of the work day (second examination), using NPA and the near point of convergence (NPC). The authors found a statistically significant decreased in both Chapter 2: Literature Review 19 accommodation and convergence range. Watten et al. (1994) reported significant reduction in NPC positive and negative relative vergence in office workers after eight hours of computer use. The authors concluded that the use of computer may affect the vergence system with decrease of converge and diverge. Gratton et al. (1990) investigated changes in visual function during work with VDT and also found a decrease in fusional convergence and a smaller decrease in divergence in all subjects. The authors concluded that an increase in viewing distance certainly leads to a lower load on accommodation and convergence system during the computer task in office workers. A recent study conducted by Kwon et al . (2016) aimed to investigate the effect of excessive near work activities by using a smartphone on the subjective symptoms, accommodative and convergent function in 40 subjects. The results pointed to a significant decrease of negative fusional vergence. In contrast, Collier and Rosenfield (2011) examined the vergence response using the associated phoria (AP) and observed non significant changes in accommodation or vergence during the course of the 30-minute test period (Figure 2-8). Despite those results, the mean AP for the subjects who reported the greatest discomfort during the task was 1.55D exo and ortho. The authors concluded that a slightly reduced convergence response increases subject comfort during the task, which means that the symptoms related to CVS were significantly worse in subjects who exhibited zero fixation disparity than those who had exo AP. Likewise, a survey study conducted by Phamonvaechavan and Nitiapinyasagul (2017) that aimed to examine the effect of viewing text on computer screen and iPad® on visual symptoms and functions, found a significant change in fusional convergence amplitude at near after sustained reading text in both devices. Chapter 2: Literature Review 26 c) Ambient light should also be adjusted in order to prevent direct light from the back of the monitor and light sources behind the reader. Several studies have demonstrated that improper light is probably the major environmental factor that contributes to visual discomfort in computer users (Yan et al. 2008; Coles-Brennan et al. 2019). Therefore, is recommend that the source of light in a computer room should be half as bright as that normally found in a work place (recommended lighting levels are 40–50 Fc for ambient light). A study carried out by Sheedy et al. (2005) concluded that the screen lighting should be adjusted to the optimum and the luminance of the room should not exceed three times than the mean luminance on the screen. 2.5.2 Management of refractive error Uncorrected refractive errors and presbyopia in computer users or other digital devices users may result in complaints such as blurred vision, slow focusing, headache, double vision or difficulty focusing for close work (presbyopia). Therefore, the correction of refractive errors is important to minimize the symptoms associated with use of digital devices and computers by improving the visual performance and comfort during these tasks (Coles-Brennan et al., 2019). The examination and correction of refractive errors should be performed taking into account the patient's working distance. The final prescription should be done taking into account the current visual demands and the design of lenses, especially in presbyopic subjects. Prescription may include spectacle or contact lenses that have positive refractive power. Wearing bifocal lenses may not be satisfactory because it will require fatiguing head postures due to the position and narrow width of the intermediate and near vision zones. Trifocal lenses that contain three focal points: distance, intermediate and near vision (recommended in case of advanced presbyopic patient who require clear distance vision at computer) and progressive addition lenses (PALs) have been suggested as the optimal correction for presbyopia and hypermetropia, and offer excellent vision correction for people who has high accommodative demand (Sheedy and ShawMcMinn, 2003; Heus et al., 2012). Several studies have been conducted to test the effect of computer glasses (glasses with special design recommended by American Academy of Optometry (AAO ) for patient with CVS) in the relief of symptoms. For instance, Wallin et al. (1994) investigated the effects of computer glasses (term used for AOA to describe the eyeglasses designed to eliminate and/or significantly reduce the visual- Chapter 2: Literature Review 27 ocular problems associated with VDT use) in 79 symptomatic VDT usersand observed that the VDTrelated symptoms were reduced through the use of the computer glasses. Kee et al. (2018) analysed the effects of wearing conventional single-vision lenses (SVL) versus progressive addition lenses (PALs) on the working distance and refractive status, in sixty-four healthy computer users (young and prepresbiopic) and observed that the PALs caused less "increased sensitivity to light" compared with SVL. Specific occupational lenses for computer work have been designed. They have an intermediate vision zone at eye level and specific focal length designed for computer work. It can be more effective and provide better high-quality intermediate and near vision in symptomatic subjects than other eyeglasses such as bifocal lenses and single vision lenses. For example, Hayes et al. (2007) analysed the symptoms and quality of life in computer users and concluded that subjects wearing computer spectacles had lower pain response scores. However, those differences were small and there were no statistically significant differences between them and bifocal wearers in terms of neck, upper back, lower back, and shoulder areas. Jaschinkis et al. (2015) investigated the effects of different types of spectacle lenses (single farvision lenses; single near-vision lenses; and PALs) habitually worn by computer users (Figure 2-11). The authors found a significant correlation between ocular strain, musculoskeletal strain and headache and the daily duration of computer work for the wearers of single far-vision lenses (r= 0.66, n=25; pcor=0.0072) than single near-vision lenses (r= 0.16, n=26; not significant) and PALs (r= 0.13, n=63; not significant). Likewise, in a comparative study of two PALs for general purpose, PALs and computer vision PALs with continuous clear vision between infinity and near, Jaschinkis et al. (2015) found significantly lower head inclination when looking at the monitor in computer vision PALs than with the general purpose PALs. The authors also observed that 44 per cent of the participants preferred the computer vision PALs. Chapter 2: Literature Review 28 Figure 2-11 - Correlation between ocular strain and the daily duration of computer work for the users of single far‐vision lenses, single near‐vision lenses and PALs. Data from Jaschinski et al. (2015). Contact lens prescription should also be considered, however, in cases of severe symptoms associated with dry eye, its prescription should be considered with caution. MCLs and SVC are generally prescribed to young adult patients, and a small amount of plus lens should be considered in presence of symptomatic patients. Several aspects should be consideridend during contact lens prescription, especially in computer workers, which are more prone to develop dry eye and consequently CVS. Along with the patients’ activity, the characteristics of the ocular surface of the patient and the characteristics of the lens (type, design, material, permeability, water content and replacement) should be carefully analysed. Some of the most popular daily disposables for CVS are: Acuvue Oasys, Proclear, Biofinity Energys® (Coopervision) and Bausch + Lomb ULTRA® with claimed especial design for digital devices. Details of designs and caracteritic of theses lenses will be discussed in chapter r 3. Chapter 2: Literature Review 29 2.5.3 Management of binocular vision anomalies Patients with convergence dysfunctions and/or accommodation dysfuntions associated to CVS must be treated with vision therapy or glasses. The prescription of glasses should be indicated in case of blurred vision at all distances. Visual therapy designed for accommodative and vergence anomalies aims to improve the accuracy and dynamics of the accommodation system (accommodative response) and help the patient to achieve better visual performance during the computer task and digital devices and relief ocular symptoms associated with vergence disorders. Visual therapy should be applied in cases where the treatment with the glasses does not improve the symptomatology, and it only has effect when an improvement of both accommodative and vergence systems is achieved. The prescription of low pluspower spectacles (addition power ranging from +0.41 D to +1.25D over the distance prescription) should be effective in case of accommodative disorders in the pre-pesbyopic patient. Patients with poor convergence ability should be treated with vision training with Push-up (high sustained, far-near rock and combination), prism jump, prism reading, lens flippers and flippers reading. In case of vertical phoria problems it is recommended the prescriptions of prism. Plus lenses for near (can be in single vision pair of glasses or a multifocal) should be recommended in case of esophoria. 2.5.4 Management of CVS-Related Dry Eye Treatment followed by patients suffering from CVS-related DED must be multifaceted (Matossian et al., 2019). The treatment should include the use of artificial tears (in case of mild and severity dry eye symptoms), dietary supplement of either omega-3 fatty acids or blueberry extract, changes in ambient humidity, hydration (drinking more water) and frequent breaks - whose benefit is not yet scientifically proven (following the 20-20-20 rule to give your eyes a break: look 20 feet away for 20 seconds, every 20 minutes). All these activities are recommended to moisturise the ocular surface, reduce damage to the corneal epithelium, increase comfort, relax the accommodative system and prevent dryness, irritation, tiredness and difficulty of focusing. Chapter 2: Literature Review 30 Several medicine options have been used to relieve the symptoms of DED and DED related to CVS. For instance, in experimental investigation with an omega 3 fatty acid (O3FA) oral supplement (2,400 mg/day) conducted by Bhargava et al . (2016) in 256 young and middle eyes of VDT users, with ages ranging from 19 to 26 years, they observed significant improvement in symptoms, tear stability, and conjunctival cytology but not tear production in symptomatic VDT users. The authors suggested that the consumption of 2,400 mg/day of O3FA supplement may help to relief the symptoms commonly associated to CVS in symptomatic VDT users. Morita et al. (2018) evaluated the effects of heat-killed Lactobacillus paracasei KW 3110-containing supplements for eight weeks, on improving ocular disorders and symptoms of eye fatigue, in 62 healthy Japanese volunteers of 35 to 45 years of age, who had experienced eye fatigue, and observed a decrease of critical flicker frequency in the Lactobacillus paracasei KW3110 group when compared with the placebo group during the fourth week. The authors suggested that ingestion of Lactobacillus paracasei KW3110 had the potential to relief the symptoms commonly associated to VDT such as eye fatigue, especially high levels of eye fatigue. Others treatment option for relieving the symptoms of CVS-related DED includes: consumption of omega-3 fatty acids (O3FAs); preservative-free eyedrops; and consumption of Vaccinium uliginosum extract (DA9301oral pill (1000 mg/day). For example, Bhargava et al. (2015) investigated the efficacy of dietary consumption of omega-3 fatty acids (O3FAs) on DED symptoms, in 478 symptomatic patients using computers for more than 3 h per day, for minimum 1 year, and demonstrated a significant improvement in computer vision syndrome symptoms related DED, with decreases tear evaporation rate, increase goblet cell density and improved epithelial cellular morphology. Guillon et al . (2004) investigated the effect of povidone 2% preservative-free eyedrops on CL wearers with CVS and found statistically and clinically significant decrease in symptoms of CVS (Figure 2-12). However, the symptoms were not fully eliminated by the use of the test eye drop. Park et al. (2016) investigated the effect of consumption of Vaccinium uliginosum extract (DA9301oral pill (1000 mg/day) during 4 weeks, on tablet computer-induced asthenopia, and observed that oral intake of DA9301 (1000 mg/day for 4 weeks) was effective in the relief of symptoms associated to asthenopia induced by digital devices. Chapter 2: Literature Review 31 Figure 2-12Effect of eye drop use and installation routines on the incidence of dryness during the course of a 4h computer task performed in 20 subjects. Data from Guillon et al . (2004). 2.6 Contact lenses and use of digital devices 2.6.1 Impact of contact lens on ocular surface and use of digital devices The presence of CL on the eye alters the distributions and physiology of the tear film (Figure 2-13), which increases the risk to presenting symptoms commonly associated with DED such as tired eyes, dryness, burning sensation, grittiness and discomfort, due the unstable of tear film and reduced tear film thickness (Coles-Brennan et al., 2019; Kojima, 2018; Kaido et al., 2019). Reddy et al. (2016) investigated the prevalence of DED symptoms among CLs wearers and non-contact lens wearers, and observed that DED symptoms were significantly more prevalent in CL wearers when compared to noncontact lens wearers. Eye dryness (73.5%) was reported as the most frequent symptom in CL wearers while tired eyes (77%) as most frequent symptoms in non-contact lens wearers. There was an increasing trend of their frequency and intensity at the end of the day. Chapter 2: Literature Review 32 Figure 2-13 - Schematic representation of contact lens interactions with the tear film. Reproduced from Mann and Tighe, (2013). CL wear while using VDT at work has been reported to increase the risk to develop CVS related DED, due to the instability of the tear film, associated with increased tear evaporation rate and decreased blink frequency and amplitude. (Tauste et al., 2016; Tauste et al., 2017; Tuaste et al., 2014; Kojima, 2017). Few studies have investigated the impact of CLs on the ocular surface that attempted to link these interactions with the use of VDT and the risk of CVS development. For instance, GonzálezMéijome et al . (2007) evaluated the ocular symptoms among CLs wearers and non CLs wearers in 334 subjects (university population) who use VDT for different periods of time. The group of CL wearers had a higher prevalence of symptoms of red eye, itching and scratchiness, being statistically significant for red eye (p<0.009, χ 2), and scratchiness (p<0.001, χ 2). The authors concluded that soft CL wearers who use VDTs for longer periods of time are more likely to develop symptoms like eye burning and scratchiness than non-CL wearers. Tauste et al. (2016) analysed the effect of contact lens in 426 computer workers, using Computer Vision Syndrome Questionnaire (CVS-Q), and found a higher prevalence of symptoms related to CVS in CL wearers (65%) than non-CL wearers (50%). Kojima et al . (2018) evaluated the impact of CL wear and VDT work on the ocular surface and tear functions through clinical tests and DEQ, and found lower tear meniscus volume, and lower visual and environmental symptom scores between the two groups. The authors concluded that these symptoms increased with duration of computer work, and scores were significantly higher among Chapter 2: Literature Review 33 contact lens wearers. Similarly, Tauste et al. (2017) analysed the effect of CLs of different materials on tear film and ocular surface in 236 office workers, and found higher risk of ocular surface abnormalities in conventional hydrogel wearers, followed by silicone hydrogel wearers when compared to non-wearers. The authors concluded that the CLs wear during VDT at work increased the risk of anterior eye surface changes such as bulbar, limbal and lid redness, and lid roughness, especially in soft contact lens wearers. 2.6.2 Contact lenses and dehydration process One of the most important factors to consider in symptomatic CL wearers is lens dehydration. The dehydration of soft contact - which is a significant cause of CL discontinuation - is related with physical properties of the lens. It is a natural process which consists of water content loss as soon as the lens is placed on the eye Gonzalez-Meijome et al ., 2007). CL dehydration plays an important role on clinical performance of CLs and it is influenced by several factors such as property of the contact lens material, thickness, palpebral aperture, blink rate, tear film quality and environmental conditions (Jones et al., 2013; Pritchard and Fonn, 1995; Tranoudis and Efron, 2004). Little and Bruce (1995) demonstrated that lens dehydration can be influenced by environmental conditions (ambient air flow). The authors concluded that the changes in the CL fitting during wear could be related with lens dehydration. Likewise, Tranoudis and Efron (2004) analyzed the material properties of soft contact lenses made from different materials, and found a statistically significant reduction in water content after increasing the temperature from 20 to 35 ⁰C. The authors further concluded that soft contact lens dehydration leads to a decrease in oxygen transmissibility and total diameter, following a 6 hours open eye wearing period. Currently, numerous techniques are available to measure soft CL dehydration. These include manual or automatic commercial refractometers, gravimetric techniques, thermal analysis technique, thermogravimetric, spectroscopy, nuclear magnetic resonance imaging, and refractometry techniques (Varikooty et al ., 2010). In clinical practice, the gravimetric method - an ex vivo method of estimating lens water content - is more precise than in vitro studies to determinate the water content of hydrogel CL (Gonzalez-Meijome et al., 2006). The automated lens refractometer obtained the water content from the refractive index values. Chapter 2: Literature Review 34 Several studies have analyzed the characteristics of dehydration process of different types of CLs. It was reported that silicone hydrogel lens materials are more resistant to water loss than conventional hydrogel materials (Figure 2-14) (Sindt and longmuir, 2007; Insua Pereira and Lira, 2017; Jones et al ., 2002). Several studied have tried to associate CL dehydration and CL-relared discomfort (including dryness symptoms) in CL wearers (Pereira and Lira, 2017; Dillehay, 2007; González-Méijome et al., 2007). Alhtough some studies concluded that dehydration is one of the major factors contributing to decreased comfort during hydrogel CL wear and that high water content CLs tend to be less comfortable at the end of the day. (Efron et al 1986; Pereira and Lira, 2017), other studies have failed to find an association between lens dehydration and discomfort or dryness (Fonn et al 1999). In summary, although there are controversies in the relationship between dehydration and eye comfort, contact lens dehydration may have an important role on visual quality and overall comfort of the wearers, particularly in contact lenses wearer who complain of dryness at the end of day. Figure 2-14 - Changes in equilibrium of water content in daily disposable contact lenses. Data from Pereira and Lira, (2017). Chapter 3: Hypothesis and Goals of the Study Impact of Soft Contact Lenses for Digital Devices on Visual Performance, Tear Film, Accommodative Response and Dehydration in young adult subjects: A Pilot Study 35 Chapter 3 Hypothesis and Goals of the Study Avelino Nelson F. Mazuze Chapter 4: Material and Methods 42 consequences of the study were full explained. All the research procedures were conformed to the principles of the Declaration of Helsinki. The participants could dropout from the study any time without consequences. All the subjects completed the written informed consent (APPENDIX 1: Consent Form signed by every participant in this thesis project). To assess the eligibility to participate in the study, subjects underwent a full optometric examination, in which the refractive status, visual acuity and ocular health were evaluated. 4.4 Eligibility Criteria Thirteen (13) young adult subjects were recruited from University of Minho for this research. Justification of eligibility criteria is summarised in Table 4-1 and included healthy young subjects with ages between 18 and 30 years, with a best-corrected distance visual acuity (BCVA) of at least 0.00 LogMAR units or better in each eye with the study contact lenses, and with a difference in VA between both eyes less than 0.1 LogMAR units, a spherical refractive error between +3.00 and -3.00D, with astigmatism below 1.00D and less than 1.00D of anysometropia. Subjects must have pupil diameter under mesopic conditions ≥ 6mm on the study. Subjects with severe dry eye, previous refractive surgery, eye infections or irritations, eye diseases or disorders (including history of corneal opacities) that would contraindicate contact lens wear or patients who take ocular or systemic medicines that can affect the visual performance and accommodation response were excluded. Table 4-1 - Justification of of the eligibility criteria included in this study Criteria Gender This criteria exist to ensure that changes in visual acuity (VA) and refractive error (RE) related to the pregnancy could not confound our results. Age Presbyopic subjects were excluded due to eye changes and inaccurate accommodation. These criteria exist to ensure that changes in ocular structures due to aging could not confound our results. Refractive Error These criteria exist to minimize the risk of uncorrected residual astigmatism, which may affect the validity of the results. Ocular Heath Some eye diseases may cause a change in visual performance and accommodation responses or could be contraindicated for wear contact lenses. Visual Acuity This criterion exists to ensure that changes in visual acuity (VA) due to under correction refractive error (RE) could not affect our results. Chapter 4: Material and Methods 43 4.5 Randomization and masking procedure The randomization of the CLs wear was carried out using a computer-generated random (http://www.randomization.com/) (APPENDIX 3). One investigator (Unmasked clinician) conducted the masking process of the CLs and was responsible to perform the CLs fitting and the evaluation of all examinations all the visits: visual acuity, accommodative response, subjective symptoms and aberrations. All the CLs were delivered in the blister in such a way that the subject did not know which lens was being used. 4.6 Study Lenses Three different designs of CLs were bilaterally fitted in random order in thirteen (13) young adult subjects. Each pair of CL was used for 1 week, with a wash-out period of two days between lenses. Biofinity® soft contact lens (Coopervision) was used as control lens to obtain Baseline values with contact lens wear and two different designs of contact lenses for digital devices: Biofinity Energys®, (Coopervision) and Bausch & Lomb ULTRA® soft contact lens were used to meet the objectives of the study. Details of study lenses are described below and Table 4-2 . 1. Biofinity Energys® soft contact lens (comfilcon A, 48% water content) is a monthly disposable soft contact lenses, which presents an optical zone, called “digital optical zone” (Figure 4-2), with multiple aspherical curves in the anterior surface of the optic zone. These multiple aspherical curves distribute the power evenly by simulating a more positive power in the center of the lens that helps to relieve the accommodative effort when subjects change their focus from the screen to a vision in the distance and near. Launched in 2016, this lens is surface treated with an Aquaform technology, which attracts and retains water throughout the lens thus helping the wearer to feel less ocular dryness. This lens has the same parameters as spherical Biofinity® (www.CooperVision.es/BiofinityEnergys): base curve 8.60 mm, central thickness 0.08 mm (for -3.00), diameter of 14 mm and spherical powers of +8 to -12 and Dk/t (160 units for -3.00). 2. Chapter 4: Material and Methods 44 Figure 4-2 - Profile power of contact lenses Biofinity Energy®. (1) and (2) are different samples of the same batch of lenses. Bausch & Lomb ULTRA® is a monthly disposable silicone hydrogel CL (Samfilcon A) with high oxygen permeability 163 Dk/t. This lens is manufactured with MoistureSeal™ technology (MoistureSeal ® technology) which helps the lenses to maintain 95% of their moisture for the entire day (up to 16h of lens wear), reducing ocular syntoms such as dryness and itching. This lens has a water content of 46% and the design is based on geometry of the aspherical front surface to reduce inherent and induced spherical aberration (http://www.bausch.com). 3. The Biofinity® (Comfilcon A) is a monthly disposable silicone hydrogel CL manufactured with Aquaform® Technology. It allows attracting and binding water throughout the lens material to retain moisture even during times of reduced blinking, offering enhanced comfort and vision quality. This lens was designed with an aspheric optical zone to improve vision by minimizing the spherical aberrations of the lens. Table 4-2 - Lens parameters used in this study Brand Biofinity Energys® Biofinity® Ultra Manufacturer Coopervision Coopervision Baush & Lomb USAN Comfilcon A Comfilcon A Samfilcon A H20 content 48.00% 48.00% 46.00% Material SiHy SiHy SiHy Chapter 4: Material and Methods 45 Lens Technology Aquaform technology Aquaform technology MoistureSeal Replacement schedule Monthly Monthly Monthly Oxygen transmissilibilty 160 Dk/t (at -3.00D) 160 Dk/t (at -3.00D) 163 Dk/t (at-3.00D) Center thickness 0.08 @ -3.00D 0.08 @ -3.00D 0.07 @ -3.00D Extended wear Yes Yes Yes Revenue carton size 3 or 6 pack blister 3 or 6 pack blisters 3 or 6 pack blisters Lens Design Aspheric Digital ZoneR Optics lens design Aspheric Aspheric optics Base curve 8.6 mm 8.6 mm 8.50 mm Modulus elasticity 0.75 Mpa 0.75 Mpa 0.70 Mpa Diameter 14.0 mm 14.0 mm 14.20 mm Sphere power +8.00D to -12.00D in 0.25Dsteps (0.50D steps after +/-6.00) +8.00D to -12.00D in 0.25D steps (0.50D steps after +/-6.00D) +6.00D to -12.00D in 0.25D steps (0.50D steps above - 6.00D) Wearing schedule Daily or 6 nights / 7 days Extended Daily or 6 nigths / 7 days Extended Daily or 6 nights / 7 days Extended USAN, United State Adopted Names; Si-Hy, Silicone Hydrogel 4.7 Contact Lenses Fitting Procedure A total of 7 visits were required to complete the study: Baseline visit (Day-0) and 2 visits per CL used (DLV – lens dispensing visit: thirty minutes after lens insertion and follow-up visit: Day 7one week of lens wear). The summary of visits and procedures are shown in Figure 4-3. Firstly, all the participants recruited had to attend to a full enrollment examination (Baseline visit without contact lens wear), which included anamnesis (medical ocular history) and comprehensive optometric eye examinations, such high and low contrast distance and near LogMAR visual acuity, binocular and accommodative function assessment, objective and subjective refraction, slit-lamp examination and fundus examination. Subsequently, the subjects selected were randomly fitted with a pair of either Biofinity®, Biofinity Energys® or Bausch & Lomb ULTRA® soft contact lens for one week each, with a washout period of two days between lenses wear. The fitting process of each contact lens was carried out according to the manufacturer's instructions as available in their fitting guides. One visit was required to carry out the fitting process and prescription of each lens. At each visit, lens fit assessment was performed 20 mins after CL insertion, using slit-lamp biomicroscopy. This assessment determined adequate CL position, movement and Chapter 4: Material and Methods 46 centration (horizontal and vertical). Simultaneously, the high (100%) and low (10%) contrast visual acuity with CL were also evaluated with LogMAR chart (Precision Vision, USA). If the fitting was clinically acceptable, the subjects were programmed to start the study. Subjects were dispensed with the CL and care regimen at the end of the Baseline examination. After the pre-fitting assessment, subjects began a 1-week of wearing each contact lens according to the randomization of the contact lenses, and asked to return one week later for a follow-up visit (Day 7). The same protocol was followed for all the contact lens, and was undertaken under the same testing conditions. The study was completed after 3 weeks of wearing the contact lenses with washout of two days between each lens (one week for each lens). Figure 4-3 - Flowchart of study visits and procedure.** Randomization was performed before lens dispensing visit. Contact Lens assessment was performed at Lens dispensing visit LDV (thirty minutes Chapter 4: Material and Methods 47 after lens insertion) and follow-up visit: Day 7 (one week after lens wear *HC: Habitual correction; CLs: contact lenses. 4.8 Washout period and Lens Care Systems and Solution The participants were scheduled to have two days without contact lens wear (washout period) between different CLs. During this time, subjects were advised not to wear any kind of CL before returning for the next fitting when the second pair of lenses. We think that the design with two days of washout period was adequate to avoid physiological and optical effects resulting from the use of contact lenses and would not compromising our results (Figure 4-3). This wash-out period of 2 days was already mentioned in the literature: A research conducted by Sha et al. (2018), which investigated visual performance of myopia control soft contact lenses in non-presbyopic subjects they recommended a washout period of 48 hours in between 7 days of lens wear; Similarly, Bakaraju et al. (2017), recommend a minimum of 2-night washout period after 1 week of contact lens wear. Likewise, Fernandes et al. (2013), assessing the visual performance with the Biofinity multifocal (MF) and Biofinity single-vision contact lens (SVC), during the 15 days of wearing each lens, also recommended a washout period of 48 hours between each lens type. In other perspective, Pinero et al . (2015), recommended a wash period of 1 week between fittings “to avoid the interference of the potential effect on the cornea and conjunctiva of each contact lens fitting on the next fitting ”, however subjects wore hybrid CL and two silicone hydrogel CL. Additionally, lens care systems, AOSEPT®PLUS with HydraGlyde® Moisture Matrix and Avizor Alvera® Solution, were given to all the participants. Overall, AoSept Plus with HydraGlyde Moisture Matrix ensures a thorough clean and disinfection of any harmful bacteria for any types of contact lens Table 4-3. shows the details of the composition of the lens care systems and solution that was given for all the participants. The subjects were instructed to use the solution following the manufacturer’s instructions. All the patients received appropriate instructions regarding the minimum hours of lens wear per day (6 hours) learning and disinfecting procedures and other important reminders (no overnight wear). All subjects were advised to use all three lenses with the same frequency and hours per day – in order to not skew study result. The principal investigator was also responsible to instruct participants about the handling of CLs before contact lens dispensing. Chapter 4: Material and Methods 48 Table 4-3 - Chemical composition of contact lens solution used in this Study Opti Free® PureMoist ® (Alcon®, Texas, USA) Disinfecting agent Buffer Chelating agent Surfactant Wetting agent Others Polyquaternium - 10.001% MAPD (ALDOX)0.0006% Boricacid; sorbitol Citrate EDTA 0.05% Poloxamine (Tetronic 1304) HydraGlyde (EOBO41; polyoxyethylene poloxybutylen) Aminomethyl propanol (AMP-95) ALDOX, myristamidopropyl dimethylamine; EDTA, ethylenediamine tetra acetic acid; MPDS, multipurpose disinfecting solution; TETRONIC 1304, poloxamine. 4.9 Visits and Assessment Eligible participants who were qualified for the study at the Baseline (Day-0) examination and which were dispensed lenses had to attend 2 visits for each lens: Visit 1: Lens dispensing visit –LDV- (thirty minutes after lens insertion) and follow-up - visit 2: Day 7 (after at least 60 minutes of lens wear). At the beginning of each follow up visit (Day 7), the examiner asked the participants the number of hours of CL wear per day and the compliance information regarding the frequency and duration were registered in spread sheet. Clinical measurements included visual performance, accommodative response, wavefront aberrometry, light disturbance analysis, tear film analysis and two subjective questionnaires. All the experimental procedures performed were non-invasive and the measurements were carried out by an experienced examiner following the standard protocol for each test. Chapter 4: Material and Methods 49 4.10 Clinical Assessments 4.10.1 Visual Performance Monocular and binocular high and low contrast visual acuity (HCDVA and LCDVA, respectively) were assessed with EDTRS vision charts (Precision Vision. IL) in Logmar scale. This chart has shown good reliability in clinical testing and is peformed at 4 m. The EDTRS chart has an equal number of the letters per line with equal spacing between letters and rows, which the size of the letters increases with a logarithmic progression (Ahmed et al . 2018; Dougherty et al. 2005). In the EDTRS chart the line of 20/20 (or 1.0 in decimal scale) is equivalent to 0.00 (zero) in LogMAR scale. The HCDVA and LCDVA, was assessed with the best distance visual correction and with CL in each follow up visits. Figure 4-4 - EDTRS chart for HCVA measure (right) and LCVA (left) 4.10.2 Tear Film Analysis Measurements of tear film stability were performed noninvasively using E300 corneal topography system (E300, Medmont Pty. Ltd., Victoria, Australia). The E300 Medmont corneal topography has software which automatically captures a sequence of images based on specular reflection of a Placido disk on the anterior surface of the cornea or contact lens to analyses the changes Chapter 4: Material and Methods 50 in tear film surface quality and dynamics. The images of the Placido rings provide the Tear Film Surface Quality (TFSQ) (Alonso-Caneiro et al. 2009; Alonso-Caneiro et al. 2009; Kopf et al. 2008; Downie, 2014). For the measurements, the subjects were instructed to fixate on the green light in the centre of the Placido rings, gently blink twice and then keep their eyes open (not wide, but naturally open), while the video recording and measurements of the tear film image were captured by the examiner. Three repeated measurements were taken on each eye with and without CLs. For the analysis of tear film, values of the following metrics were used: The Tear Film Surface Quality (TFSQ) Index: represents the index of surface regularity that is only provided by video keratoscopy. The TFSQ value considered normal is less than 0.1. Whenever this value is greater than 0.1 it will be indicative of dry eye (or at least there was a clear disturbanceof the placid discs). Tear Film Surface Quality Area (TFSQ-Area): represents the area (in percentage) within the 7mm evaluated where the tear film disrupted (area in which tear break-up occurred). The larger the area, the greater the tear film instability. Auto Tear Break-Up Time (Auto-BUT): which represents time (in seconds) at which the TFSQ-Area (%) is calculated to be at least 5.0% in two consecutive photokeratoscopic images (AlonsoCaneiro et al. 2009; Alonso-Caneiro et al. 2009; Kopf et al. 2008;Downie, 2014). Chapter 4: Material and Methods 51 Figure 4-5 - Representation of the video captures process and analysis of the tear film with the topographic and Graph of the variation of the TFS area with time and the NIBUT value presented by the surveyor. 4.10.3 Wavefront Aberrometry Measurements of ocular aberrations were performed using Hartmann-Shack Aberrometry (Imagine Eyes, IRX-3, Paris). For the measurements, the subjects were instructed to fixate on the “E” letter inside the aberrometer (red light spot) and maintaining the eye wide open. All the procedure was done under mesopic conditions to get maximum pupil size without dilatation. The wavefront was quantified using the Zernike system (Figure 3.6) and the aberrations considered were Total of High Order Aberrations (HOA), HOA Root Mean Square (HOA RMS: from from Z3-3 to Z6-6), Spherical-like HOA RMS (including Z40 and Z60) and Coma-like HOA RMS (including Z3-1, Z31, Z5-1 and Z51). Three consecutive measures for each lens (in both eyes) were made and the average of the measurements per eye was taken. Measurements were taken for a 5 mm pupil size. Chapter 4: Material and Methods 58 4.10.10 Dehydration in v itro Measurements of the in vitro dehydration process of CLs were done immediately after open the blister of each lens and after 24 hours and 72 hours after soaking them in the packing solution. To minimize dehydration before obtaining the first reading, the time between taking away the CL from the blister packs and the remove of the excess of moisture was 15 seconds. Two different refractive power [-1.50 diopters (D) and -3.00 diopters (D)] of each one of the CL designs used in the present work (Biofinity Energys ®, Biofinity ® and Baush+Lomb Ultra ®) were measured. Three consecutive measurements of each lens power were made, and the mean of the 6 measurements was calculated. Data value of dehydration rate in vitro were calculated by the following equation based on previous studies (González-Méijome; Lopez-Alemany; Parafita, 2008; González-Méijome; Lopez-Alemany; Almeida; Parafita; Rejofo; 2007). 𝑊𝑎𝑡𝑒𝑟 𝐿𝑜𝑠𝑠 = Weight 1 − Weight 2 Weight 1 X 100 4.10.11 Dehydration ex v ivo Measurements of the ex vivo dehydration process of CLs were performed immediately after CL removal (after one week of lens wear) and 24 h after immersing them in the packing solution. To avoid potential lens contamination during the removal of the lens off the eye, medical gloves were used. The measurements were performed following the same procedure in vitro dehydration. Data value of dehydration in vitro and ex vivo dehydration (dehydration rates) were calculated by the following equation based on previous studies (González-Méijome; Lopez-Alemany; Parafita, 2008; GonzálezMéijome; Lopez-Alemany; Almeida; Parafita; Rejofo; 2007). 4.11 Statistical Analysis Statistical Analysis was conducted using SPSS Statistic software version 23.0 (IBM Inc, IL) and Microsoft Excel version Office 2007. To determine the differences between Baseline (with habitual correction) and CLs modalities in the outcome measured at lens despising visits (LDV) and follow-up Chapter 4: Material and Methods 59 visit (Day 7), a series of Friedman two-way analysis of variance and Post-hoc testing with Bonferroni corrections for multiple comparisons were used to analyse the statistically significant. For pairwise comparisons, Wilcoxon signed-rank test was used to analyse the statistically significant difference between visits for each CL modality. To determine differences between consecutive measures obtained for in vitro dehydration, a series of The Independent sample T-test was used to analyse the statistically significancy, whereas Repeated measures analysis of variance (ANOVA) and Post-hoc testing with Bonferroni corrections for multiple comparisons was used to analyse the statistical significance of differences between lenses in ex-vivo dehydration and rehydration. Furthermore, bivariate correlations were performed using Spearman coefficient correlation to determine the relationships between all variable measured. The correlations were considered strong if they were greater than 0.800, moderately strong if they were between 0.500 and 0.800, reasonable if they were between 0.300 and 0.500 and weak if they were less than 0.300 (Chan, 2003). The level of statistical significance was set at =0.05, and p-values less than 0.05 were considered statistically significant.. Chapter 5: Results Impact of Soft Contact Lenses for Digital Devices on Visual Performance, Tear Film, Accommodative Response and Dehydration in young adult subjects: A Pilot Study 60 Chapter 5 Results Avelino Nelson F. Mazuze Chapter 5: Results 61 5. RESULTS This chapter presents in detail the the results obtained for each variable measured at lens despising visits (LDV) and after seven days of CL wear for each one of the CL tested, as well as the comparative analysis between them. For statistic analysis, data from 1 eye of all 7 subjects who completed the follow-up visits were considered. The results presented in tables and figures were expressed as the mean ± standard deviation (SD) and only one eye (right eye) was considered for the statistical analysis since both eyes were strongly correlated. 5.1 Outcome variable 5.1.1 Main outcome measures Four main outcome variables were investigated in this clinical trial, namely: 1) High and low contrast visual acuity (HCDVA and LCDVA) 2) Accommodative response 3) Tear Film stability 4) Dehydration The four secondary variables investigated in this trial were: 1) Optical quality 2) Light Disturbance Analyzer 3) Quality of Vision of the contact lenses (QoV) 4) Ocular Surface Disease Index Questionnaire (OSDI) Chapter 5: Results 62 5.2 Sample Characteristics Of the total of 13 eligible participants who qualified for the study at the Baseline examination and dispensed lenses, 7 subjects completed all the follow-up visits required. Six (6) subjects were lost to follow-up and did not complete the study protocol due to lack of availability during mobility restrictions related with SARS-Covid-19 pandemic situation. The mean age of the participants was 25.71±3.40 years (range from 22 to 30 years), with 100 % being female. Mean of spherical equivalent (M) was −1.58±0.73 diopters (D) (range from −3.55 to 0.75D). The average of best-corrected visual acuity (BCVA) was - 0.08±0.06 LogMar (range from −0.20 to 0.00 LogMar). Table 5-1 summarizes the demographics and ocular characteristics of all the participants enrolled at Baseline (including dropouts) and the seven subjects that completed the study. Table 5-1Characteristics of the patients enrolled in the study. Parameter Subjects (n=13) Subjects (n=7) Ages (years) Mean ± SD Median (Range) 24.92±3.22 23 (22 to 30) 25.71±3.40 26 (22 to 30) Sex n (%) Male Female 3 (23.1%) 10 (76.9 %) 0 (0%) 7 (100%) M (D) Mean ± SD Median (range) -1.76±1.45 -1.50 (-4.88 to 1.13) -1.58±0.73 -1.50 (-3.55 to 0.75) J0 (D) Mean ± SD Median (range) -0.01±0.20 0 (-0.36 to 0.43) 0.09±0.15 0 (0.00 to 0.43) J45 (D) Mean ± SD Median (range) - 0.04±0.14 -0.00 (-0.25 – 0.32) - 0.04±0.14 -0.00 (-0.25 – 0.22) BCVA (LogMar scale) Mean ± SD Median (range) -0.07±0.06 0 (-0.20 to 0.00) -0.08±0.06 -0.1 (-0.20 to 0.00) M - Spherical equivalent; J0 - Difference in diopter power between the horizontal and vertical meridian; J45 - expresses the value of oblique astigmatism (45º and 135º); BCVA - Best-corrected Visual acuity. Chapter 5: Results 63 5.3 Visual Performance Figure 5-1 shows the changes over time of Monocular High and Low Contrast Visual Acuity in LogMAR scale (HCVA and LCVA) with three types of contact lenses fitted for 7 eyes of the 7 subjetcs that completed the study. There were no differences in the mean HCVA between Baseline (with habitual correction) and follow-up visits with all the lenses tested (all p > 0.05, Friedman test). There was a slight better performance at LDV with the CLs tested for LCVA comparing to Baseline, but without statistically significant differences (all p > 0.05, Friedman test). Comparisons between CLs designs revealed no statistically significant differences between the three lenses in HCVA (all p > 0.05, Friedman test) neither between visits for each lens (all p > 0.05, Wilcoxon). Likewise, there were no statistically significant differences between contact lenses in LCVA (all p > 0.05, Friedman test) neither between visits for each lens (all p > 0.05, Wilcoxon). Figure 5-1Change in HCVA (A) and LCVA (B) at Baseline with habitual correction (HB) and with each contact lens modality at the 1st day (LDV: lens dispensing visit) and 7th day visit. Error bars represent standard deviation. Chapter 5: Results 64 5.4 Light Disturbance Analysis Figure 5-2 shows the changes over time of light disturbance (LD) parameters: Light disturbance Index (LDI), Standard Deviation of the Irregularity of Best Fit Circle (BFCIrregSD) and Best Fit Circle Irregularity (BFCIrreg) for each contact lens modality. There were no statistically significant differences in LD parameters between Baseline (with habitual correction) and follow-up visits with all CLs tested (all p > 0.05, Friedman test) in both monocular and binocular (all p > 0.05, Friedman test). Comparisons between CLs designs in monocular conditions revealed no statistically significant differences in LDI (%) and BFCIrreg (mm)(p > 0.05, Friedman test). There were statistically significant differences in BFCIrregSD only in follow-up visit (Day 7) between Biofinity vs Biofinity Energys and Biofinity vs Bausch + Lomb (p = 0.028, Friedman test and Bonferroni post hoc test), with Biofinity lens showing less irregularity. Relatively to binocular condition, there were no statistically significant differences for any LD parameter between contact lenses modalities (p > 0.05, Friedman test) and between visits for each lenses (all p > 0.05, Wilcoxon). 0 2 4 6 8 10 Baseline Biofinity-LDV Energys-LDV Ultra-LDV Biofinity-DAY 7 Energys-DAY 7 Ultra-DAY 7 LDI (%) Monocular Binocular A Chapter 5: Results 65 Figure 5-2 - Monocular and binocular LDI (A), BFCIrregSD (B) and BFCIrreg (C) at Baseline with habitual correction (HB) and with each contact lens modality at the 1st day (LDV: lens dispensing visit) and 7th day visit. Error bars represent standard deviation. ( ) Statistically significant differences. 0 1 2 3 4 5 Baseline Biofinity-LDV Energys-LDV Ultra-LDV Biofinity-DAY 7 Energys-DAY 7 Ultra-DAY 7 BFC IrregSD (mm) Monocular Binocular B 0 0,5 1 1,5 Baseline Biofinity-LDV Energys-LDV Ultra-LDV Biofinity-DAY 7 Energys-DAY 7 Ultra-DAY 7 BFC Irreg (mm) Monocular Binocular C Chapter 5: Results 66 5.5 Ocular Aberration Figure 5-3 shows the changes over time of Zernike coefficients expressed as oblique astigmatism, defocus, high-order comatic aberrations (3rd order), spherical aberration (4th and 6th order), as well as the root mean square (RMS) up to 8th order of spherical aberration (RMS_SA), secondary astigmatism (RMS_SecAstig) and high order aberrations (RMS_HOA), calculated for a pupil size of 5 mm. There was an increase in Oblique Astigmatism with all CL tested compared to Baseline (all p > 0.05, Friedman test). This increase was more pronounced for Ultra Bausch+Lomb CL. There was a decrease with all CL tested compared to Baseline. This increase was more pronounced for Biofinity Energys and Bausch + Lomb CL. Although there was no significant changes between Baseline and Follow-up Visits in the Horizontal Coma with the Control Lens (Biofinity), there was an augment/ a shift from positive to negative with both lenses tested (Energys and Ultra). The 4th order spherical aberration changed from slighty positive in the Baseline (without lens) to negative in the follow-up visits, being this difference more noticible for the lens tested (Energys and Ultra). There was also an augment (with a shift from positive to negative) in the 6th order spherical aberration from Baseline to Day-7 with the lens tested (Energys and Ultra), but also with the Control Lens (Biofinity). Those augments are decipected in Figure 5-3 F (RMS_SA). Along with the decrease in Defocus with all lenses, there was also a statistically significant decrease in Total RMS with all CLs tested compared to Baseline. Relatively to comparisons between CLs, statistically significant differences were found for coefficients Astig Obli in LDV (Biofinity vs Energys), Horizontal COMA also in LDV (Biofinity vs Ultra; Biofinity vs Energys), SH_4th (Biofinity vs Ultra) and SH_6th in Day 7 (Ultra vs Biofinity; Ultra vs Energys) (all p < 0.03, Friedman test and Bonferroni post hoc test). In contrast, the coefficients Defocus, Vertical Astig, Vertical_COMA, RMS_SA, RMS_COMA, RMS_Astig Sec, RMS_Trefoil , RMS_HOA , RMS_Total did not differ significantly between contact lenses (p > 0.05, Friedman test) and between each lenses modalities (all p > 0.05, Wilcoxon). Chapter 5: Results 67 Figure 5-3 - Changes in Zernike coefficients at Baseline (with HB) and with each contact lens modality at the 1st day (LDV: lens dispensing visit) and 7th day visit. Error bars represent standard deviation. Chapter 5: Results 74 Figure 5-8 – Mean of In vitro Dehydration value for Biofinity Energys compared to Bausch + Lomb for two power refraction. Error bars represent standard deviation. Figure 5-9 - Change in water loss over the time for Biofinity Energys (Comfilcon A) and Bausch + Lomb plotted over the three days period. Each data point represents a mean of six measurements. Error bars represent standard deviation. -16 -14 -12 -10 -8 -6 -4 -2 0 Biofinity Energys Ultra + Bausch Dehydration (%) -1.50 -3.00 Chapter 5: Results 75 5.10.2 Ex vivo dehydration Results of ex vivo dehydration were described in percentages, by means of relative mass lost, which represent the water loss. For each lens modality, an average lens weight of all 7 subjects who completed the study was calculated. Figure 5-10 illustrated the mean of ex-vivo dehydration of Biofinity (Control lens), Biofinity Energys (Comfilcon A) and Bausch + Lomb after one week of lens wear and after 24 hours of rehydration. The representation of profile of ex vivo dehydration curve over the time of each lens modality is ilustretd in Figure 5-11. The mean of ex vivo dehydration rate for Biofinity was - 10.56%±2.40; -13.22%±2.83 for Biofinity Energys; and -13.97% ±2.91 for Bausch + Lomb. There were no statistically significant differences in the ex vivo dehydration rates between CLs after one week of wear (p=0.652, ANOVA). Figure 5-10Mean of Ex vivo Dehydration (%) and Rehydration of each CL tested after one week of lens wear (green bar) and after rehydrating them in saline solution for 24h (yellow bars). -18 -16 -14 -12 -10 -8 -6 -4 -2 0 Biofinity Biofinity Energys Ultra + Bausch Dehydration (%) Ex Vivo Rehydration Chapter 5: Results 76 Figure 5-11 - Change in water loss (for both eye, all subjcets) over the time for each lens types after seven of wear and after rehydrating them in saline solution for 24h. Each data point represents a mean (of water loss) of seven subjects for each lens. Errors bars represent standard deviation Chapter 5: Results 77 5.11 Correlation analysis 5.11.1 Correlation between Zernike polynomials with other variables Table 5-3 presents the results of correlations between Zernike polynomials and HCVA, LCVA, LDI, BFCIrregSD and QoV outcomes (frequency, severity and bothersome of the symptoms) for all contact lenses studied after one week of wear. The subsequent analyses were performed in all contact lenses separately after seven days. There were strong significant and inverse correlations between Defocus and BCFIrreg for Ultra Bausch Lomb (r= -0.964, p < 0. 001), Vertical_Astig and HCVA for Energys (r= -0.791, p <0.05), Vertical_COMA and HCVA for Energys (r= -0.791, p <0.05), Horizontal_COMA and QoV (Severity and Bothersome) for Ultra Bausch Lomb (r= -0.906, p < 0. 001; and r= -0.883, p < 0. 001). A positive strong significant correlation was observed between RMS_Astig Sec and Qov (Freq) with Energys (r= 0.764, p <0.05). For the remaining variables, the Spearman Rho values were not statistically significant ( p >0.05) and vary between weak to strong, for all CLs tested. Chapter 5: Results 78 Table 5-3 - Correlations (Spearman) between Zernike polynomials and some variables after one week of wear HCVA LCVA LDI IrregSD Irreg Freq Sev Both Astig Obli Biofinity -0.611 -0.231 -0.414 -0.532 -0.727 0.514 0.185 -0.018 Energys 0.316 0.107 0.255 -0.505 -0.218 0.079 0.079 0.360 Ultra - 0.538 -0.532 0.607 -0.500 0.255 0.473 0.739 Defocus Biofinity -0.217 0.000 -0.559 -0.126 -0.364 0.110 -0.259 0.091 Energys 0.474 0.060 -0.179 0.491 -0.685 -0.036 0.079 0.198 Ultra - 0.179 0.018 0.321 -0.964† -0.073 0.020 0.054 Vertical Astig Biofinity 0.611 0.347 -0.054 -0.126 0.128 -0.565 -0.148 0.218 Energys -0.791‡ 0.139 -0.107 -0.236 0.613 0.218 0.118 -0.108 Ultra - -0.020 0.162 -0.679 0.179 0.109 0.020 0.054 Vertical_COMA Biofinity -0.315 -0.694 0.559 0.036 0.145 0.128 0.334 0.273 Energys - 0.791‡ -0.558 0.500 0.018 -0.342 -0.327 -0.118 -0.108 Ultra - -0.219 0.000 0.464 -0.107 0.000 0.335 0.613 Horizontal_COMA Biofinity 0.808† 0.579† -0.090 0.685 0.746 -0.606 -0.593 0.200 Energys 0.632 0.020 0.250 -0.109 -0.126 0.109 -0.158 -0.036 Ultra - 0.000 -0.126 -0.500 0.071 -0.665 -0.906† - 0.883† SH_4th Biofinity 0.512 0.463 -0.450 -0.054 0.073 -0.532 -0.148 0.091 Energys -0.632 0.359 -0.071 -0.164 0.234 0.491 0.355 0.378 Ultra - 0.558 -0.450 -0.321 0.357 0.346 0.236 0.432 SH_6th Biofinity 0.059 0.386 -0.847† -0.144 -0.418 -0.257 -0.408 -0.327 Energys -0.399 0.000 0.126 -0.505 0.536 0.156 -0.030 -0.127 Ultra - -0.080 0.300 -0.126 -0.306 0.193 0.268 0.355 RMS_SA Biofinity 0.315 0.347 0.198 0.054 0.182 -0.110 -0.111 -0.218 Energys 0.474 -0.339 0.036 0.055 0.360 -0.436 -0.591 -0.739 Ultra - -0.418 0.577 0.143 0.000 -0.073 -0.236 -0.595 RMS_COMA Biofinity -0.099 -0.347 0.396 -0.342 -0.037 -0.037 0.408 0.055 Energys 0.316 -0.219 0.393 -0.327 0.072 -0.727 -0.394 -0.252 Ultra - -0.239 0.036 0.321 -0.107 0.182 0.571 0.703 RMS_Astig Sec Biofinity 0.315 0.0579 -0.198 -0.144 -0.127 -0.184 -0.259 -0.491 Energys 0.000 -0.020 0.179 0.546 -0.306 0.764‡ 0.709 0.685 Ultra - 0.100 0.378 -0.250 -0.179 0.346 0.059 0.703 RMS_Trefoil Biofinity -0.375 -0.617 0.378 0.198 0.127 0.073 0.0482 -0.055 Energys 0.632 -0.299 0.750 -0.491 -0.162 -0.382 -0.158 0.054 Ultra - -0.100 -0.450 -0.143 0.607 -0.255 -0.020 0.360 RMS_HOA Biofinity 0.177 0.039 0.000 -0.054 0.036 -0.441 0.259 -0.346 Energys 0.632 -0.418 0.714 -0.400 -0.036 -0.491 -0.256 -0.126 Ultra - -0.485 0.360 0.321 -0.179 0.182 0.532 0.541 RMS_Total Biofinity 0.374 0.733 -0.901† -0.378 -0.418 -0.330 -0.445 -0.145 Energys 0.316 0.418 0.107 0.218 -0.288 0.109 0.079 0.396 Ultra - 0.657 -0.180 0.143 -0.321 0.600 0.493 0.577 † P <0.001 ‡ P <0.05 Chapter 5: Results 79 5.11.2 Correlation between OSDI and tear film parameters Figure 5-12 shows the correlation between OSDI and tear film parameters after one week of lens wear. Although without statistical significance (all p>0.05), there were strong correlationns between OSDI Score and TFSQ and TFSQ Area for Biofinity Energys (r=0.714; r=0.786) and between OSDI Score and TFSQ for Ultra CL(r=0.714), whereas moderated but inverse correlations for Biofinity between OSDI Score and TFSQ and TFSQ Area (r=-0.631; r=-0.667). Figure 5-12 - Correlation coefficient (𝑟) between OSDI score and tear film analyses. Note. The abscissa axis represents: a: Biofinity-TFSQ, b: Biofinity Energys-TFSQ, c: Ultra Bausch Lomb-TFSQ, d: Biofinity–TFSQ Area, e: Biofinity Energys–TFSQ Area, f: Ultra Bausch Lomb – TFSQ Area, g: BiofinityBUT, h: Biofinity Energys-BUT, i: Ultra Bausch Lomb-BUT; vertical axis: correlation coefficient. -0,631 0,714 0,736 -0,667 0,786 0,286 0,4 -0,63 0,519 -1 -0,8 -0,6 -0,4 -0,2 0 0,2 0,4 0,6 0,8 1 a b c d e f g h i Correlation conficient (r) Tear Film Parameters Correlation conficient (r) Chapter 6: Discussion Impact of Soft Contact Lenses for Digital Devices on Visual Performance, Tear Film, Accommodative Response and Dehydration in young adult subjects: A Pilot Study 80 Chapter 6 Discussion Avelino Nelson F. Mazuze Chapter 6: Discussion 81 6. DISCUSSION In this chapter, the results obtained will be discussed. Following the structure of the presentation of the results and the relationship between some variables, in the next pages, the results of the present study will be discussed and compared with the results of other studies that evaluated the same lens materials or other, or which used the same devices that were used in the present research. The potential effects of the use of digital devices in CL wearers and non-CLs wearers on the visual performance, accomodative response and ocular surface are well documented. However, few clinical trials have investigated the effect of novel soft CLs specially designed for those young adults who spent many hours working with digital devices (Yuan et al. 2020; Talens-Estarelles et al. 2020; TalensEstarelles et al. 2021; Tuaste et al. 2016). In the present study, we compared the effect of two novel CLs modalities specially designed with new tehcnologies for maintaining moisture or optical properties to minimize the effects of the use of digital device on visual performance, optical quality, accommodative response, tear film stability during the computers tasks: Biofinity Energys ™ lenses, a lens with the same mechanical characteristics as Biofinity ®, but designed with a new optic zone called Digital Zone Optics ™, which promise to reduce eye strain caused by the need to focus close up when using digital devices. Bausch + Lomb ULTRA® with highest oxygen transmissibility (Dk/t 163) and lowest modulus (70 g/mm2), offering moisture retention for a full 16 hours, better end of day vision for digital device users and a new technology (MoistureSeal ® technology) which helps the lenses prevent dehydration blur and maintain 95% of their moisture for the entire day (up to 16h of lens wear), reducing ocular syntoms such as dryness and itching. In terms of visual performance, there was improvement in HCVA and LCVA with both CLs for digital devices (Bausch + Lomb and Biofinity Energys) without significant differences between designs. Notably, in present study, there was a trend of the Bausch + Lomb CL to provide better distance HCVA and worse LCVA comparatively to Control lens (Biofinity) and Biofinity Energys after one week of wear, while the Biofinity Energys remained stable over the follow-up period. Fedtke et al. (2016) evaluated the visual performance of single vision and multifocal contact lenses in non-presbyopic myopic eyes. Similar to our results, they found an average of HCVA of −0.06 to −0.10 logMAR for different lenses. Sha et al. (2020) evaluated the visual performance of soft contact for myopia control in non-presbyopic: MiSight™, Chapter 6: Discussion 82 center-distance Proclear® Multifocal (+2.00 D add), and two prototype lenses. Similar to our results, they found an avarege of HCVA and LCVA of -0.01±0.08 and 0.18±0.12, respectively. Concerning the aberrometry outcomes - analyzed for a 5-mm pupil size –, the present study found some significant changes in some aberration terms with CLs tested, as seen in Figure 5-3. Those changes were found in the coefficients: Astig Oblique, Horizontal COMA, 4th and 6th order spherical aberration. The Total HOA decreased with CLs tested compare to baseline, while the HOA RMS Total remained the same with CLs tested compare to baseline over seven days, but without statistically significant differences. Despite the increase observed in some coefficient such as 4th and 6th order spherical aberration (the higher order aberration with largest influence on visual acuity) there were no statistically significant correlations between them and HCVA or LCVA. Wagner et al. (2015) studied the profile power of single vision and multifocal soft contact lenses. Regarding single vision contact lenses, the authors observed a greater presence of negative spherical aberration in most of single vision evaluated, which is in accordance with our results. McAlinden et al. (2010) evaluated the effect of aspheric designs of two contact lenses: Balafilcon A (PureVision) and Comfilcon A (Biofinity). Differently to our results, the authors found no changes in spherical aberration, but changes in other HOA. Likewise, Roberts et al. (2006) quantified the aberrations induced by soft CLs in normal eyes with myopia. Differently to our results, the authors found increased levels of total HOA. However, despite there were no statistically significant differences between measurements with and without CLs, there was an increase in total coma, trefoil and spherical aberrations. The sign of spherical aberration induced by different CLs designs can be important, particularly under low light conditions (Santolaria Sanz et al., 2015). Our light disturbance results showed a significant increase (deterioration in the sensation) only for BFCIrregSD with CLs for digital devices compared to control, while size (LDI) and irregularity (BFCIrreg) underwent a decrease with CL tested, but without statistical difference, as showed in Figure 5-2. Martins et al. (2020) evalueted light disturbance of different contact lens prototypes with potential for myopia control using as control lens (Biofinity) and the same testing device used in the present study. The authors found a significant increase in size of disturbance (LDI) with the lenses tested compared to the control lens. In this same study, the mean values of in LD parameters for Control lens (Biofinity) was sligh lower than the values reported in the present study - the mean LDI value was 4.65±2.25, 0.42±0.35 for irregularity (BFCIrregSD) and irregularity (BFCIrregSD) 2.83±1.57and similar with Test lenses. Fernandes et al. Chapter 6: Discussion 83 (2018) assessed the light disturbance on two different presbyopic contact lens corrections: multifocal contact lens (Biofinity Multifocal) and monovision (Biofinity Monofocal) using the same testing device. The authors found a significant increase in LDI and BFCRadius parameters for monovision (Biofinity Monofocal), comparatively to baseline. Considering the power profile and lens material of the CLs studied some statistically significant differences between contact lenses modalities in the LD outcomes were expected in the current study. García-Marqués et al . (2021) compared the light disturbance for myopia control contact lens and a single vision contact lens (Biofinity, Comfilcon A, USA) using the same testing device. They found higher light disturbance with multifocal contact lenses design than single vision contact lens. The authors concluded that the design of contact lens (dual-focus) may have affected the light disturbance. Since Biofinity Energys has a different design (Digital Zone Optics TM) to help near vision activities, it should be expected that this lens design could somewhat deteriorate the quality of vision under dim light conditions. However, although without statistically significant differences, the Bausch + Lomb CL showed a worse monocular performance for both size and irregularity of light disturbance (LDI and BFCIrregSD), when compared to both Biofinity (Control lens) and Biofinity Energys. Because of that, differences between lenses could be explained with the sign of spherical aberration. The impact of CLs for digital devices in night visual disturbances could be more explored in future stuideis, due to the effect of the illumination of the digital devices on near task. The impact of soft CLs on night vision disturbances is also an important factor to analyze the clinical performance of soft CLs for digital devices. The subjective sensation of vision-related phenomena improved - both frequency, severity and bothersome - for Biofinity (Control lens) and Biofinity Energys contact lenses, while Bausch + Lomb underwent a increased when we compared to Baseline over a short-term, but without statistical significance (Figure 5-6). Several studies have assessed the Qov with different designs of CLs. Fernandes et al. (2018) evaluated the QoV for multifocal CL for presbyopia correctionand compared it with a monofocal CL (Biofinity Monofocal). Similarly to our study, they did not find significant changes in quality of vision questionnaire between CLs. Recently, Garcia - Marques et al. (2021) compared the optical and visual performance of a dualfocus contact lens used for myopia control with a single-vision contact lens of the same material and found a statistically significant difference between contact lens designs in QoV. 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APPENDIX 1: Consent Form signed by every participant in this thesis project DOCUMENTO DE CONSENTIMENTO INFORMADO No âmbito da Tese de Mestrado em Optometria Avançada, na Universidade do Minho, com o tema “Visual Performance, Accommodative Response and Dehydration of Soft Contact Lenses for Computer Vision Syndrome and Digital Eyestrain in young adult subjects", a decorrer no Laboratório de Investigação de Optometria Clínica e Experimental (CEORLab) da Universidade do Minho, o presente documento tem como objetivo informá-lo sobre o procedimento, exames que serão realizados, riscos e benefícios inerentes ao estudo para o qual irá participar, bem como sobre os obter o seu consentimento para a realização do estudo em causa. O presente documento e os procedimentos a que dizem respeito enquadram-se na “Declaração de Helsínquia” da Associação Médica Mundial (Helsínquia 1964; Tóquio 1975; Veneza 1983; Hong Kong 1989; Somerset West 1996 e Edimburgo 2000, Seul 2008). Hoje em dia, muitas pessoas passam horas e horas todos os dias na frente da tela do computador, telemóveis e tabletes. O esforço que os nossos olhos fazem ao se concentrarem por muito tempo na frente da tela e o tipo de luz que estes dispositivos emitem pode afetar a saúde dos olhos. Os tipos de efeitos decorrentes do uso prolongado incluem redução da taxa de pestanejo, secura, irritação, vermelhidão, fadiga ocular e visão desfocada, entre outros. Para pessoas que usam lentes de contato, esse efeito pode ser ainda mais significativo. Para minimizar esses efeitos, existem atualmente lentes de contato com propriedades mecânicas e ópticas que pretendem proporcionar o alívio dos sintomas associados ao uso destes dispositivos. A presente investigação tem o objetivo de avaliar a eficácia destas lentes de contacto no alívio dos sintomas associados com a Síndrome Visual de Computadores. Portanto, pretende-se avaliar a Voluntário _____ 2020 APPENDIX 111 performance visual, resposta acomodativa, desidratação e a qualidade ótica de duas novas lentes de contacto (Biofinity Energys; Ultra Baush Lomb e Biofinity Monofocal – como lente de controlo) para Síndrome Visual do Computador em sujeitos jovens adultos expostos a esforço visual intenso nas condições descritas. O estudo terá duração de aproximadamente 3 semanas e o procedimento experimental será realizado no Laboratório de Investigação em Optometria Clínica e Experimental (CEORLab), do Centro de Física da Universidade do Minho e, consistirá na avaliação da acuidade visual, acomodação, estabilidade lacrimal medida com um topógrafo corneal e desidratação com 3 lentes de contacto de diferentes desenhos em ambos os olhos. Cada procedimento terá uma duração no máximo de 20 minutos e será feito nos dois olhos (monocular e binocular). Para tal usar-se-ão os seguintes instrumentos: - Acuidade Visual: é um exame não invasivo que expressa a capacidade de descriminar formas (pequenos detalhes), ou seja, letras com alto e baixo contraste. É um teste monocular, onde o paciente fica sentado, com o olho esquerdo tapado e pede-se para que olhe para a tabela e leia as letras até onde consegue ver. Serão realizadas medidas com escalas de alto e baixo contrastee contraste inverso. As medidas serão feitas a cada olho separadamente e a ambos os olhos simultaneamente (condições binoculares) - Aberrometria: é um exame monocular, não invasivo em que o paciente permanece sentado fixando um alvo de luz de cor vermelha (letra E) que mede as aberrações óticas do olho, a partir de um feixe de laser infravermelho, focado na retina. O exame tem uma duração de 5 mints e serão feitas duas medidas para cada olho. - Distorção luminosa: medida do espalhamento de uma fonte de luz brilhante contra um fundo escuro realizado a cada um dos olhos, e ambos os olhos (binocularmente). - Topografia: medida da curvatura da superfície anterior da lente de contacto durante 30 segundos pra avaliar a estabilidade do filme lacrimal disposto à frente da lente. - Auto refratómetro: é uma técnica não invasiva que permite determinar a resposta acomadativa quando se afasta ou se aproxima um objeto do paciente em condições monoculares e binoculares. As medidas serão realizadas em ambos os olhos (direito e esquerdo). Após o registo dos valores iniciais com a correção habitual do paciente, serão realizadas novamente medições após duas APPENDIX 112 situações distintas na seguinte ordem: Paciente com lentes de +2,50D durante 3 minutos, a utilizar o seu telemóvel a uma distância de trabalho de 20cm; Paciente com lentes de -2,50D Cada voluntário utilizará as 3 lentes descritas no estudo em ordem aleatória, durante uma semana. Por questões metodológicas não sendo informado de qual será a lente a usar em cada momento pelo que se por algum motivo for preciso identificar a lente, deverá contatar a equipa de investigação. As medidas supramencionadas serão obtidas antes de iniciar a participação no estudo para caraterizar o estado refrativo e de saúde ocular de cada voluntário, e no final de um período de 5 a 7 dias tendo usado a lente. Reações adversas As reações adversas resultantes do uso de lentes de contacto para Síndrome Visual de Computador serão as mesmas do uso de lentes normais, e incluem: ardor, prurido e/ ou sensação de picada nos olhos, desconforto, sensação de corpo estranho nos olhos, vermelhidão do olho, aumento do lacrimejar, secreções oculares anormais, deficiência visual, visão turva halos à volta dos objetos, sensibilidade à luz (fotofobia) e secura ocular. Em casos pouco raros poderá acontecer inflamação ou infeção da superfície do olho o que poderá provocar supuração ocular, dor, sensação de corpo estranho no olho, fotofobia, perda da visão entre outras. Em casos de verificar um dos sinais acima descritos durante o estudo é importante que informe o investigador. Condições de confidencialidade e financeiras Antes e durante todo o processo do referido estudo, o participante poderá entrar em contacto com os investigadores a fim de obter qualquer esclarecimento que possa advir. Os resultados da investigação poderão ser tratados estatisticamente e publicados com propósitos pedagógicos e científicos, mantendo sempre o anonimato do voluntário. Não há quaisquer custos envolvidos para o voluntário pela participação neste estudo, nem pagamentos ou gratificações que lhe sejam devidas pela mesma participação. APPENDIX 113 A participação no estudo é voluntária podendo desistir a qualquer momento, sem que essa decisão tenha qualquer tipo de consequência. Coloque as iniciais do seu 1º e último nome à frente de cada afirmação se concordar com a mesma: Li e compreendi este documento; Foi-me prestada a informação necessária, e foi igualmente dada oportunidade de colocar qualquer questão, tendo sida respondida de modo satisfatório; Concordo em que seja realizado o procedimento, que consiste na colocação de 3 tipos de lentes de contacto para Síndrome Visual de Computador, com desenhos distintos, e a posterior execução dos exames descritos anteriormente; Compreendo que posso recusar, a qualquer momento, participar neste estudo sem qualquer tipo de consequências; Concordo em que os dados obtidos sejam utilizados de forma anónima para fins científicos e/ou académicos que a equipa investigadora considerar apropriados. Braga, _______ de _______________________ de 2020 Assinatura do participante_______________________________ Assinatura do investigador______________________________ Atenciosamente Investigador: Avelino Nelson Filipe Mazuze Email: [email protected] Contacto do Investigador Principal: Profa . Rute Juliana Ferreira Macedo de Araújo Email: [email protected] Contacto do Investigador Principal: Prof. José M. González Méijome Email: [email protected] APPENDIX 114 11. APPENDIX 2 - Tables of values described throughout the dissertation project. Table 11-1 – Comparison of High and Low Contrast Visual Acuity with the three types of contact lenses fitted. Measurement Contact Lens LDV Day 7 p-valeu1 HCVA Monocular Biofinity -0.10±0.04 -0.09± 0.06 p=0.285* Biofinity Energys -0.08±0.03 -0.07±0.04 p=0.317* Ultra Bausch Lomb -0.10±0.04 -0.10±0.00 p=0.655* p-valeu2 p=0.779 † p=0.549 † LCVA Monocular Biofinity 0.04±0.05 0.07±0.07 p= 0.157 * Biofinity Energys 0.04±0.05 0.08±0.06 p= 0.083 * Ultra Bausch Lomb 0.05±0.05 0.08±0,06 p= 0.157 * p-value2 p=0.717 † p=0.819 † LDV – lens dispensing visit after more than 15 minutes of lens wear; p-valeu1 – differences between visits for each lens; p-valeu2 – Differences between lenses for each visit; (†)Friedman test and Bonferroni post hoc test.; (*) Wilcoxon; statistically significant differences between contact lenses modalities highlighted in bold. APPENDIX 115 Table 11-2 – Comparison of Light disturbance with the three types of contact lenses fitted. Parameter Contact Lens LDV 7 days p-value1 LDI Mon (%) Biofinity 5.18±2.24 6.49±2.76 p=0.416* Biofinity Energys 6.20±3.25 5.69±1.23 p=0.735* Ultra Bausch Lomb 8.17±2.89 5.60±1.40 p=0.063* p-valeu2 p=0.341 † p=0.964 † LDI Bin (%) Biofinity 4.40±1.09 4.06±1.75 p=0.138* Biofinity Energys 4.34±1.68 3.91±0.30 p=0.599* Ultra Bausch Lomb 3.89±0.72 4.96±1.61 p=0.068* pvalue2 p= 0.504 † p=0.084 † BCF IrregSD Mon (mm) Biofinity 2.16±2.05 2.34±1.65 p=0.917* Biofinity Energys 2.21±1.65 3.45±1.05 p= 0.128* Ultra Bausch Lomb 3.57±0.74 3.45±1.05 p= 0.866* p-value2 p= 0.135 † p=0.028 † Post hoc test x Biofinity vs Ultra Biofinity vs Energys BCF IrregSD Bin (mm) Biofinity 1.73±1.64 1.89±1.86 p=0.500* Biofinity Energys 1.93±1.80 1.05±1.34 p=0.293* Ultra Bausch Lomb 1.57±1.55 1.83±1.73 p=0.465* p-value2 p= 0.623 † p=0.554 † BCF Irreg Mon (mm) Biofinity 0.22±0.30 0.36±0.32 p=0.345* Biofinity Energys 0.37±0.27 0.43±0.34 p= 0.499* Ultra Bausch Lomb 0.39±0.21 0.37±0.29 p= 0.799* p-value (DBLFV) p= 0.341 † p=0.772 † BCF Irreg Bin (mm) Biofinity 0.16±0.22 0.16±0.20 p=1.00* Biofinity Energys 0.17±0.20 0.17±0.22 p=0.917* Ultra Bausch Lomb 0.17±0.17 0.11±0.17 p=0.461* p-value2 p= 0.854 † p=1.93 † Mon – Monocular; Bin - binocular; LDV – lens dispensing visit after more than 15 minutes of lens wear; p-valeu1 – differences between visits for each lens; p-valeu2 ; (†) Friedman test and Bonferroni post hoc test.; (*) Wilcoxon; Statistically significant differences between contact lenses modalities highlighted in bold. X—non-statistically significant differences with a pair-by-pair comparison. APPENDIX 122 o ENERGYS 9. o ENERGYS o CONTROL o ULTRA 10. o ENERGYS o ULTRA o CONTROL 11. o ULTRA o CONTROL o ENERGYS 12. o ULTRA o ENERGYS o CONTROL 13. o CONTROL o ULTRA o ENERGYS 14. o ENERGYS o CONTROL o ULTRA 15. o ULTRA o CONTROL o ENERGYS 16. o CONTROL o ULTRA o ENERGYS 17. o CONTROL o ULTRA APPENDIX 123 o ENERGYS 18. o ULTRA o ENERGYS o CONTROL 19. o ENERGYS o CONTROL o ULTRA 20. o CONTROL o ULTRA o ENERGYS 21. o ENERGYS o ULTRA o CONTROL 22. o ENERGYS o ULTRA o CONTROL 23. o ENERGYS o ULTRA o CONTROL 24. o ULTRA o ENERGYS o CONTROL 25. o CONTROL o ULTRA o ENERGYS 26. o ENERGYS o CONTROL APPENDIX 124 o ULTRA 27. o ULTRA o ENERGYS o CONTROL 28. o ENERGYS o ULTRA o CONTROL 29. o CONTROL o ENERGYS o ULTRA 30. o CONTROL o ENERGYS o ULTRA