The changes and causes of asthenopia after ICL implantation.

OBJECTIVE: To detect the presence of asthenopia after implantation of Implantable Collamer Lens (ICL). METHOD: Design: prospective observational case series. Patients with myopia and/or astigmatism who underwent ICL surgeries and completed 3-month follow-up were enrolled. Asthenopia scores, amplitude of accommodation (AA), positive/negative relative accommodation (PRA/NRA), accommodative facility (AF), the ratio of accommodative convergence and accommodation (AC/A), Schirmer test, noninvasive breakup time (NBUT), and HOA were examined before surgeries and at 1 week, 1 month and 3 months postoperatively then statistically analyzed. RESULTS: Symptoms of asthenopia were significantly decreased at 1 week after ICL surgeries than those before surgeries, but increased gradually as time went by, eventually recovered at 3 months postoperatively. AA, AF, AC/A decreased 1 week postoperatively, returned to the baseline at 1 month and were improved at 3 months after surgeries. NBUT at 1 week, 1 month and 3 months after surgeries were significantly decreased and was the lowest at 1 week postoperatively. PRA, NRA, Schiermer values and HOA had no significant change. Correlation analysis showed that the lower AF and NBUT after ICL surgeries, the more severe the asthenopia symptoms. CONCLUSION: The symptoms of asthenopia aggravated transiently after ICL implantation surgeries, but improved gradually with time. AF and NBUT were important factors affecting the changes of asthenopia.

The effect of blue light filter on visual and task performance.

PURPOSE: This study aimed to determine the effect of the blue light (BL) filter on the different tasks performed on a laptop on a daily basis. METHODS: Forty subjects were required to perform a 45-minute task on the laptop screen with or without the BL filter on two different days. In the first task, subjects were made to watch a video. In the second task, subjects were made to read a passage from the laptop for 3 minutes, and reading speed was calculated. In the third task, subjects were made to enter the data on the laptop. The time taken to fill in the data was recorded. After the completion of the task, questionnaires were administered. Pre- and post-task accommodative tests were performed. RESULTS: Forty emmetropes with a mean age of 21 ± 2 were recruited. In visual performance, the subjective response showed a significant difference in visual fatigue level with and without the filter. A statistically significant difference was seen in reading speed and data entry during task performance with and without the filter. Pre- and post-task accommodative parameters showed variable responses. CONCLUSION: This study showed that the use of a BL filter improves task performance, but subjectively, people experienced more visual fatigue while using the filter.

Refractive error changes and associated asthenopia observed after COVID-19 infection: Case reports from two continents.

COVID-19 infection has been linked to various ocular complications and complaints, but not to refractive errors. In this case report, we present ethnically diverse patients who reported asthenopic symptoms shortly after recovering from COVID-19 infection. The hyperopic shift in the refractive error, post-COVID could indicate the ciliary body muscle's inability to sustain accommodation, resulting in asthenopia. Hence, refractive errors should also be considered as a post-COVID complication, even if the magnitude is small, especially when patients have a headache and other asthenopic symptoms. Performing dynamic retinoscopy and cycloplegic refraction will also aid in the better management of these patients.

The 20/20/20 rule: Practicing pattern and associations with asthenopic symptoms.

Purpose: The present work style and lifestyle have increased the digital device use. Therefore, an increase in digital eyestrain is to be expected. We undertook a survey during coronavirus disease 2019 (COVID-19) pandemic to investigate the practice of 20/20/20 rule and its association with digital device use and asthenopic symptoms. While this rule is commonly advised, little is known about its validity. Methods: An online survey form was disseminated through social media and emails. The questions for eye-related symptoms were similar to the convergence insufficiency symptom survey (CISS). Participants with age ≥5 years were included, with parents completing the survey for children (≤16 years). Results: A total of 432 participants (mean ± standard deviation [SD]: 26.06 ± 13.92 years) were enrolled, of which 125 responses were for children. The 20/20/20 rule was practiced only by 34% of the participants either regularly (n = 38) or occasionally (n = 109). Those who had complaints of burning sensation and headache tended to practice this rule. Among adult participants, more females (47%) practiced this rule when compared to males (23%). Also, adult females significantly (P = 0.04) had more symptoms score when compared to males. In children, no such gender difference was found. Conclusion: Only one-third of participants practice the 20/20/20 rule at least occasionally. More number of adult females being symptomatic and practicing in greater number could be due to higher prevalence of dry eye condition in females. While the symptom of burning sensation could be related to dry eye, that of headache could be related to refractive error or binocular vision dysfunctions.

TFOS Lifestyle: Impact of the digital environment on the ocular surface.

Eye strain when performing tasks reliant on a digital environment can cause discomfort, affecting productivity and quality of life. Digital eye strain (the preferred terminology) was defined as "the development or exacerbation of recurrent ocular symptoms and/or signs related specifically to digital device screen viewing". Digital eye strain prevalence of up to 97% has been reported, due to no previously agreed definition/diagnostic criteria and limitations of current questionnaires which fail to differentiate such symptoms from those arising from non-digital tasks. Objective signs such as blink rate or critical flicker frequency changes are not 'diagnostic' of digital eye strain nor validated as sensitive. The mechanisms attributed to ocular surface disease exacerbation are mainly reduced blink rate and completeness, partial/uncorrected refractive error and/or underlying binocular vision anomalies, together with the cognitive demand of the task and differences in position, size, brightness and glare compared to an equivalent non-digital task. In general, interventions are not well established; patients experiencing digital eye strain should be provided with a full refractive correction for the appropriate working distances. Improving blinking, optimizing the work environment and encouraging regular breaks may help. Based on current, best evidence, blue-light blocking interventions do not appear to be an effective management strategy. More and larger clinical trials are needed to assess artificial tear effectiveness for relieving digital eye strain, particularly comparing different constituents; a systematic review within the report identified use of secretagogues and warm compress/humidity goggles/ambient humidifiers as promising strategies, along with nutritional supplementation (such as omega-3 fatty acid supplementation and berry extracts).

Blue-blocking filters do not alleviate signs and symptoms of digital eye strain.

CLINICAL RELEVANCE: There is some controversy about the utility of prescribing blue-blocking filters to mitigate digital eye strain. We found that using commercially available blue-blocking filters was ineffective in reducing orbicularis oculi muscle activity and visual symptomatology during a 30-min reading task from a computer screen. BACKGROUND: There are some claims that blue-blocking (B-B) filters may be effective in reducing symptoms and signs of digital eye strain. However, recent studies have suggested that there is no sufficient evidence to support their use. This study assessed the short-term effects of a commercially available, B-B filter on orbicularis oculi (OO) muscle activity and symptoms of digital eye strain during the execution of a 30-min reading tas. METHODS: Twenty-three healthy young adults (22.9 ± 3.2 years of age) performed two reading tasks from a computer screen with or without a B-B filter on two different days. OO muscle activity was recorded by surface electromyography 4-5, 9-10, 14-15, 19-20, 24-25 and 29-30 min into the trial. Participants reported their perceived levels of visual discomfort and activation before and after completing the reading task. RESULTS: A Bayesian analysis favoured the null hypothesis that there was no change in OO muscle activity with or without using the B-B filter (Bayes Factor01 [BF01] = 7.08). Regarding symptomatology, the analysis favoured the time model that reading increased visual fatigue and discomfort but reduced activation levels (BF01 < 0.33 in all cases). However, our data did not support the alternative model that using B-B filter affected these visual symptoms. CONCLUSIONS: The B-B filter did not alter OO muscle activity or visual symptomatology significantly during the execution of a 30-min reading task in asymptomatic subjects. These findings support the idea that B-B filters do not attenuate signs and symptoms of digital eye strain.

Is critical flicker-fusion frequency a valid measure of visual fatigue? A post-hoc analysis of a double-masked randomised controlled trial.

PURPOSE: Critical flicker-fusion frequency (CFF) has been used in clinical studies as a measure of visual fatigue. We examine the correlation between CFF and subjective reports of visual fatigue in a group of symptomatic computer users, to consider whether CFF may be used as a surrogate measure of visual fatigue symptoms. METHODS: We analysed data from a previous randomised controlled trial. One hundred and twenty adults, diagnosed with computer vision syndrome, had CFF and visual fatigue symptoms quantified before and after a visually demanding 2-h computer task. Symptoms were assessed using a questionnaire with nine subcomponents that summed to a total score of 900. CFF was measured using a two-interval forced-choice method, with the flicker rate altered by a computer-controlled staircase procedure. For our primary analysis, we determined Spearman correlation coefficients between post-task symptom scores and CFF, and between change from baseline symptom scores and CFF. We also used a bootstrap procedure to consider whether symptom score subcomponents were significantly (Bonferroni-corrected) different from overall scores with regard to their correlations with CFF. RESULTS: Although visual fatigue symptom scores altered significantly post-task (mean change: 92 units; 95% confidence interval [CI]: 11 to 122), CFF did not (mean change -0.7 Hz; 95% CI: -1.7 to 0.3). There was no significant correlation between overall symptom scores and CFF, either for the post-task (r = -0.13; 95% CI: -0.31 to 0.05) or the change from baseline (r = -0.18; 95% CI: -0.35 to 0.01) analysis. Subcomponents of the symptom questionnaire did not show a significant correlation with CFF, either for the post-task or the change from baseline analysis. CONCLUSIONS: We find that CFF is not a useful surrogate for symptoms of visual fatigue, given its low correlation with scores on a visual fatigue symptom questionnaire.

Evaluation of VDT-Induced Visual Fatigue by Automatic Detection of Blink Features.

This study evaluates the progression of visual fatigue induced by visual display terminal (VDT) using automatically detected blink features. A total of 23 subjects were recruited to participate in a VDT task, during which they were required to watch a 120-min video on a laptop and answer a questionnaire every 30 min. Face video recordings were captured by a camera. The blinking and incomplete blinking images were recognized by automatic detection of the parameters of the eyes. Then, the blink features were extracted including blink number (BN), mean blink interval (Mean_BI), mean blink duration (Mean_BD), group blink number (GBN), mean group blink interval (Mean_GBI), incomplete blink number (IBN), and mean incomplete blink interval (Mean_IBI). The results showed that BN and GBN increased significantly, and that Mean_BI and Mean_GBI decreased significantly over time. Mean_BD and Mean_IBI increased and IBN decreased significantly only in the last 30 min. The blink features automatically detected in this study can be used to evaluate the progression of visual fatigue.

Refractive and Binocular Vision Status and Associated Asthenopia among Clinical Microscopists.

Background Clinical microscopists are at a greater risk of developing binocular vision anomalies and asthenopia. Objective To assess the refractive and binocular vision status and to explore the association between the presence of asthenopic symptoms and microscopy work among clinical microscopists working at medical laboratory department. Method This cross-sectional study involved 37 clinical microscopists working at medical laboratory department of Dhulikhel Hospital, Nepal. The study was conducted from January to December 2013. Only those participants who had been using microscope for at least a year were enrolled in this study. Each participant underwent distance visual acuity (VA) assessment, refractions, and orthoptic evaluation, including measurement of distance and near phoria, near point of convergence (NPC), near point of accommodation (NPA), positive fusional vergence (PFV), adduction, and calculation of accommodation convergence/accommodation (AC/A) ratio. The tear test was also carried out in each subject. Information about use of glasses, microscopy work (duration, and time spent per day in microscope), and visual symptoms associated with the use of microscope such as eye strain, headache, double vision, and near vision were collected. Result The mean age of the clinical microscopists was 29 ± 5.7 years. The prevalence of refractive error was 56.76% and the mean spherical equivalent (SE) refractive error was -0.77 ± 0.86 D. Refractive error had neither correlation with microscopy work and asthenopic symptoms associated with it, and nor with binocular vision parametersNPC, AA and AC/A ratio. However, there was a positive association between asthenopic symptoms and microscopy work. There was statistically significant difference between symptomatic and asymptomatic subjects for binocular vision parameters, including NPC, AA and positive fusional vergence (PFV) for near. Conclusion Microscopy work has an impact on near binocular vision. Asthenopic symptoms bear a positive association with microscopy work. Refractive error has no significant correlation with either microscopy works or associated asthenopic symptoms.

Investigation of Weighted Scales for Measuring Visual Fatigue in Screening Tasks.

The "screening" trend of modern society has been a progressively increasing burden on the human visual system, and visual fatigue problems are attracting growing attention. Nowadays, subjective testing is the most widely used measure for visual fatigue; however, the low accuracy of subjective testing has been hindering its further improvement. Motivated by the idea of weighted scoring, this study investigated the effects of two weighted scales for measuring visual fatigue in screening tasks. Specifically, a questionnaire with 10 items collected from the classic scales was performed with eye-tracking testing in two typical screen visual fatigue experiments, i.e., searching and watching. Then the subjective scores were factor-analyzed into three subscales before attempting linear regression analyses, which set the dependents to two previously validated eye-tracking parameters, i.e., fixation frequency and saccade amplitude. Finally, two weighted scales were obtained in assessing visual fatigue of varying levels, which demonstrated the potential to improve testing accuracy of visual fatigue with the calibration of objective measurement.

[Digital eye strain. Symptoms, prevalence, pathophysiology, and management]. / Perturbations oculaires secondaires à l'utilisation de supports numériques. Symptômes, prévalence, physiopathologie et prise en charge.

The digital revolution, which has been underway since the 1980's, is disrupting our daily routines with an exponential increase in the use of screens, which has not been without consequence to our visual system. Digital eye strain (DES), or computer vision syndrome (CVS), includes all the visual symptoms secondary to the use of digital devices. DES is present in at least 50% of regular users of digital media and is defined by blurred vision, difficulty focusing, ocular irritation or burning, dry eye, visual fatigue, headaches and increased sensitivity to light. Exposure time, age, female gender, and work environment are the main factors increasing its prevalence. Its pathophysiology, still poorly understood, is felt to be multifactorial and includes disturbances in the accommodative-convergence balance and changes in the ocular surface. Regarding accommodation and convergence, the studies are mostly old and their results heterogeneous. Conversely, many studies have shown an increase in the prevalence of dry eye in screen users. Although the retinal toxicity of blue light has been proven in in vitro models, the low level of evidence in the available studies does not allow it to be clearly correlated with the symptoms of DES. The objective of this review is to condense the knowledge available in the literature on the symptoms, prevalence, pathophysiology and management of DES.

[COMPUTER VISION SYNDROME].

INTRODUCTION: Computer vision syndrome (CVS) is a very common phenomenon amongst computer users. A total of 90% of computer users, who spend more than 3 hours a day in front of the computer screen, suffer from CVS. CVS is also known as digital eye strain or visual fatigue and includes symptoms that are a result of continuous work in front of the different types of computer screens or other types of digital screens. An updated differentiation divides the cause of the symptoms into three separate categories which include visual symptoms, symptoms resulting from the digital screen itself and symptoms resulting from the ocular surface. CVS includes a wide range of symptoms which are non-specific (asthenopia), which include eye fatigue, eye strain, pain in and around the eye, blurred vision, headaches and even diplopia (double vision). Asthenopia and dry eye are the core symptoms of CVS. There are many solutions and ways to treat the different symptoms related to the vision, the screen and ocular surface and especially the symptoms related to the issue of dry eye. The treatment of CVS is focused around the different groups of symptoms and it is recommended to give a combined treatment for all the symptomatic groups. The correction of residual astigmatism, accommodation issues, base-in or base-up prisms and the correction of vergence reserves to maintain vision aspects. Changing the lighting, correct positioning of the screen and correcting the direction of gaze in relation to symptoms which are connected to the screen and artificial tears, as well as increasing the blink rate and increasing the level of moisture of the air in the room, all assist in treating the symptoms of dry eye. Blue light also has some effect on CVS and as a precaution it is recommended to reduce, as much as possible, blue light radiation that enters the eye or is emitted from the computer screen.

[A new valid and reliable questionnaire of asthenopia: development and evaluation].

Objective: To design a valid and reliable questionnaire to determine various causes of asthenopia for use by clinicians and researchers. Methods: The items to be included in the first version questionnaire were selected based on its definition and literature review. The second version was improved from patients interviews and the Delphi method. In this phase, 17 experts, 97 patients [47 males, 50 females, age (34.42±14.62) years old] with asthenopia and 20 controls [9 males, 11 females, age (33.50±7.31) years old] were involved to generated item list. In the Validation phase, we conducted two round interview through 275 asthenopia patients [97 males,186 females,age (34.42±14.62) years old] and 49 controls [17 males,32 females,age (35.79±8.88) years old]for item reduction and questionnaire validity and reliability assessment. Exploratory factor analysis was performed to reduce items and derive the subscale that each item belongs to. Internal consistency was calculated for all resulting subscales, using Cronbach's α coefficient, spilt-half reliability and repeatability. The repeatability of the questionnaire was measured by Pearson correlation analysis. Results: Our initial questionnaire contained 52 symptoms and 2 self-evaluation questions. After the item reduction and assessment, 19 items were selected and classified into three domains through factor analysis. Cronbach α for the three subscales of this version was between 0.79 and 0.85, while for the complete questionnaire it was 0.90, with a spilt-half reliability of 0.80. Factor analysis showed the three components had eigenvalues>3 and these explained 54.3% of the variance. Conclusions: The 19-item asthenopia questionnaire has acceptable psychometric properties, making it a valid and reliable tool for ophthalmologists and optometrists to evaluate asthenopia as well as to seek causes. It has the potential to be used in clinical trials and outcome research. (Chin J Ophthalmol, 2021, 57:284-291).

Do Blue-blocking Lenses Reduce Eye Strain From Extended Screen Time? A Double-Masked Randomized Controlled Trial.

PURPOSE: To investigate if blue-blocking lenses are effective in reducing the ocular signs and symptoms of eye strain associated with computer use. DESIGN: Double-masked, randomized controlled trial. METHODS: A total of 120 symptomatic computer users were randomly assigned (1:1) into a "positive" or "negative" advocacy arm (ie, a clinician either advocating or not advocating for the intervention via a prerecorded video). Participants were further sub-randomized (1:1) to receive either clear (placebo) or blue-blocking spectacles. All participants were led to believe they had received an active intervention. Participants performed a 2-hour computer task while wearing their assigned spectacle intervention. The prespecified primary outcome measures were the mean change (post- minus pre-computer task) in eye strain symptom score and critical flicker-fusion frequency (CFF, an objective measure of eye strain). The study also investigated whether clinician advocacy of the intervention (in a positive or negative light) modulated clinical outcomes. RESULTS: All participants completed the study. In the primary analysis, for CFF, no significant effect was found for advocacy type (positive or negative, p = .164) and spectacle intervention type (blue-blocking or clear lens, p = .304). Likewise, for eye strain symptom score, no differences were found for advocacy (p = .410) or spectacle lens types (p = .394). No adverse events were documented. CONCLUSIONS: Blue-blocking lenses did not alter signs or symptoms of eye strain with computer use relative to standard clear lenses. Clinician advocacy type had no bearing on clinical outcomes.

Astenopia digital em controladores de tráfego aéreo: diagnóstico e avaliação na Força Aérea Portuguesa / Digital-related eye strain in air traffic control specialists: diagnosis and evaluation in the Portuguese Air Force staff

RESUMO A função de controlador aéreo exige várias horas de visualização de ecrãs, o que torna esses profissionais um grupo particularmente exposto à astenopia digital. Procuramos, com este artigo de revisão, compreender quais os métodos quantitativos e qualitativos usados atualmente para diagnosticar e avaliar a fadiga ocular em controladores de tráfego aéreo. Trata-se de pesquisa bibliográfica utilizando as bases de dados PubMed® e ClinicalKey®, usando palavras-chave, tendo sido selecionados artigos de revisão e estudos observacionais com publicação posterior ao ano 2000, de modo que os termos buscados estivessem no título e/ou resumo do trabalho. Excluímos artigos em línguas que não inglesa. Existem vários métodos para melhor caracterizar a astenopia digital, destacando-se os subjetivos, como questionários, e os objetivos, que procuram, por um lado, diagnosticar o olho seco, bem como alterações da acomodação e da convergência. Da análise efetuada, ressaltou-se uma escassez de estudos prospectivos com Níveis de Evidência moderados e altos relacionados com a aplicação dos vários métodos de diagnóstico. A Computer-Vision Symptom Scale parece ser um questionário confiável e que pode ser aplicado aos controladores de tráfego aéreo, para diagnóstico de astenopia digital. Vários métodos objetivos podem também ser utilizados para essa avaliação, sendo importante, numa fase posterior, aplicar esses dois tipos de métodos de diagnóstico para avaliar a prevalência dessa patologia em controladores de tráfego aéreo.

ABSTRACT The work of air traffic control specialists require several hours looking at screens, and they comprise a group particularly exposed to digital-related eye strain. In this review we aim to understand the quantitative and qualitative methods currently used to diagnose and evaluate asthenopia in air traffic control specialists. A bibliographic search was carried out at the databases PubMed® and ClinicalKey®, using keywords, and selecting review articles and observational studies, dated after 2000, containing the keywords in the title and/o abstract. Articles not published in English were excluded. There are several subjective and objective methods to better describe digital-related eye strain, including questionnaires, aiming to make diagnosis of dry eye disease or changes in accommodation and convergence. From our analysis, there are few prospective studies with moderate and high levels of evidence regarding these diagnostic methods. The Computer-Vision Symptom Scale seems to be a reliable questionnaire to be applied to air traffic control specialists, for diagnosis of digital-related eye strain. Several objective methods can also be employed in this evaluation, and, in a later stage, it will be important to apply both diagnostic methods to evaluate the prevalence of this condition in air traffic control specialists.

An investigation of low power convex lenses (adds) for eyestrain in the digital age (CLEDA) / Investigación sobre las lentes convexas de baja potencia (adiciones) para la fatiga en la era digital (CLEDA)

INTRODUCTION: Digital eye strain (DES; computer vision syndrome) is a common cause of symptoms when viewing digital devices. Low-powered convex lenses (adds) have been recommended for the condition and "accommodative support" designs developed on this premise. The present research reports the extent to which dry eye is present in this population and the effect of convex lenses on symptoms and visual performance. METHODS: The CVS-Q instrument was used to select pre-presbyopic adults with the symptoms of DES. Participants received a full eye examination including an assessment of dry eye with a modified SANDE questionnaire and using DEWS I criteria. The immediate effect of low-powered convex lenses (low adds: +0.50D, +0.75D, +1.25D) was investigated using subjective preference and a double-masked comparison with plano lenses with the Wilkins Rate of Reading Test (WRRT). Throughout this testing, participants wore their full distance refractive correction, based on non-cycloplegic retinoscopy and subjective refraction. RESULTS: The signs and symptoms of dry eye were frequently present. Most participants reported a subjective preference for low adds, with +0.75D the most commonly preferred lens. Low adds (+0.50D and +0.75D; but not +1.25D) were associated with significantly improved performance at the WRRT. One quarter of participants read more than 10% faster with these additional convex lenses. CONCLUSIONS: The study population was aged 20-40y and mostly worked on desktop computers. It is possible that +1.25D add may be more advantageous for people who are older or work more at closer viewing distances. Many symptomatic users of digital devices report a preference for low adds and use of these lenses is often associated with an improvement in reading performance

INTRODUCCIÓN: La fatiga digital (DES; síndrome visual informático) es una causa común de síntomas, a causa de la visualización de dispositivos digitales. Se han recomendado lentes convexas de baja potencia para esta situación, así como diseños de "apoyo acomodativo" desarrollados sobre la base de este principio. Los informes de investigación actuales reportan el alcance de la presencia de ojo seco en esta población, así como el efecto de las lentes convexas en los síntomas y el desempeño visual. MÉTODOS: Se utilizó el instrumento CVS-Q para seleccionar adultos pre-presbiópicos con síntomas de DES. Se realizó un examen visual completo a los participantes, incluyendo valoración de ojo seco con un cuestionario SANDE modificado, y utilizando los criterios DEWS I. Se investigó el efecto inmediato de las lentes convexas de baja potencia (adiciones bajas: +0,50D, +0,75D, +1,25D) utilizando la preferencia subjetiva y una comparación doble ciego con lentes planas mediante la prueba Wilkins Rate of Reading Test (WRRT). A lo largo de esta prueba, los participantes utilizaban su corrección refractiva de distancia completa, basada en retinoscopia no ciclopéjica y refracción subjetiva. RESULTADOS: Los signos y síntomas del ojo seco estuvieron frecuentemente presentes. Muchos participantes reportaron una preferencia subjetiva de bajas adiciones, siendo las lentes de +0,75D las más comúnmente preferidas. Las bajas adiciones (+0,50D y +0,75D, pero no +1,25D) se asociaron a un desempeño significativamente mejorado en la prueba WRRT. Un 25% de los participantes leyeron un 10% más rápido con estas lentes convexas adicionales. CONCLUSIONES: La edad de la población de estudio fue de 20 a 40 años, trabajando la mayoría de dichos sujetos en ordenadores de mesa. Es posible que la adición de +1,25D sea más ventajosa para personas de mayor edad, o que trabajen más con distancias de visualización más próxima. Muchos usuarios de dispositivos digitales sintomáticos reportan una preferencia por bajas adiciones, asociándose a menudo el uso de estas lentes a una mejora del desempeño lector

Assessment of eye fatigue caused by head-mounted displays using eye-tracking.

BACKGROUND: Head-mounted displays (HMDs) and virtual reality (VR) have been frequently used in recent years, and a user's experience and computation efficiency could be assessed by mounting eye-trackers. However, in addition to visually induced motion sickness (VIMS), eye fatigue has increasingly emerged during and after the viewing experience, highlighting the necessity of quantitatively assessment of the detrimental effects. As no measurement method for the eye fatigue caused by HMDs has been widely accepted, we detected parameters related to optometry test. We proposed a novel computational approach for estimation of eye fatigue by providing various verifiable models. RESULTS: We implemented three classifications and two regressions to investigate different feature sets, which led to present two valid assessment models for eye fatigue by employing blinking features and eye movement features with the ground truth of indicators for optometry test. Three graded results and one continuous result were provided by each model, respectively, which caused the whole result to be repeatable and comparable. CONCLUSION: We showed differences between VIMS and eye fatigue, and we also presented a new scheme to assess eye fatigue of HMDs users by analysis of parameters of the eye tracker.

Effects of Optical Correction Method on the Magnitude and Variability of Accommodative Response: A Test-retest Study.

SIGNIFICANCE: The present study addresses the accommodative response and its dependence on the type of optical correction used. The results are discussed relative to their possible implications for myopia progression and visual fatigue. PURPOSE: The accommodative response has been investigated owing to its possible relationship with the onset and progression of myopia and visual fatigue. This study explored the influence of wearing soft contact lenses in comparison with spectacles in terms of magnitude and variability of accommodation. In addition, we analyzed the intersession and intermethod repeatability. METHODS: Dynamic accommodative response was recorded during 30-second epochs, at five different distances (50, 40, 33, 25, and 20 cm), in 21 individuals (mean refractive error ± SD, -0.79 ± 1.39 D) while wearing either soft contact lenses or spectacles on two different days. To assess repeatability, a second identical intervention was conducted. RESULTS: Higher lags of accommodation were obtained with the use of soft contact lenses in comparison with the spectacle condition (P = .04, partial η [ηp] = 0.204), and similarly, a higher variability of accommodation at near distances was found during the soft contact lens measurement (P < .001, ηp = 0.647). There was a strong intersession repeatability at all the distances tested for both optical correction methods. CONCLUSIONS: The higher accommodative lag and fluctuations found while wearing soft contact lenses in comparison with spectacles may help to understand the mechanisms underlying myopia progression and asthenopia. These findings may be also considered when testing the accommodative response in research settings. Our test-retest design confirmed that there is a very good intersession repeatability for all the distances in both optical correction methods.

IR-camera-based measurements of 2D/3D cognitive fatigue in 2D/3D display system using task-evoked pupillary response.

This study was carried out to evaluate a method used to measure three-dimensional (3D) cognitive fatigue based on the pupillary response. This technique was designed to overcome measurement burdens by using non-contact methods. The pupillary response is related to cognitive function by a neural pathway and may be an indicator of 3D cognitive fatigue. Twenty-six undergraduate students (including 14 women) watched both 2D and 3D versions of a video for 70 min. The participants experienced visual fatigue after viewing the 3D content. Measures such as subjective rating, response time, event-related potential latency, heartbeat-evoked potential (HEP) alpha power, and task-evoked pupillary response (TEPR) latency were significantly different. Multitrait-multimethod matrix analysis indicated that HEP and TEPR latency measures had stronger reliability and higher correlations with 3D cognitive fatigue than other measures. TEPR latency may be useful for quantitatively determining 3D visual fatigue, as it can be easily used to evaluate 3D visual fatigue using a non-contact method without measuring burden.

The effects of reflected glare and visual field lighting on computer vision syndrome.

BACKGROUND: Computer vision syndrome is common and affects performance of visual tasks. Background illumination, light source, light compensation, position of the display, contrast and glare are environmental factors associated with computer vision syndrome. The aim of this study is to investigate the effects of reflected glare and visual field lighting on computer vision syndrome. METHODS: In a reflected glare experiment, participants performed a two-hour visual task using a glossy, matte, or glare-free surface display in two visual environments (normal, glare). In a visual field lighting experiment, participants performed the visual task in dim lighting, uneven supplementary lighting, or uniform supplementary lighting. Visual function parameters, including critical fusion frequency, heterophoria, amplitude of accommodation and accommodative facility were evaluated by the investigators and a visual fatigue questionnaire was completed before and after the visual task. Visual performance was also recorded. In addition, the variation of pupil size under different lighting conditions was analysed. RESULTS: Critical fusion frequency was the only visual function parameter which decreased significantly after the visual task. The questionnaire score was significantly higher in a glare environment and was lower when the task was performed using a glare-free display. Visual performance was significantly worse in the glossy display group. The increment in the questionnaire score was smaller in the uniform supplementary lighting group. Visual performance was significantly worse in the dim lighting or uneven supplementary lighting group, but not in the uniform supplementary lighting group. Variation in pupil size was significantly greater in the dim lighting condition than in the supplementary lighting condition. CONCLUSION: Critical fusion frequency is an effective indicator of computer vision syndrome. Glare-free displays could alleviate visual fatigue and preserve visual performance. Uniform supplementary lighting could decrease variation in pupil size and prevent eye strain.