Eye-Related Pain Induced by Visually Demanding Computer Work

The impact of remote work using mobile information and communication technologies on physical health: a systematic review

Remote e-working with information and communication technology (ICT) has long been on the rise, with its implementation accelerated by mandatory working from home regulations during the COVID-19 pandemic. This systematic literature review summarises the influencing factors of ICT-based remote e-working (device types, duration of use, user interfaces, etc.) on the physical health (musculoskeletal system and eyes) of knowledge workers. A search in four electronic databases and a manual search in four German journals resulted in 21 articles being included in this review. A bias analysis was conducted for all articles. Unfavourable postures, inappropriate working devices and certain environmental factors may cause a range of physical complaints, even after comparably short periods of time. Mostly, these complaints are greater compared to those experienced when working on a fully equipped stationary computer. Therefore, remote e-working requires careful planning, awareness, and the willingness to embrace working situations that counteract these problems.

Orbicularis oculi muscle activity during computer reading under different degrees of artificially-induced aniseikonia

Background

Aniseikonia is a binocular vision disorder that has been associated with asthenopic symptoms. However, asthenopia has been evaluated with subjective tests that make difficult to determine the level of aniseikonia. This study aims to objectively evaluate the impact of induced aniseikonia at different levels on visual fatigue by measuring the orbicularis oculi muscle activity in the dominant and non-dominant eyes while performing a reading task.

Methods

Twenty-four collegiate students (24.00 ± 3.86 years) participated in this study. Participants read a passage for 7 minutes under four degrees of aniseikonia (0%, 3%, 5% and 10%) at 50 cm. Orbicularis oculi muscle activity of the dominant and non-dominant eye was recorded by surface electromyography. In addition, visual discomfort was assessed after each task by completing a questionnaire.

Results

Orbicularis oculi muscle activity increased under induced aniseikonia (i.e., greater values for the 10% condition in comparison to 0%, and 3% conditions (p = 0.034 and p = 0.023, respectively)). No statistically significant differences were observed in orbicularis oculi muscle activity for the time on task and between the dominant and non-dominant eyes. Additionally, higher levels of subjective visual discomfort were observed for lower degrees of induced aniseikonia.

Conclusion

Induced aniseikonia increases visual fatigue at high aniseikonia degrees as measured by the orbicularis oculi muscle activity, and at low degrees as measured with subjective questionnaires. These findings may be of relevance to better understand the visual symptomatology of aniseikonia.

Decoding visual fatigue in a visual search task selectively manipulated via myopia-correcting lenses

Introduction

Visual fatigue resulting from sustained, high-workload visual activities can significantly impact task performance and general wellbeing. So far, however, little is known about the underlying brain networks of visual fatigue. This study aimed to identify such potential networks using a unique paradigm involving myopia-correcting lenses known to directly modulate subjectively-perceived fatigue levels.

Methods

A sample of N = 31 myopia participants [right eye-SE: -3.77D (SD: 2.46); left eye-SE: -3.75D (SD: 2.45)] performed a demanding visual search task with varying difficulty levels, both with and without the lenses, while undergoing fMRI scanning. There were a total of 20 trials, after each of which participants rated the perceived difficulty and their subjective visual fatigue level. We used representational similarity analysis to decode brain regions associated with fatigue and difficulty, analyzing their individual and joint decoding pattern.

Results and discussion

Behavioral results showed correlations between fatigue and difficulty ratings and above all a significant reduction in fatigue levels when wearing the lenses. Imaging results implicated the cuneus, lingual gyrus, middle occipital gyrus (MOG), and declive for joint fatigue and difficulty decoding. Parts of the lingual gyrus were able to selectively decode perceived difficulty. Importantly, a broader network of visual and higher-level association areas showed exclusive decodability of fatigue (culmen, middle temporal gyrus (MTG), parahippocampal gyrus, precentral gyrus, and precuneus). Our findings enhance our understanding of processing within the context of visual search, attention, and mental workload and for the first time demonstrate that it is possible to decode subjectively-perceived visual fatigue during a challenging task from imaging data. Furthermore, the study underscores the potential of myopia-correcting lenses in investigating and modulating fatigue.

Exploring the Effect of Trataka (A Yogic Cleansing Technique) and Cold Eye Pack on Eye Strain During COVID-19 Pandemic: A Randomized Three-Arm Trial

Objective: Computer vision syndrome is a major global public health concern affecting >60 million individuals globally. Yoga and naturopathy practices can reduce visual fatigue and strain. The present study attempted to explore the effect of trataka that is, a yogic cleansing technique and cold eye pack on visual strain and fatigue. Subjects: Three hundred volunteers from an IT company were recruited following inclusion and exclusion criteria. Intervention: The subjects were randomly distributed in three groups, that is, trataka, cold eye pack, and waitlist control group with an allocation ratio of 1:1:1. Outcome measure: Visual Fatigue Scale and Visual symptoms checklist (VSC) was administered at baseline and end of 2 weeks. Repeated measures analysis of variance (RM-ANOVA) with Bonferroni corrections was used to test the difference across the groups. Results: All the variables were similar at the baseline among the groups. Significant changes in the within-group analysis occurred in both the trataka and cold eye pack groups. The RM-ANOVA revealed significant differences in the VAS and VSC (p = 0.001) and the post hoc analysis suggested that there were significant differences in both the trataka and cold eye pack group when compared with the control group (p = 0.001); however, there was no differences between the trataka and cold eye pack group in both the scales (p = 1). Conclusions: The results of the present study suggest that a trataka and cold eye pack for 14 days improves self-rated visual strain and fatigue among IT professionals with computer vision syndrome. Clinical Trial registration number: CTRI/2020/11/029003.

Visual discomfort and contact lens wear: A review

The purpose of this manuscript is to describe how vision influences contact lens discomfort and review the evidence supporting the hypothesis that contact lens discomfort can be caused by vision and vision-related disorders. Contact lens discomfort is a misunderstood and difficult to manage clinical condition. Most treatments and strategies aimed at alleviating discomfort focus on optimizing the contact lens fit and its relationship with the ocular surface, but these strategies commonly fail at relieving discomfort symptoms. Many vision and vision-related disorders share symptoms with those reported by uncomfortable contact lens wearers. This paper will review evidence and literature that describes how these vision and vision-related disorders may influence comfort in contact lens wearers. Acknowledging how vision influences contact lens discomfort will improve future research intended to better understand the condition, allow for more effective clinical management, and reduce rates of discontinuation.

Unexpected vision performance with photochromic contact lenses in normal and low light conditions: An analysis of two randomized trials

PURPOSE

Evaluate the performance of a photochromic contact lens in various lighting conditions throughout the day, including those indoor and outdoor environments where the photochromic contact lens is in a less active or inactive state.

METHODS

Data from two clinical trials of a photochromic contact lens were analyzed to evaluate its performance in various light environments. Both studies involved a photochromic test lens (ACUVUE® OASYS with Transitions™ Light Intelligent Technology™) and a similar non-photochromic control lens (ACUVUE® OASYS 2-week with HYDRACLEAR® PLUS). The studies were both multi-visit, multi-site, 2-treatment by 3-period randomized crossover (i.e., Test/Control/Control or Control/Test/Test) dispensing studies, with follow-up visits after each 2-week dispensing period.

RESULTS

A total of 250 subjects were dispensed lenses across both studies, of which 237 total subjects completed. In situations where exposure to an activating light source is common (e.g., outdoors), the Test lens was preferred nearly 6:1 over the control lens. In situations where exposure to an activating light source is less common - indoors, driving at night, using digital devices -, the Test lens was still preferred over the control lens by margins of 4:1, nearly 4:1, and over 3:1 respectively. The Test lens was superior with respect to quality of vision, ability to see comfortably, clarity of vision, reduction of squinting while using computers and reduction of bright light while driving at night.

CONCLUSION

The photochromic test contact lens was rated superior to a non-photochromic control lens in environmental situations where the lens is in a less active or inactive state.

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.

The relationship between visual display terminal usage at work and symptoms related to computer vision syndrome

Background

Although it is well known that the usage of visual display terminal (VDT) at the workplace causes computer vision syndrome (CVS), previous studies mainly focused on computer use and the health of white-collar workers. In this study, we explored the relationship between the usage of VDT including various devices, and symptoms related to CVS in a large population including pink-collar workers and blue-collar workers.

Methods

21,304 wage workers over the age of 20 years were analyzed from the 6th Korean Working Conditions Survey. To investigate the association between VDT use at work and symptoms related to CVS among wage workers, odds ratios (ORs) and 95% confidence interval (CI) were calculated by multivariate logistic regression models.

Results

In the group with the highest VDT usage at work, the OR of headache/eyestrain was 2.16 (95% CI: 1.86-2.52). The OR of suspected CVS patients was significantly increased in the highest group of usage of VDT at work (OR: 1.69; 95% CI, 1.39-2.06). Compare with the reference group, the OR for headache/eyestrain in the highest group of VDT usage was 2.81 (95% CI: 2.13-3.70) in white-collar workers, 1.78 (95% CI: 1.32-2.40) in pink-collar workers, and 1.59 (95% CI: 1.18-2.15) in blue-collar workers.

Conclusions

We observed a relationship in which the use of VDT in the workplace increases the risk of headache/eyestrain regardless of occupational classification. Our findings emphasize the importance of paying attention to the health of VDT workers and making plans to improve their working conditions.

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.

Review on the possible pathophysiological mechanisms underlying visual display terminal-associated dry eye disease

BACKGROUND

Visual display terminal (VDT) use is a key risk factor for dry eye disease (DED). Visual display terminal (VDT) use reduces the blink rate and increases the number of incomplete blinks. However, the exact mechanisms causing DED development from VDT use have yet to be clearly described.

PURPOSE

The purpose of the study was to conduct a review on pathophysiological mechanisms promoting VDT-associated DED.

METHODS

A PubMed search of the literature investigating the relationship between dry eye and VDT was performed, and relevance to pathophysiology of DED was evaluated.

FINDINGS

Fifty-five articles met the inclusion criteria. Several pathophysiological mechanisms were examined, and multiple hypotheses were extracted from the articles. Visual display terminal (VDT) use causes DED mainly through impaired blinking patterns. Changes in parasympathetic signalling and increased exposure to blue light, which could disrupt ocular homeostasis, were proposed in some studies but lack sufficient scientific support. Together, these changes may lead to a reduced function of the tear film, lacrimal gland, goblet cells and meibomian glands, all contributing to DED development.

CONCLUSION

Visual display terminal (VDT) use appears to induce DED through both direct and indirect routes. Decreased blink rates and increased incomplete blinks increase the exposed ocular evaporative area and inhibit lipid distribution from meibomian glands. Although not adequately investigated, changes in parasympathetic signalling may impair lacrimal gland and goblet cell function, promoting tear film instability. More studies are needed to better target and improve the treatment and prevention of VDT-associated DED.

The association between visual display terminal use and dry eye: a review

BACKGROUND

Dry eye disease (DED) is a multifactorial disease of the tear film and ocular surface. It causes ocular symptoms, reduced quality of life and a considerable economic burden on society. Prolonged use of visual display terminals (VDTs) has been suggested as an important risk factor for DED.

PURPOSE

This review aims to study the association between DED and VDT use with an emphasis on the prevalence of DED among VDT users and harmful daily duration of VDT use.

METHODS

A PubMed search was conducted and yielded 57 relevant articles based on a set of inclusion and exclusion criteria. The studies were subclassified according to study design.

RESULTS

The far majority of the studies showed an association between VDT use and DED or DED-related signs and symptoms. The prevalence of definite or probable DED in VDT and office workers ranged from 26% to 70%, with as few as 1-2 hr of VDT exposure per day being associated with DED.

CONCLUSION

VDT use is strongly associated with DED. VDT-associated DED is prevalent, but the exact prevalence needs to be further elucidated using standardized DED diagnosis criteria. Furthermore, a safe lower limit of daily VDT use has yet to be established. More research is needed on the effect of digitalization and digital transformation, which are particularly high during the time of the COVID-19 pandemic.

Interventions for the management of computer vision syndrome: a systematic review and meta-analysis

TOPIC

To evaluate the efficacy and safety of interventions for treating eye strain related to computer use relative to placebo or no treatment.

CLINICAL RELEVANCE

Computer use is pervasive and often associated with eye strain, referred to as "computer vision syndrome" (CVS). Currently, there are no clinical guidelines to help practitioners provide evidence-based advice about CVS treatments, many of which are directly marketed to patients. This systematic review and meta-analysis will help inform best practice for eye care providers.

METHODS

Eligible randomized controlled trials (RCTs) were identified in Ovid MEDLINE, EMBASE, CENTRAL, and trial registries, searched from inception to November 23, 2021. Eligible studies were appraised for risk of bias, and synthesized. The certainty of the body of evidence was judged using GRADE. Standardized mean differences (SMD) were used when differently scaled measures were combined.

RESULTS

Forty-five RCTs, involving 4497 participants, were included. Multifocal lenses did not improve visual fatigue scores compared to single-vision lenses (three RCTs, SMD: 0.11; 95% confidence interval (CI) -0.14 to 0.37; p=0.38). Visual fatigue symptoms were not reduced by blue-blocking spectacles (three RCTs), with evidence judged to be of low certainty. Relative to placebo, oral berry extract supplementation for 4 to 12 weeks did not improve visual fatigue (seven RCTs, SMD: -0.27; 95%CI -0.70 to 0.16; p=0.22), and dry eye symptoms (four RCTs, SMD: -0.10; 95%CI -0.54 to 0.33; p=0.65). Likewise, berry extract supplementation had no effect on critical flicker-fusion frequency (CFF) or accommodative amplitude. Oral omega-3 fatty acid supplementation for 45 days to 3 months improved dry eye symptoms (two RCTs, mean difference, MD: -3.36 units out of 18; 95%CI -3.63 to -3.10; p<0.00001) relative to placebo. Oral carotenoid supplementation improved CFF (two RCTs, MD: 1.55 Hz; 95%CI 0.42 to 2.67; p=0.007) relative to placebo, although the clinical significance of this finding is unclear.

CONCLUSIONS

We found no high certainty evidence supporting the use of any of the therapies analyzed. There was low certainty evidence that oral omega-3 supplementation reduces dry eye symptoms in symptomatic computer users.

The role of trataka in ameliorating visual strain and promoting psychological well-being during prolonged use of digital displays: A randomized controlled trial

BACKGROUND: The prolonged usage of digital displays leads to visual strain and, in turn, impairs psychological well-being. The practice of Yoga is said to enhance psychological functions and reduce visual strain. OBJECTIVE: The present study assessed the effect of the trataka (Yogic visual concentration) practice on the visual strain, mind-wandering, and mindfulness. METHODS: One hundred six volunteers equally distributed in the experimental and control groups completed the study. Visual Fatigue Scale (VFS), visual symptoms checklist (VSC), mind-wandering questionnaire (MWQ), and State Mindfulness Attention Awareness Scale (SMAAS) were administered at baseline and at the end of two weeks. RESULTS: All variables were similar at the baseline in both groups, and significant differences were noted at the end of two weeks between both groups. There was a significant reduction in VFS and VSC scores, MWQ, along with an increase in SMAAS scores in the experimental group. Although there were significant changes in VFS, MWQ, and SMAAS in the control group, the magnitude of change was minimal. CONCLUSIONS: The practice of trataka was found to reduce the visual strain, mind wandering while improving the state mindfulness. The practice can be implemented to mitigate visual strain and associated psychological implications due to prolonged exposure to digital displays, which has increased during the COVID-19 pandemic.

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.

High frequency of digital eye strain and dry eye disease in teleworkers during the coronavirus disease (2019) pandemic

Objectives. This study aimed to evaluate visual display terminal (VDT)-related digital eye strain (ES) and dry eye disease (DED) symptoms in subjects whose work was changed to teleworking (TW) during the coronavirus pandemic. Methods. A digital self-reported survey was conducted on subjects in TW, including demographics, medical history, VDT time and ES-related symptoms before and during the pandemic and DED (dry eye questionnaire 5 [DEQ-5] questionnaire). Results. A total of 1797 questionnaires were analyzed. Mean age was 40.5 (SD 11.1) years, and 69.9% were female. The mean number of TW weeks was 10.2 (SD 3.0). The total VDT total hours increased from 7.4 (SD 3.3) to 9.5 (SD 3.3) (p < 0.001). All ES symptoms presented a significant increase (p < 0.001). The mean DEQ-5 score was 8.3 (SD 4.9). The oldest group presented lower values, and women had a higher score (p < 0.001). Additionally, 28.6% of the subjects were classified with severe DED, and the variables associated with a logistic regression model were total VDT hours, female gender, refractive surgery, rosacea, depression, previous DED, keratoconus and blepharitis. Conclusions. The number of VDT hours seemed to be a relevant factor for increase in ES symptoms and a high prevalence of DED during the pandemic period.

Objective and subjective evaluation of tear film in machine carpet weavers

OBJECTIVES

The present study was conducted to evaluate the status of tear film objectively and subjectively in machine carpet weavers.

METHODS

In this cross-sectional study, machine-made carpet weavers were compared with the controls who were selected from people working in other parts of the factory except for the production. A complete evaluation of ocular health was done for all participants. The blink rate, tear deformation Time (TDT), and ocular staining were evaluated as an objective assessment and the ocular surface disease index (OSDI) was used for a subjective assessment of the tear film status. The results were compared between the two groups using the SPSS software.

RESULTS

The results of 46 weavers (mean age: 38.43 ± 6.10 years) and 46 controls (mean age: 33.20 ± 8.40 years) were analyzed. The mean of blink rate and OSDI score were significantly higher in weavers (Blink rate: 20.67 ± 4.18 blink/min, OSDI: 22.59 ± 9.51) in comparison with controls (Blink rate: 14.00 ± 3.30 blink/min, OSDI: 6.22 ± 4.78, P < .001). The mean TDT value of the weavers was significantly lower compared with the controls (10.27 ± 3.01 and 16.58 ± 4.18 s respectively, P < .001). Ocular surface staining was seen among 60.9% of weavers while there was 6.5% in the controls (P < .001). Based on the TDT test and OSDI results together, the percentage of dry eye in the weavers was 43.5% and that in the non-weavers was 2.2%, which showed that the relationship between weaving and dry eyes was statistically significant (P < .001).

CONCLUSIONS

The results indicate that increased symptoms and decreased tear stability in weavers compared with non-weavers lead to more tear film abnormalities in these individuals.

The Effects of Chewing Gum in Preventing Eyestrain

Purpose

To investigate the effects of chewing gum and tablet candy to reduce eyestrain in healthy individuals.

Materials and Methods

A double-blinded crossover trial was conducted. Forty-six healthy individuals (23 men, 23 women) between 20 and 59 years old, feeling eyestrain, were enrolled. Each 10-year age group included 12 individuals except the 30s group, which included 10 individuals. A visual task was performed on reading material displayed on a computer screen at a fixed distance for 60 min. Gum or tablet candy of two pieces were chewed for two 15-min periods starting 15 and 45 min after starting to read. Subjects chewed gum on Day 1 and tablet candy on Day 2, and vice versa. Primary outcome is as follows: subjective eye fatigue (eye tiredness, eye heaviness, blurred vision, double vision, and eye dryness) using a visual analog scale (VAS). Secondary outcomes are as follows: subjective accommodation from near and far points of accommodation measured with a D'ACOMO, spherical equivalent refraction, and eye dryness by analyzing ring break-up time (RBUT) measured with the RT-7000 Auto Ref-Topographer.

Results

The VAS scores of subjective eye fatigue were not significantly changed between chewing gum and tablet candy (P = 0.397 − P = 0.909). Those scores of eye tiredness and eye heaviness were significantly longer before and after the visual task with tablet candy (P = 0.013 and P = 0.025, respectively) but not with chewing gum. The changes of subjective accommodation were significantly lower after the visual task between chewing gum and candy (P = 0.043). There were significant differences among each age group (20 s vs. 30 s, P = 0.594; 20 s vs. 40 s, P = 0.002; 20 s vs. 50 s, P = 0.002). After reading, the changes of spherical equivalent refraction did not indicate a shift toward myopia (P = 0.267). In the RBUT, there were no significant differences between the samples (P = 0.680).

Conclusions

Chewing gum helps improve the ability of the eye to focus, especially in young adults.

An Eye-tracking based Evaluation on the Effect of Far-infrared Therapy for Relieving Visual Fatigue

Far-infrared (FIR) therapy is attracting great attention in clinical applications, whereas studies on its effect to relieve visual fatigue stay exiguity. This study tried to fill the gap by utilizing two novel eye-tracking parameters, i.e., the fixation frequency (FF) and saccade amplitude (SA), along with traditional indicators (i.e., the eye blink frequency (BF) and subjective score (SS)) of visual fatigue in two eye-tracking tests, i.e., the random digit search and fixed-point gaze. Twenty healthy subjects participated in the experiment during the same period of two consecutive days. A visual stimulus program was presented to each subject before the subjective grading and eye-tracking tests, followed by the relief of eyes with either using a FIR thermal eye mask or physically closing eyes. Finally, subjective grading and eye-tracking tests were re-performed. Results showed that FF and SA, along with BF and SS, were significantly different when measured before and after the eye relief with FIR therapy mask, suggesting that FF and SA were useful in evaluating visual fatigue. In addition, FIR therapy yielded much better performance than eye-closing rest, indicating that FIR therapy had the potential in accelerating the relief of visual fatigue.

Computer vision symptoms in people with and without neck pain

BACKGROUND

Sixty-four to 90% of computer users experience symptoms of computer vision syndrome (CVS). People with CVS symptoms experience neck pain (NP), and people with NP can have visual symptoms.

OBJECTIVES

(1) To examine differences in CVS symptoms in computer users with and without persistent NP. (2) To determine relationships between visual ergonomics, demographics, and CVS in those with and without persistent NP DESIGN: Comparative cross-sectional observational study METHOD: An online survey consisting of multiple questionnaires including the Computer Vision Syndrome Questionnaire (CVS-Q), Visual Symptoms Survey (VSS), and Convergence Insufficiency Symptoms Survey (CISS) was completed by 167 participants.

RESULTS

The persistent NP group had significantly higher CVS-Q, VSS, and CISS scores (p <0.01) compared to controls. No relationships were found between visual ergonomics, demographics, and visual symptoms in both groups.

CONCLUSIONS

People with persitent NP are more likely to present with CVS than controls. Clinicians should consider assessing visual symptoms in people presenting with persisting NP.

Video Display Operator Complaints: A 10-Year Follow-Up of Visual Fatigue and Refractive Disorders

Visual fatigue and discomfort are very common complaints for video display operators (VDTs). The aim of our study was to study work-related visual symptoms in relation to refractive disorders and psychosocial factors in 3054 public employees by way of follow-ups for 10 years with periodic medical examinations with eye evaluation in the period 2000-2009. Factors related to visual fatigue were evaluated in the follow-up using generalized equation estimation. Visual fatigue was very common in VDT operators (64.03%). During the follow-up, no relationship between visual fatigue and age, sex, seniority of work, visual acuity and refractory disorders was found. Visual fatigue was significantly associated with anxiety perception in a dose-related matter (odds ratio (OR) 7.40, confidence interval (CI) 95% 1.77-31.3), psychosocial factors (OR 1.03, CI 95% 1.01-1.07), use of lenses (OR 1.34, CI 95% 1.09-1.64) and time of VDT usage (OR 1.27, CI 95% 1.04-1.53). This study confirmed that visual fatigue is common in VDT users and is related to anxiety perception, time of VDT usage, use of lenses and stress. No relationship was found between visual fatigue and refractory disorders or visual acuity.

Discomfort glare and psychological stress during computer work: subjective responses and associations between neck pain and trapezius muscle blood flow

PURPOSE

Exposure to additional environmental stress during computer work, such as visual and psychological demands, is associated with increased eye and neck discomfort, altered moods, and reduced well-being. The aim of this study is to elucidate further how subjective responses in healthy, young females with normal binocular vision are affected by glare and psychological stress during computer work, and to investigate possible associations between trapezius muscle blood flow and neck pain development.

METHODS

43 females participated in a laboratory experiment with a within-subject design. Four 10-min computer work conditions with exposure to different stressors were performed at an ergonomically optimal workstation, under the following series of conditions: no additional stress, visual stress (induced as direct glare from a large glare source), psychological stress, and combined visual and psychological stress. Before and immediately after each computer work condition, questionnaires regarding different visual and eye symptoms, neck and shoulder symptoms, positive and negative state moods, perceived task difficulty, and perceived ambient lighting were completed. Associations between neck pain and trapezius muscle blood flow were also investigated.

RESULTS

Exposure to direct glare induced greater development of visual/eye symptoms and discomfort, while psychological stress exposure made participants feel more negative and stressed. The perception of work lighting during glare exposure was closely related to perceived stress, and associations between visual discomfort and eyestrain, and neck pain were observed in all conditions. Furthermore, participants with high trapezius muscle blood flow overall reported more neck pain, independent of exposure.

CONCLUSIONS

Exposure to visual and psychological stresses during computer work affects the development of symptoms and negative moods in healthy, young females with normal binocular vision, but in different ways. The results also demonstrate the complex interactions involved in symptom development and lighting appraisal during computer work. When optimizing computer workstations, the complexity of the field must be taken into account, and several factors, including visual conditions, must be considered carefully.

Accommodative asthenopia among Romanian computer-using medical students-A neglected occupational disease

Computers have become to play an important role in people's lives throughout the world thus increasing the number of patients with ocular complaints. Also known as computer vision syndrome, accommodative asthenopia might be considered as a neglected occupational condition, but there is no consensus regarding diagnostic criteria, which leads to under-recognition and under-reporting. The aim of the study was to investigate the prevalence, early symptoms and specific preventive measures of accommodative asthenopia among computer-using medical students (n = 420), in a cross-sectional study. The most common early symptoms were: tired eyes/eye strain (86.1%), burning eyes (46.8%), migraines/headaches (46.8%), red-swollen eyes (43%), photophobia (41.8%), temporary blurred vision (35.4%), and eyelid spasms (32.9%). Our study identifies the most frequent early symptoms of accommodative asthenopia as a possible occupational disease, which might serve as a fundament for a future consensus strategy.

Correlation between handheld digital device use and asthenopia in Chinese college students: a Shanghai study

PURPOSE

The purpose of this study was to investigate the use of handheld digital devices and the prevalence of self-reported asthenopia among college students in China and their potential relationship.

METHODS

Five thousand students were randomly assessed using a self-reported asthenopia questionnaire. The students' demographic characteristics and habits regarding digital device use were recorded. Univariate analysis was performed to select potential risk factors, and multivariate logistic regression was used to estimate the odds ratios for the selected risk factors of interest.

RESULTS

Among the 4786 students who completed the survey, the prevalence of asthenopia was 53.3%. Multivariate analysis revealed significant relationships between asthenopia and each of the following: level of digital reliance (OR 1.350, 95%CI: 1.230-1.481), workload, time spent on computer per day, sex and time spent on handheld digital devices in bed and at desk. Aerobic exercise duration (OR 0.912, 95%CI: 0.839-0.990) was found to be strong predictor of less asthenopia complaints.

CONCLUSION

Asthenopia appears to be common among college students in China. Preventative measures against asthenopia include limiting the amount of time spent using digital devices in bed (<0.5 h), adopting a posture of lying on one's back while doing so and engaging in aerobic exercise for more than one hour per day. Furthermore, studies on this topic are needed.

Blind working time in visual display terminal users

OBJECTIVES

Blind working (BW) time (time during which vision is not required), the interblink interval (IBI), and subjective symptoms were investigated in workers using visual display terminals (VDTs).

SUBJECTS AND METHODS

To investigate BW time, 10 VDT users were instructed to close their eyes when this did not interfere with their work. They were video recorded for 60 minutes using a webcam attached to the display on which they were engaged in regular data input tasks, and BW time was measured. The values of the IBI during the final 20 minutes of the BW experiment and during the final 20 minutes of normal working without BW were compared. A questionnaire was administered to investigate subjective symptoms using a visual analogue scale.

RESULTS

The total BW time during the final 20-minute period was 20.6-121.0 seconds (1.7%-10.1%). The mean IBI of 5.5 ± 4.5 seconds during the BW experiment was not significantly different from that of 6.2 ± 5.6 seconds during normal working, and the mean of three IBIs immediately after BW during the BW experiment was 2.7 ± 1.0 seconds, significantly shorter than the 6.2 ± 5.6 seconds during normal working. Dry eye, ocular fatigue, and blurred vision during normal working improved when subjects were engaged in BW.

CONCLUSIONS

VDT users could engage in BW during VDT work, the IBI was shorter immediately after BW, and subjective symptoms improved. These results suggest that BW may provide a more effective measure for the management of VDT working time.

A Randomized Trial to Evaluate the Effect of Toric Versus Spherical Contact Lenses on Vision and Eyestrain

OBJECTIVES

To compare the effect of toric versus spherical soft contact lenses on objective measures of visual performance using visual acuity and electromyography of the orbicularis oculi muscle.

METHODS

Current soft contact lens wearers with -0.75 to -1.75 D astigmatism in each eye were binocularly fitted with toric (1-Day ACUVUE MOIST for astigmatism) and spherical (1-Day ACUVUE MOIST) contact lenses in random order. After each fitting and at 1-week follow-up, high- and low-contrast visual acuities were measured. Electromyography was used to objectively evaluate eyestrain. Linear mixed models were used to assess differences between toric and spherical contact lenses.

RESULTS

The mean age (±SD) of the 60 participants was 27.5±5.0 years, spherical refractive error was -3.68±2.01 D, and cylinder was -1.28±0.36 D. High- and low-contrast visual acuities with toric lenses were better than with spherical lenses at both fitting (toric high-contrast: -0.065±0.078 and low-contrast: 0.133±0.103 vs. spherical high-contrast: 0.001±0.104 and low-contrast: 0.224±0.107) and follow-up (toric high-contrast: -0.083±0.087 and low-contrast: 0.108±0.107 vs. spherical high-contrast: -0.015±0.095 and low-contrast: 0.211±0.104) (all P<0.0001). Electromyography-measured eyestrain was less with toric versus spherical contact lenses at fitting (least-square ratio of toric over spherical=0.72; P=0.0019) but not at follow-up (ratio=0.86; P=0.11).

CONCLUSION

These results suggest that toric contact lenses provided improved objective measures of vision in a low-to-moderate astigmatic population.

Visual and psychological stress during computer work in healthy, young females-physiological responses

Purpose

Among computer workers, visual complaints, and neck pain are highly prevalent. This study explores how occupational simulated stressors during computer work, like glare and psychosocial stress, affect physiological responses in young females with normal vision.

Methods

The study was a within-subject laboratory experiment with a counterbalanced, repeated design. Forty-three females performed four 10-min computer-work sessions with different stress exposures: (1) minimal stress; (2) visual stress (direct glare); (3) psychological stress; and (4) combined visual and psychological stress. Muscle activity and muscle blood flow in trapezius, muscle blood flow in orbicularis oculi, heart rate, blood pressure, blink rate and postural angles were continuously recorded. Immediately after each computer-work session, fixation disparity was measured and a questionnaire regarding perceived workstation lighting and stress was completed.

Results

Exposure to direct glare resulted in increased trapezius muscle blood flow, increased blink rate, and forward bending of the head. Psychological stress induced a transient increase in trapezius muscle activity and a more forward-bent posture. Bending forward towards the computer screen was correlated with higher productivity (reading speed), indicating a concentration or stress response. Forward bent posture was also associated with changes in fixation disparity. Furthermore, during computer work per se, trapezius muscle activity and blood flow, orbicularis oculi muscle blood flow, and heart rate were increased compared to rest.

Conclusions

Exposure to glare and psychological stress during computer work were shown to influence the trapezius muscle, posture, and blink rate in young, healthy females with normal binocular vision, but in different ways. Accordingly, both visual and psychological factors must be taken into account when optimizing computer workstations to reduce physiological responses that may cause excessive eyestrain and musculoskeletal load.

Management of digital eye strain

Digital eye strain, an emerging public health issue, is a condition characterised by visual disturbance and/or ocular discomfort related to the use of digital devices and resulting from a range of stresses on the ocular environment. This review aims to provide an overview of the extensive literature on digital eye strain research with particular reference to the clinical management of symptoms. As many as 90 per cent of digital device users experience symptoms of digital eye strain. Many studies suggest that the following factors are associated with digital eye strain: uncorrected refractive error (including presbyopia), accommodative and vergence anomalies, altered blinking pattern (reduced rate and incomplete blinking), excessive exposure to intense light, closer working distance, and smaller font size. Since a symptom may be caused by one or more factors, a holistic approach should be adopted. The following management strategies have been suggested: (i) appropriate correction of refractive error, including astigmatism and presbyopia; (ii) management of vergence anomalies, with the aim of inducing or leaving a small amount of heterophoria (~1.5^Δ Exo); (iii) blinking exercise/training to maintain normal blinking pattern; (iv) use of lubricating eye drops (artificial tears) to help alleviate dry eye-related symptoms; (v) contact lenses with enhanced comfort, particularly at end-of-day and in challenging environments; (vi) prescription of colour filters in all vision correction options, especially blue light-absorbing filters; and (vii) management of accommodative anomalies. Prevention is the main strategy for management of digital eye strain, which involves: (i) ensuring an ergonomic work environment and practice (through patient education and the implementation of ergonomic workplace policies); and (ii) visual examination and eye care to treat visual disorders. Special consideration is needed for people at a high risk of digital eye strain, such as computer workers and contact lens wearers.

Symptomatic accommodative and binocular dysfunctions from the use of flat-panel displays

AIM

To determine the presence of symptomatic accommodative and non-strabismic binocular dysfunctions (A_NSBD) in a non-presbyopic population of video display unit (VDU) users with flat-panel displays.

METHODS

One hundred and one VDU users, aged between 20 to 34y, initially participated in the study. This study excluded contact-lens wearers and subjects who had undergone refractive surgery or had any systemic or ocular disease. First, subjects were asked about the type and nature of eye symptoms they experienced during VDU use. Then, a thorough eye examination excluded those subjects with a significant uncorrected refractive error or other problem, such as ocular motility disorders, vertical deviation, strabismus and eye diseases. Finally, the remaining participants underwent an exhaustive assessment of their accommodative and binocular vision status.

RESULTS

Eighty-nine VDU users (46 females and 43 males) were included in this study. They used flat-panel displays for an average of 5±1.9h a day. Twenty subjects presented A_NSBD (22.5%). Convergence excess was the most frequent non-strabismic binocular dysfunction (9 subjects), followed by fusional vergence dysfunction (3 subjects) and convergence insufficiency (2 subjects). Within the accommodative dysfunctions, accommodative excess was the most common (4 subjects), followed by accommodative insufficiency (2 subjects). Moderate to severe eye symptoms were found in 13 subjects with A_NSBD.

CONCLUSION

Significant eye symptoms in VDU users with accommodative and/or non-strabismic binocular dysfunctions often occur and should not be underestimated; therefore, an appropriate evaluation of accommodative and binocular vision status is more important for this population.

Effectiveness of a participatory eye care program in reducing eye strain among staff computer users in Thailand

BACKGROUND

The increased usage of computers results in a variety of health problems, particularly eye strain, which is the most common workplace complaint today.

OBJECTIVES

This study aimed to evaluate the effectiveness of a participatory eye care (PEC) program by comparing eye care knowledge, attitude, and practice (KAP), as well as eye strain symptoms in staff computer users at Sukhothai Thammathirat Open University, Thailand.

METHODS

A participatory approach was held by organizing a meeting of 26 stakeholders to get opinions for developing the PEC program. The developed PEC program consisted of 3-hour training course on eye strain, rest breaks for 30 seconds every 30 minutes of computer use, and 15-minute rest break (in the morning and the afternoon) with integrated eye-neck exercises. Then, a quasi-experiment was conducted to evaluate the effectiveness of the PEC program. A total of 35 staff computer users enrolled in each of intervention and control groups for 8 weeks. Chi-square test and repeated measures analysis of variance were used for comparison of eye strain symptoms and the KAP scores.

RESULTS

The intervention was associated with reduction in percentage of eye strain. Significant differences were found between the intervention and the control groups at follow-up 1 (χ²=18.529, p-value <0.001) and follow-up 2 (χ²=18.651, p-value <0.001). The PEC program likely increased the beneficial effect on KAP scores between the groups and between times (p<0.05).

CONCLUSION

The findings currently provide evidence to support a practical program developed through a participatory approach, which both researchers and computer users could apply to reduce eye strain.

Visual consequences of electronic reader use: a pilot study

BACKGROUND

With the increasing prevalence of electronic readers (e-readers) for vocational and professional uses, it is important to discover if there are visual consequences in the use of these products. There are no studies in the literature quantifying the incidence or severity of eyestrain, nor are there clinical characteristics that may predispose to these symptoms with e-reader use.

PURPOSE

The primary objective of this pilot study was to assess the degree of eyestrain associated with e-reader use compared to traditional paper format. The secondary outcomes of this study were to assess the rate of eyestrain associated with e-reader use and identify any clinical characteristics that may be associated with the development of eyestrain.

METHODS

Forty-four students were randomly assigned to study (e-reader iPAD) and control (print) groups. Participant posture, luminosity of the room, and reading distance from reading device were measured during a 1-h session for both groups. At the end of the session, questionnaires were administered to determine symptoms.

RESULTS

Significantly higher rates of eyestrain (p = 0.008) and irritation (p = 0.011) were found among the iPAD study group as compared to the print 'control' group. The study group was also 4.9 times more likely to report severe eyestrain (95 % CI [1.4, 16.9]). No clinical characteristics predisposing to eyestrain could be identified.

CONCLUSIONS

These findings conclude that reading on e-readers may induce increased levels of irritation and eyestrain. Predisposing factors, etiology, and potential remedial interventions remain to be determined.

Evaluation of 'I-Preventive': a digital preventive tool for musculoskeletal disorders in computer workers-a pilot cluster randomised trial

OBJECTIVES

I-Preventive is a digital preventive tool for musculoskeletal disorders (MSDs) in computer workers. We sought to determine its impact on pain in computer workers with upper limb MSDs and visual discomfort.

METHODS

We conducted a pilot cluster randomised trial in 2 different sites of a tyre factory in France. We randomised 200 employees to either an intervention group (I-Preventive) or control group, each comprising symptomatic and asymptomatic employees. The workers were followed up for 5 months. The main outcome was overall recovery from symptoms following 1 month's intervention based on Nordic-style and eyestrain questionnaires.

RESULTS

We included 185/200 workers: 96 in the intervention group (mean age 41.8±1.4 years; 88.5% males) and 79 in the control group (mean age 42.9±12.0 years; 94.5% males). The most painful areas (numerical scale ≥2) were the neck (40.0%), upper back (18.8%) and shoulders (15.7%). For the most painful anatomical area, the Nordic score significantly decreased after 1 month in the intervention group (p=0.038); no change was observed in the control group (p=0.59). After 1 month's use, the intervention group reported less pain in the painful area and less visual discomfort symptoms (p=0.02). Adherence to the I-Preventive program was 60%.

CONCLUSIONS

I-Preventive is effective in the short term on musculoskeletal symptoms and visual discomfort by promoting active breaks and eyestrain treatment. This easy-to-use digital tool allows each worker to focus on areas of their choice via personalised, easy exercises that can be performed in the workplace.

TRIAL REGISTRATION NUMBER

NCT02350244; Pre-results.

Visual and ocular effects from the use of flat-panel displays

AIM

To evaluate the prevalence of eye symptoms in a non-presbyopic population of video display unit (VDU) users with flat-panel displays.

METHODS

One hundred and sixteen VDU users with flat-panel display from an urban population participated in the study; their ages ranging from 20 to 34y. There were 60 females and 56 males. An eye examination to rule out the presence of significant uncorrected refractive errors, general binocular dysfunctions and eye conditions was carried out. In order to determine and quantify the type and nature of eye symptoms, participants were asked to answer written questionnaire and the results were grouped by gender, age and number of hours a day spent using a VDU.

RESULTS

Seventy-two percent of participants reported eye symptoms related to VDU use. Eye symptoms from moderate-to-severe were found in 23% of participants. The main symptom was moderate-to-severe tired eyes (14%); followed by sensitivity to bright lights (12%), blurred vision at far distances (10%), eyestrain or dry eye or irritated or burning eyes (9%), difficulty in refocusing from one distance to another or headache (8%) and blurred vision at near or intermediate distances (<4%). Eye symptoms were greater among females (P=0.005) and increased with VDU use, markedly above 6h spent using a VDU in a typical day (P=0.01).

CONCLUSION

Significant eye symptoms relate to VDU use often occur and should not be underestimated. The increasing use of electronic devices with flat-panel display should prompt users to take appropriate measures to prevent or to relieve the eye symptoms arising from their use.

Reading from computer screen versus reading from paper: does it still make a difference?

Four experiments were conducted to test whether recent developments in display technology would suffice to eliminate the well-known disadvantages in reading from screen as compared with paper. Proofreading speed and performance were equal for a TFT-LCD and a paper display, but there were more symptoms of eyestrain in the screen condition accompanied by a strong preference for paper (Experiment 1). These results were replicated using a longer reading duration (Experiment 2). Additional experiments were conducted to test hypotheses about the reasons for the higher amount of eyestrain associated with reading from screen. Reduced screen luminance did not change the pattern of results (Experiment 3), but positioning both displays in equal inclination angles eliminated the differences in eyestrain symptoms and increased proofreading speed in the screen condition (Experiment 4). A paper-like positioning of TFT-LCDs seems to enable unimpaired reading without evidence of increased physical strain. Practitioner Summary: Given the developments in screen technology, a re-assessment of the differences in proofreading speed and performance, well-being, and preference between computer screen and paper was conducted. State-of-the-art TFT-LCDs enable unimpaired reading, but a book-like positioning of screens seems necessary to minimise eyestrain symptoms.

Reducing Short-Wavelength Blue Light in Dry Eye Patients with Unstable Tear Film Improves Performance on Tests of Visual Acuity

Purpose

To investigate whether suppression of blue light can improve visual function in patients with short tear break up time (BUT) dry eye (DE).

Methods

Twenty-two patients with short BUT DE (10 men, 12 women; mean age, 32.4 ± 6.4 years; age range, 23–43 years) and 18 healthy controls (10 men, 8 women; mean age, 30.1 ± 7.4 years; age range, 20–49 years) underwent functional visual acuity (VA) examinations with and without wearing eyeglasses with 50% blue light blocked lenses. The functional VA parameters were starting VA, functional VA, and visual maintenance ratio.

Results

The baseline mean values (logarithm of the minimum angle of resolution, logMAR) of functional VA and the visual maintenance ratio were significantly worse in the DE patients than in the controls (P < 0.05), while no significant difference was observed in the baseline starting VA (P > 0.05). The DE patients had significant improvement in mean functional VA and visual maintenance ratio while wearing the glasses (P < 0.05), while there were no significant changes with and without the glasses in the control group (P > 0.05),

Conclusions

Protecting the eyes from short-wavelength blue light may help to ameliorate visual impairment associated with tear instability in patients with DE. This finding represents a new concept, which is that the blue light exposure might be harmful to visual function in patients with short BUT DE.

Advanced dry eye screening for visual display terminal workers using functional visual acuity measurement: the Moriguchi study

PURPOSE

To evaluate the validity of a dry eye (DE) screening method in visual display terminal (VDT) workers using functional visual acuity (VA) measurement combined with a symptoms questionnaire, and to make recommendations regarding practical use of the screening.

METHODS

This prospective cross-sectional study included 369 young and middle-age office workers, who use VDTs. Subjects completed two types of DE questionnaires and underwent DE testing and functional VA measurement. Subjects were assigned to DE and non-DE groups. Sensitivity and specificity of the DE prediction value were assessed. According to the probability distribution of DE and non-DE calculated by the discriminant analysis formula, we classified subjects into three categories based on the most appropriate cut-off levels. Positive predictive value (PPV) and negative predictive value (NPV) of the DE prediction value were also assessed.

RESULTS

Of 369 subjects, 218 and 151 subjects were assigned to the DE and non-DE groups, respectively. Sensitivity and specificity were 93.1% and 43.7%, respectively. Based on the probability prediction, the cut-off levels were defined as probability prediction ≥ 85%, 45% ≤ probability prediction < 85% and probability prediction < 45%. Subjects with a probability prediction ≥ 85% were defined positive (N = 130), while those with values < 45% were defined as negative (N = 73). The PPV and NPV were 83.8% and 80.8%, respectively.

CONCLUSIONS

Acceptable PPV and NPV were obtained by setting three discriminate categories. This improved version of the DE screening method may be acceptable for practical use in VDT workers.

Comparison of Orbicularis Oculi Muscle Activity during Computer Work with Single and Dual Monitors

[Purpose] This study compared the orbicularis oculi muscle activity during computer work with single and dual monitors. [Subjects] Ten computer workers 22–27 years of age were included in this study. [Methods] Subjects performed computer work with single or dual monitors, and the activity of the right orbicularis oculi muscle was measured with a MP150 system. [Results] The muscle activity of the orbicularis oculi under condition 1 was significantly decreased compared with that under conditions 2 or 3. The muscle activity of the orbicularis oculi under condition 3 was significantly increased compared with that under condition 2. [Conclusion] The present study found that the use of dual monitors increased orbicularis oculi activity; therefore, to decrease eye fatigue in computer users, computer workstations that use either a single monitor, or identical monitors from the same manufacturer in a dual setup, are recommended.

Reliability of muscle blood flow measurements in orbicularis oculi

PURPOSE

Orbicularis oculi muscle tension and muscle blood flow have been shown to be objective measures of eyestrain during visually demanding activities, such as computer work. In line with this, positive associations between eye-related pain and muscle blood flow in orbicularis oculi have been observed. A hypothesis regarding work situations with cognitive tasks and low-level muscle activity, such as computer work, proposes that muscle pain originates from the blood vessel-nociceptor interactions of the connective tissue of the muscle. Noninvasive muscle blood flow measurements in the orbicularis oculi muscle are preferable to using an invasive technique. The aim of this study was to test reproducibility and stability of muscle blood recordings in orbicularis oculi using photoplethysmography.

METHODS

In the reproducibility tests, 12 subjects were tested twice within 1 to 5 weeks. To study the stability of the method, six of the subjects were randomly selected and tested four more times within 2 to 6 weeks. Test subjects were doing identical visually demanding computer work for 10 minutes in each test.

RESULTS

The short-term repeatability of muscle blood flow measurements was considered good, but the stability of blood flow recordings over time in orbicularis oculi was low because of a greater within-subject maximum variability compared with between-subject average variability.

CONCLUSIONS

Investigators should be aware of the effect of time, possibly attributed to confounding factors such as environmental changes and mental stress, when comparing photoplethysmography muscle blood flow recordings.

Prevalence of asthenopia and its risk factors in Chinese college students

AIM

To determine the prevalence of asthenopia and identify any associated risk factors in the college students in Xi'an, China.

METHODS

From April to September 2012, 1 500 students from five universities in Xi'an were selected according to a multi-stage stratified cluster sampling method. Data on demographic features, lifestyle or dietary habits, health status, living environment conditions, sleep and mental status, and asthenopia symptoms were collected through a self-administered validated questionnaire. Univariate logistic regression and multivariate logistic regression analysis modified by the factor analysis were performed to evaluate risk factors for asthenopia.

RESULTS

Fifty-seven percent of the college students complained of asthenopia. Statistically significant risk factors for asthenopia in the univariate analysis included 13 variables. Multivariate analysis revealed a significant relationship between the use of computer and asthenopia (OR 1.21, 95%CI: 1.09 to 1.35). Good sleep and mental status (OR 0.86, 95%CI: 0.76 to 0.97), good living environment conditions (OR 0.67, 95%CI: 0.60 to 0.76), and high intake of green leafy vegetables (OR 0.89, 95%CI: 0.80 to 0.98) were found to be strong predictors of decreasing the occurrence of asthenopia complaints.

CONCLUSION

Asthenopia symptom appears to be common among college students; and it is strongly associated with computer use, psychosocial state, environment conditions and dietary habits, suggesting that additional studies are warranted to verify these risk factors and establish prevention guidelines, especially for college students.

Computer-related visual symptoms in office workers

PURPOSE

Many individuals report visual symptoms during office work and specifically computer use. This study determined the prevalence of symptoms in a population of office workers, and examined the association between these symptoms and both dry eye disease and other demographic factors.

METHOD

A written questionnaire was used to quantify the prevalence of symptoms in 520 New York City office workers, and to determine the effect of risk factors including gender, ethnicity, age, smoking, type of refractive correction and hours spent doing computer work. The questionnaire also examined the prevalence of ocular surface disease.

RESULTS

A significant positive correlation was observed between the symptom score and the number of hours spent working on a computer in a typical day. The most prevalent symptom was tired eyes, which was reported by approximately 40% of subjects as occurring 'at least half the time'. 32% and 31% of subjects reported symptoms of dry eye and eye discomfort, respectively. Symptoms varied significantly with gender (being greater in females), ethnicity (being greater in Hispanics) and the use of rewetting drops. A significant positive correlation was observed between computer-related visual symptoms and the Ocular Surface Disease Index (OSDI), a measure of dry eye.

CONCLUSIONS

Visual symptoms associated with computer use occur frequently in the general population producing discomfort for extended periods of time. They are strongly associated with ocular surface disease. Therapeutic regimens need to be developed for this widespread condition.