Computer Vision Syndrome

Published Literature On Accommodation & Vergence Anomalies

Title : Digital visual training helps treat disorders associated with close work

Authors: Ms Faiza Bhombal, Mr Md Oliullah Abdal, Dr Gul Nankani, and Dr David P. Piñero


In the presence of CVS, it is important to conduct a complete accommodative and binocular vision assessment as an anomaly in these aspects can contribute significantly to symptomatology compatible with CVS. If a binocular or accommodative disorder is detected, it can be managed successfully with visual training. The Bynocs platform can be helpful for this purpose, facilitating a significant reduction of the asthenopia score and a significant improvement of the subject’s binocular and accommodative abilities. This platform is a cloud-based software for assessment and management in binocular vision disorders, only requiring the use of a computer or laptop with internet connectivity, a pair of anaglyph and flippers. The use of this option has several advantages, such as the use of engaging activities and a real-time control of compliance, allowing a successful home-based treatment. More studies are needed in the future, including a multicentric longitudinal randomized double blinded trial, to investigate further the efficacy of the visual therapy with this online visual training platform.

Title: Accommodative anomalies in  children

Authors: Juanita D. Collier, O.D., and Mark Rosenfield, M.C.Optom., Ph.D.

Our group has reported that approximately 80% of outpatient visits in the pediatric ophthalmology department in March and April 2020 (at the start of the lockdown) were refractive errors, of which 79% were for myopia. With no definitive end in sight for the pandemic, we are potentially facing an explosive scenario of this “quarantine myopia.” There are predictions of a worsening of the myopic epidemic worldwide and is estimated that over 50% of the world’s population will have myopia by 2050. Besides myopic progression, accommodative dysfunction in children is also on the rise due to digital device usage.

Accommodation spasms and sudden onset esotropia are important causes. The former presents with an acute, rapid increase in myopia and requires dynamic, cycloplegic retinoscopy, and a comprehensive assessment of the binocular visual field. Receded near the point of convergence, large near exophoria, reduced near the point of accommodation, and lag of accommodation greater than +1.25 diopter sphere demand further assessment for non-strabismic binocular vision dysfunction. Vision therapy plays a significant role in managing these anomalies.

Title: Impact of the COVID-19 pandemic on digital eye strain in children

Authors: Jayadev, Chaitra; Sarbajna, Puja; Vinekar, Anand


The authors have highlighted the impact of increasing usage of digital devices during the ongoing COVID-19 pandemic on ocular health in an online survey conducted for adults.[1] Whereas there is no arguing about the ill-effects of this phenomenon in adults owing to changes forcefully affected by the lockdown, an equally or perhaps a more vulnerable cohort that is silently suffering this onslaught of increased digital device use, are children. Children today are growing up in an increasingly visually demanding world. Electronic devices, video games, e-readers, tablets, and laptops, and the ubiquitous mobile phone were already exploited for entertainment and leisure. The COVID-19 pandemic has increased this burden by leaving schools with no choice but to adapt to e-learning platforms. Children now spend an average of 8–12 h a day on some form of digital device. This has increased the threat of digital eye strain (DES), making it an emerging public health problem with an estimated prevalence in the community reported between 22.3% and 39.8%.[2]

Title: Unexpectedly high prevalence of asthenopia in Australian school children identified by the CISS survey tool

Authors: Barbara M. Junghans, Serap Azizoglu, and Sheila G. Crewther


Background : To date there have been few systematic attempts to establish the general prevalence of asthenopia in unselected populations of school-aged children. Thus, the aim of this study was to determine whether the incorporation of Borsting et al’s 2003 Revised Convergence-Insufficiency Symptom Survey (CISS) into a general school vision screening could aid in the identification of children with visual discomfort and indicate the need for further investigation.

Methods : Vision screening of an unselected middle school population investigated and analysed the incidence of self-reported nearwork-related visual discomfort via the CISS along with distance and near visual acuities plus non-cycloplegic autorefraction using a Shin-Nippon NVision-K 5001.

Results : Of the 384 unselected students approached in Grades 6-9, 353 participated (92.2%, mean 13.2 ± 1.4 years). The mean CISS score for the population without amblyopia and/or strabismus (96.0% of all students) was 16.8 ± 0.6, i.e., 45% of students in this cohort had CISS scores greater than one standard deviation above the mean found by Borsting et al. in 2003 during their validation study of the CISS on 9 to 18 year old children without binocular anomalies. Regression analyses indicated significantly higher (p < 0.001) mean CISS scores for the 3.2% who were hyperopes ?+ 2.00D by non-cycloplegic autorefraction (27.7 ± 14.7) and for those who were amblyopic (24.3 ± 6.6) or strabismic (34.0 ± 9.8). The mean CISS score of 31.6 ± 9.0 for non-amblyopic/strabismic students having near vision poorer than 0.1 LogMAR was significantly higher (p < 0.001) than for those with good acuity.

Conclusion : The most important finding of this study was the high incidence of asthenopia in an unselected population and that refractive status per se was not a major contributor to CISS scores. The results highlight the usefulness of the CISS questionnaire for assessment of visual discomfort in school vision screenings and the need for future exploration of near binocular vision status as a potential driver of asthenopia in school students, especially given current trends for frequent daily use of computers and handheld devices and necessarily prolonged accommodative-convergence effort at near, both at school and at home.

Title: Binocular and Accommodation Problems Associated With Computer Use

Authors: N/A


Among the most frequent health-related problems reported by users of computer video display terminals (VDTs) are those related or attributed to vision. Working on the computer for long periods can lead to blurred vision, eye discomfort, fatigue, and headaches.1 When patients seek care for complaints related to computer use, it is important to accurately diagnose and treat all of their symptoms, not only the visual problems. Symptoms associated with VDT use can roughly be categorized into four primary areas—refractive, binocular vision, ocular and systemic health, and ergonomic. Symptoms resulting from each of these can be resolved with proper care and attention to environmental design.

Incidence of Computer Use

Nearly 15% of patients seeking general eye care schedule their visual examination as a result of computer-related visual complaints.2 This is not surprising as 70 million U.S. households (62%) contained one or more computers in 2003, a number which increased to 91.7 million households (76.7%) by 2010.3 Surveys indicate that, although more than 10% of patients present with symptoms primarily associated with computer use, more than 20% could not receive a definitive diagnosis and treatment plan.4

According to the U.S. Census Bureau, in 2010, 68% of Americans aged 15 and older used computers at home, 35% used computers at work, and 15% used computers at school.3 Utilization of digital devices, particularly mobile media, has increased substantially in recent years.5 In 2016, approximately two-thirds of American adults aged 30 to 49 years spent five or more hours on digital devices6 and in the UK, adults spent nearly 5 hours per day using digital media.? In older age groups, use of technology also grew rapidly; between 2011 and 2017, the population classed as “recent Internet users” (within the last 3 months) more than doubled in the 75 years and over age group, and increased from 52.0% to 77.5% in those aged 65 to 74 years.8 Recent U.S. data indicate that 37% of adults aged 60 years and over spend five or more hours per day using digital devices. This age group prefers desktops and laptops for Internet browsing, whereas younger adults tend to use smartphones.6 Multitasking with digital devices is prominent among adults aged 20 to 29 years with 87% reporting simultaneous use of two or more digital devices.6

Title: Computer vision syndrome: a review of ocular causes and potential treatments

Authors: By Bynocs0, Mark Rosenfield


Computer vision syndrome (CVS) is the combination of eye and vision prob- lems associated with the use of computers. In modern western society the use of computers for both vocational and avocational activities is almost universal. However, CVS may have a significant impact not only on visual comfort but also occupational productivity since between 64% and 90% of computer users expe- rience visual symptoms which may include eyestrain, headaches, ocular discom- fort, dry eye, diplopia and blurred vision either at near or when looking into the distance after prolonged computer use. This paper reviews the principal ocular causes for this condition, namely oculomotor anomalies and dry eye. Accommo- dation and vergence responses to electronic screens appear to be similar to those found when viewing printed materials, whereas the prevalence of dry eye symp-toms is greater during computer operation. The latter is probably due to a decrease in blink rate and blink amplitude, as well as increased corneal exposure resulting from the monitor frequently being positioned in primary gaze. How- ever, the efficacy of proposed treatments to reduce symptoms of CVS is unpro- ven. A better understanding of the physiology underlying CVS is critical to allow more accurate diagnosis and treatment. This will enable practitioners to opti- mize visual comfort and efficiency during computer operation.

Title: Digital eye strain: prevalence, measurement and & amelioration

Authors: Amy L Sheppard, James S Wolffsohn


Digital device usage has increased substantially in recent years across all age groups, so that extensive daily use for both social and professional purposes is now normal. Digital eye strain (DES), also known as computer vision syndrome, encompasses a range of ocular and visual symptoms, and estimates suggest its prevalence may be 50% or more among computer users. Symptoms fall into two main categories: those linked to accommodative or binocular vision stress, and external symptoms linked to dry eye. Although symptoms are typically transient, they may be frequent and persistent, and have an economic impact when vocational computer users are affected. DES may be identified and measured using one of several available questionnaires, or objective evaluations of parameters such as critical flicker—fusion frequency, blink rate and completeness, accommodative function and pupil characteristics may be used to provide indices of visual fatigue. Correlations between objective and subjective measures are not always apparent. A range of management approaches exist for DES including correction of refractive error and/or presbyopia, management of dry eye, incorporating regular screen breaks and consideration of vergence and accommodative problems. Recently, several authors have explored the putative role of blue light-filtering spectacle lenses on treating DES, with mixed results. Given the high prevalence of DES and near-universal use of digital devices, it is essential that eye care practitioners are able to provide advice and management options based on quality research evidence.

Title: Prevalence of non-strabismic anomalies of binocular vision in Tamil Nadu: report 2 of BAND study

Authors: Jameel Rizwana Hussaindeen MPhil FCOVD-I FAA(), Archayeeta Rakshit MPhil, Neeraj Kumar Singh MPhil Ronnie George, MS Meenakshi Swaminathan, MS Suman Kapur5 PhD, Mitchell Scheiman OD, Krishna Kumar Ramani PhD

Background: Population-based studies on the prevalence of non-strabismic anomalies of binocular vision in ethnic Indians are more than two decades old. Based on indigenous normative data, the BAND (Binocular Vision Anomalies and Normative Data) study aims to report the prevalence of non-strabismic anomalies of binocular vision among school children in rural and urban Tamil Nadu. 


Methods: This population-based, cross-sectional study was designed to estimate the preva-lence of non-strabismic anomalies of binocular vision in the rural and urban population of Tamil Nadu. In four schools, two each in rural and urban arms, 920 children in the age range of seven to 17 years were included in the study. Comprehensive binocular vision assessment was done for all children including evaluation of vergence and accom-modative systems. In the first phase of the study, normative data of parameters of binocu-lar vision were assessed followed by prevalence estimates of non-strabismic anomalies of binocular vision. 


Results: The mean and standard deviation of the age of the sample were 12.7 ± 2.7 years. The prevalence of non-strabismic anomalies of binocular vision in the urban and rural arms was found to be 31.5 and 29.6 per cent, respectively. Convergence insufficiency was the most prevalent (16.5 and 17.6 per cent in the urban and rural arms, respectively) among all the types of non-strabismic anomalies of binocular vision. There was no gender predilection and no statistically significant differences were observed between the rural and urban arms in the prevalence of non-strabismic anomalies of binocular vision (Z-test, p > 0.05). The prevalence of non-strabismic anomalies of binocular vision was found to be higher in the 13 to 17 years age group (36.2 per cent) compared to sewn to 12 years (25.1 per cent) (Z-test, p < 0.05). 


Conclusion: Non-strabismic binocular vision anomalies are highly prevalent among school children and the prevalence increases with age. With increasing near visual demands in the higher grades, these anomalies could significantly impact the reading efficiency of children. Thus, it is recommended that screening for anomalies of binocular vision should be integrated into the conventional vision screening protocol. 

Title: Computer Vision Syndrome (a.k.a digital eye strain)

Authors: Mark Rosenfield MCOptom PhD FAAO


Computer vision syndrome, also known as digital eye strain, is the combination of eye and vision problems associated with the use of computers (including desktop, laptop and tablets) and other electronic displays (eg smartphones and electronic reading devices). In today’s world, the viewing of digital screens for both vocational and avocational activities is virtually universal. Digital electronic displays differ significantly from printed materials in terms of the within-task symptoms experienced. Many individuals spend 10 or more hours per day viewing these displays, frequently without adequate breaks. In addition, the small size of some portable screens may necessitate reduced font sizes, leading to closer viewing distances, which will increase the demands on both accommodation and vergence. Differences in blink patterns between hard-copy and electronic displays have also been observed. Digital eye strain has been shown to have a significant impact on both visual comfort and occupational productivity, since around 40% of adults and up to 80% of teenagers may experience significant visual symptoms (principally eye strain, tired and dry eyes), both during and immediately after viewing electronic displays. This paper reviews the principal ocular causes for this condition, and discusses how the standard eye examination should be modified to meet today’s visual demands. It is incumbent upon all eye care practitioners to have a good understanding of the symptoms associated with, and the physiology underlying problems while viewing digital displays. As modern society continues to move towards even greater use of electronic devices for both work and leisure activities, an inability to satisfy these visual requirements will present significant lifestyle difficulties for patients.

Title: Computer vision syndrome among computer office workers in a developing country: an evaluation of prevalence and risk factors

Authors: P. Ranasinghel*O, W. S. Wathurapathal, Y. S. Perera, D. A. Lamabadusuriya, S. Kulatunga, N. Jayawardana and P. Katulanda



Background : Computer vision syndrome (CVS) is a group of visual symptoms experienced in relation to the use of computers. Nearly 60 million people suffer from CVS globally, resulting in reduced productivity at work and reduced quality of life of the computer worker. The present study aims to describe the prevalence of CVS and its associated factors among a nationally-representative sample of Sri Lankan computer workers. 


Methods : Two thousand five hundred computer office workers were invited for the study from all nine provinces of Sri Lanka between May and December 2009. A self-administered questionnaire was used to collect socio-demo-graphic data, symptoms of CVS and its associated factors. A binary logistic regression analysis was performed in all patients with ‘presence of CVS’as the dichotomous dependent variable and age, gender, duration of occupation, daily computer usage, pre-existing eye disease, not using a visual display terminal (VDT) filter, adjusting brightness of screen, use of contact lenses, angle of gaze and ergonomic practices knowledge as the continuous/dichotomous independent variables. A similar binary logistic regression analysis was performed in all patients with ‘severity of CVS’ as the dichotomous dependent variable and other continuous/dichotomous independent variables. 


Results : Sample size was 2210 (response rate-88.4 %). Mean age was 30.8 ± 8.1 years and 50.8 % of the sample were males. The 1-year prevalence of CVS in the study population was 67.4 %. Female gender (OR: 1.28), duration of occupation (OR: 1.07), daily computer usage (1.10), pre-existing eye disease (OR: 4.49), not using a VDT filter (OR: 1.02), use of contact lenses (OR: 3.21) and ergonomics practices knowledge (OR: 1.24) all were associated with significantly presence of CVS. The duration of occupation (OR: 1.04) and presence of pre-existing eye disease (OR: 1.54) were sig-nificantly associated with the presence of ‘severe CVS 


Conclusions : Sri Lankan computer workers had a high prevalence of CVS. Female gender, longer duration of occupa-tion, higher daily computer usage, pre-existing eye disease, not using a VDT filter, use of contact lenses and higher ergonomics practices knowledge all were associated with significantly with the presence of CVS. The factors associ-ated with the severity of CVS were the duration of occupation and presence of pre-existing eye disease.

Title : Accommodation and convergence during sustained computer work

Authors: Juanita D. Collier, O.D., and Mark Rosenfield, M.C.Optom., Ph.D.


Purpose : With computer usage becoming almost universal in contemporary society, the reported prevalence of computer vision syndrome (CVS) is extremely high. However, the precise physiological mechanisms underlying CVS remain unclear. Although abnormal accommodation and vergence responses have been cited as being responsible for the symptoms produced, there is little objective evidence to support this claim. Accordingly, this study measured both of these oculomotor parameters during a sustained period of computer use.

Methods : Subjects (N 5 20) were required to read text aloud from a laptop computer at a viewing distance of 50 cm for a sustained 30-minute period through their habitual refractive correction. At 2-minute intervals, the accommodative response (AR) to the computer screen was measured objectively using a Grand Seiko WAM 5500 optometer (Grand Seiko, Hiroshima, Japan). Additionally, the vergence response was assessed by measuring the associated phoria (AP), i.e., prism to eliminate fixation disparity, using a customized fixation disparity target that appeared on the computer screen. Subjects were asked to rate the degree of difficulty of the reading task on a scale from 1 to 10.

Results : Mean accommodation and AP values during the task were 1.07 diopters and 0.74Δ base-in (BI), respectively. The mean discomfort score was 4.9. No significant changes in accommodation or vergence were observed during the course of the 30-minute test period. There was no significant difference in the AR as a function of subjective difficulty. However, the mean AP for the subjects who reported the least and greatest discomfort during the task was 1.55Δ BI and 0, respectively (P 5 0.02).

Conclusions : CVS, after 30 minutes was worse in subjects exhibiting zero fixation disparity when compared with those subjects having a BI AP but does not appear to be related to differences in accommodation. A slightly reduced vergence response increases subject comfort during the task.