Accumulation of VDT work-related visual fatigue assessed by visual evoked potential, near point distance and critical flicker fusion

Illusory motion and vection induced by a printed static image under flickering ambient light at rates up to 100 Hz

Visual motion signals can produce self-motion perception known as vection in observers. Vection can be generated by illusory motions in the form of global expantion in still images as well as by visual motion signals. The perception of vection can be enhanced by flickering images at a rate of 5 Hz. This study examined the illusory motion and vection induced by a printed static image under flickering ambient light at rates up to 100 Hz. The perception of illusory motion and vection were enhanced by flickering ambient lights at 50, 75, and 100 Hz. The enhancement effect was higher for the flicker rates expected to be detectable by humans. The findings of this study suggest that alternating bright and dark signals to the cone receptors and primary visual cortex trigger perceptions of illusory motions.

Blue Light-Ocular and Systemic Damaging Effects: A Narrative Review

Light is a fundamental aspect of our lives, being involved in the regulation of numerous processes in our body. While blue light has always existed in nature, with the ever-growing number of electronic devices that make use of short wavelength (blue) light, the human retina has seen increased exposure to it. Because it is at the high-energy end of the visible spectrum, many authors have investigated the theoretical harmful effects that it poses to the human retina and, more recently, the human body, given the discovery and characterization of the intrinsically photosensitive retinal ganglion cells. Many approaches have been explored, with the focus shifting throughout the years from examining classic ophthalmological parameters, such as visual acuity, and contrast sensitivity to more complex ones seen on electrophysiological assays and optical coherence tomographies. The current study aims to gather the most recent relevant data, reveal encountered pitfalls, and suggest future directions for studies regarding local and/or systemic effects of blue light retinal exposures.

Effects of diet containing astaxanthin on visual function in healthy individuals: a randomized, double-blind, placebo-controlled, parallel study

Visual display terminal work has increased rapidly in recent years. Loss of visual acuity is an unfortunate associated effect. Here, we performed a randomized, placebo-controlled study in 60 healthy adults. Participants received a diet containing astaxanthin (9 mg/day) or placebo for 6 weeks. Visual acuity, functional visual acuity, and pupil constriction rate were measured before and after visual display terminal work. In participants aged ≥40 years, corrected visual acuity of the dominant eye after visual display terminal work at 6 weeks after intake demonstrated a higher protective effect of astaxanthin in the astaxanthin group vs the control group (p<0.05). In participants aged <40 years, no significant difference was seen between the astaxanthin and control groups. Moreover, no significant difference was found in functional visual acuity and pupil constriction rate between the astaxanthin and control groups. These results suggest astaxanthin reduces oxidative stress caused by visual display terminal work. Age-related reduction in ciliary muscle strength is likely the main detractor of visual acuity. Correspondingly, astaxanthin reduced visual display terminal work-induced visual stress in the middle-aged and elderly. This study was registered in the UMIN-CTR database (UMIN000043089).

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 Impact of Internet and Videogaming Addiction on Adolescent Vision: A Review of the Literature

During the past decade, vision problems that were attributed to the use of electronic screens have gradually shifted from being a workplace health issue to a wider public health issue. “Computer vision syndrome” originally related to the few professionals exposed to long hours of work in front of a computer screen. The widespread use of digital screens in devices used throughout the day have led to the emergence of “digital eye strain” as a new clinical syndrome that affects every individual who spends a large period of time fixated on multiple screens, for work or leisure. A new subcategory, “video game vision” has been proposed to specifically address vision issues related to large periods of continuous use of screen enabled devices in order to play video games. With gaming disorder being included in the next version of the WHO classification of diseases (ICD-11), it is becoming increasingly important to have a clear idea of the impact of this disorder in general health and functioning. At the same time, a number of research studies have reported positive impact of videogame playing on the players vision. This article reviews the latest research studies on the impact of digital screen enabled devices on adolescent vision in light of the increasing reports of internet addiction and gaming disorder while referencing positive findings of videogaming on vision in order to provide a balanced approach and assist with classification, diagnosis and treatment, while providing directions for future research.

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.

Therapeutic Effects of Anthocyanins for Vision and Eye Health

Anthocyanin (AC) is widely used as supplement of eye health in Europe and in East Asia. In this review, I describe AC effects to clarify the mechanism is important in order to understand the effects of AC on vision health. The bioavailability of AC is quite low but, reported as intact form and many kinds of metabolite. And AC passes through the blood-aqueous fluid barrier and blood-retinal barrier. In vitro study, AC had a relaxing effect on ciliary muscle which is important to treat both myopia and glaucoma. And AC stimulate the regeneration of rhodopsin in frog rod outer segment. Furthermore, AC could inhibit the axial length and ocular length elongation in a negative lens-induced chick myopia model. In addition, we summarized clinical studies of AC intake improved dark adaptation and transient myopic shift and the improvement on retinal blood circulation in normal tension glaucoma patients.

Effects of prolonged continuous computer gaming on physical and ocular symptoms and binocular vision functions in young healthy individuals

BACKGROUND AND OBJECTIVE

Addiction to computer gaming has become a social problem in Korea and elsewhere, and it has been enlisted as a mental health disorder by the World Health Organization. Most studies related to computer use and vision have individually assessed physical and ocular symptoms and binocular vision. Accordingly, the present study comprehensively assessed subjective physical and ocular symptoms and functions related to binocular vision after prolonged continuous computer gaming. This study aimed to investigate the effects of prolonged continuous computer gaming on physical and ocular health and visual functions in young healthy individuals.

METHODS

Fifty healthy college students (35 male/15 female), aged 19-35 years old, were enrolled in this study. The inclusion criteria were no binocular vision problems and no reported history of ocular disease. Participants played continuously for 4 h from 6:00 to 10:00 p.m. Physical and ocular symptoms and visual functions such as convergence, accommodation, phoria, and the blink rate were assessed before and after continuous computer gaming for 4 h.

RESULTS

Continuous computer gaming for 4 h resulted in convergence and accommodation disturbances and increased physical and ocular discomfort. Near phoria showed an exophoric shift, whereas distance phoria showed no change. Moreover, the accommodative and vergence facilities and blink rate were significantly decreased. All visual functions recovered to the baseline levels by the following morning.

DISCUSSION

Our findings suggest that excessive and continuous computer gaming impairs visual functions and causes ocular and physical fatigue. Our findings further the understanding of the adverse effects of excessive computer use on physical and ocular health, and adequate breaks are necessary to reduce physical and visual discomfort during computer gaming.

Effect of Heat-Killed Lactobacillus paracasei KW3110 Ingestion on Ocular Disorders Caused by Visual Display Terminal (VDT) Loads: A Randomized, Double-Blind, Placebo-Controlled Parallel-Group Study

BACKGROUND

Visual display terminals (VDTs) emitting blue light can cause ocular disorders including eye fatigue. Some dietary constituents have been reported to be effective in improving ocular disorders while few clinical studies have been performed. We evaluated the effects of heat-killed Lactobacillus paracasei KW 3110 on improving ocular disorders and symptoms of eye fatigue among healthy human subjects with VDT loads.

METHODS

In vitro, the effect of L. paracasei KW3110 on blue light-induced human retinal pigment epithelial (ARPE-19) cell damage. For clinical studies, 62 healthy Japanese volunteers of 35 to 45 years of age who had experienced eye fatigue were randomized into two groups and given a placebo or L. paracasei KW3110-containing supplements for eight weeks. The primary endpoint was changes in VDT load-induced eye fatigue as determined by critical flicker frequency four and eight weeks after the start of supplementation.

RESULTS

In vitro, blue light-induced human retinal cell death was suppressed with the culture supernatants of cells treated with L. paracasei KW3110. In clinical study, the VDT load-induced reduction of critical flicker frequency tended to be milder in the L. paracasei KW3110 group when compared with the placebo group during the fourth week. Subgroup analysis classified by the degree of eye fatigue showed that the VDT load-induced reduction of critical flicker frequency was significantly better in the high-level eye fatigue subjects from the L. paracasei KW3110 group when compared with the placebo group during the fourth week (p = 0.020).

CONCLUSIONS

L. paracasei KW3110 suppressed blue light-induced retinal pigment epithelial cell death. In the clinical study, ingestion of L. paracasei KW3110 had a potential to improve eye fatigue induced by VDT loads especially high levels of eye fatigue. However, further studies should be required to show more dependable clinical efficacy of L. paracasei KW3110.

Tired in the Reading Room: The Influence of Fatigue in Radiology

Commonly conflated with sleepiness, fatigue is a distinct multidimensional condition with physical and mental effects. Fatigue in health care providers and any secondary effects on patient care are an important societal concern. As medical image interpretation is highly dependent on visual input, visual fatigue is of particular interest to radiologists. Humans analyze their surroundings with rapid eye movements called saccades, and fatigue decreases saccadic velocity. Oculomotor parameters may, therefore, be an objective and reproducible metric of fatigue and eye movement analysis can provide valuable insight into the etiology of fatigue-related error.

[Evaluation of Motion Sickness Induced by 3D Video Clips]

The use of stereoscopic images has been spreading rapidly. Nowadays, stereoscopic movies are nothing new to people. Stereoscopic systems date back to 280 A.D. when Euclid first recognized the concept of depth perception by humans. Despite the increase in the production of three-dimensional (3D) display products and many studies on stereoscopic vision, the effect of stereoscopic vision on the human body has been insufficiently understood. However, symptoms such as eye fatigue and 3D sickness have been the concerns when viewing 3D films for a prolonged period of time; therefore, it is important to consider the safety of viewing virtual 3D contents as a contribution to society. It is generally explained to the public that accommodation and convergence are mismatched during stereoscopic vision and that this is the main reason for the visual fatigue and visually induced motion sickness (VIMS) during 3D viewing. We have devised a method to simultaneously measure lens accommodation and convergence. We used this simultaneous measurement device to characterize 3D vision. Fixation distance was compared between accommodation and convergence during the viewing of 3D films with repeated measurements. Time courses of these fixation distances and their distributions were compared in subjects who viewed 2D and 3D video clips. The results indicated that after 90 s of continuously viewing 3D images, the accommodative power does not correspond to the distance of convergence. In this paper, remarks on methods to measure the severity of motion sickness induced by viewing 3D films are also given. From the epidemiological viewpoint, it is useful to obtain novel knowledge for reduction and/or prevention of VIMS. We should accumulate empirical data on motion sickness, which may contribute to the development of relevant fields in science and technology.

Bilberry extract supplementation for preventing eye fatigue in video display terminal workers

OBJECTIVES

To examine the effect of a dietary supplement containing bilberry extract (BE) on eye fatigue induced by acute video display terminal (VDT) loads.

DESIGN AND SETTING

A prospective, randomized, double-blind, placebo-controlled study was performed from August 2012 to February 2013 in the Medical Corporation Jico-kai Yagi Hospital, and the Shinyokohama Shinoharaguchi Orthopedic Surgery and Dermatology Clinic, in Japan.

PARTICIPANTS

Two hundred eighty-one office workers aged 20-40 years that used VDTs were screened by critical flicker fusion (CFF) and near point accommodation (NPA).

INTERVENTION

The participants were randomized to either a BE (480 mg/day) or placebo (vehicle) group, and took allocated capsule, daily, for 8 weeks.

MEASUREMENTS

The CFF, NPA, contrast visual acuity, functional visual acuity, keratoconjunctival epithelial damage, and fluorescein tear film break-up time were examined, and 18 subjective symptoms of eye fatigue were evaluated by questionnaire. Adverse events were reported via medical interviews. Data were collected both before and after VDT load at baseline, and 4, and 8 weeks after daily supplementation with either BE or placebo.

RESULTS

Of 281 participants screened, 88 having relatively lower levels of CFF and NPA were enrolled in the study. Of these, 37 control and 43 BE group subjects completed the study. The VDT load-induced reduction in CFF was alleviated after 8 weeks of BE supplementation (95% confidence interval, 0.10-1.60; p=0.023), in contrast to placebo supplementation, while NPA variation was not. Of the subjective symptoms of eye fatigue, VDT load-induced ocular fatigue sensation, ocular pain, eye heaviness, uncomfortable sensation, and foreign body sensation were mitigated more in the BE group than in the control group, at week 8 (p<0.05). There were no severe adverse events in either group.

CONCLUSIONS

BE supplementation improved some of the objective and subjective parameters of eye fatigue induced by VDT loads.

Effect of Blue Light-Reducing Eye Glasses on Critical Flicker Frequency

PURPOSE

This study aims to evaluate the effect of blocking short-wavelength light on critical flicker frequency (CFF).

DESIGN

This study is a prospective clinical study.

METHODS

Thirty-three participants (17 men and 16 women; age range, 28-39 years) were divided into 3 groups. Each group wore 1 of 3 types of lenses while performing an intensive computer task for 2 hours. To evaluate the effect of blocking short-wavelength light before and after the task, we measured the CFF and evaluated subjective questionnaires. We used the analysis of variance test to examine whether the type of lenses tested affected any of the visual fatigue-related parameters.

RESULTS

The type of lens worn significantly affected the CFF; however, answers to the subjective questionnaires did not differ significantly between the groups. Two of the 13 question items showed a statistical difference between lens transparency and increase in the CFF (lens 3 > lens 2 > lens 1).

CONCLUSIONS

The higher the blocking effect of the lens, the lower the reduction in the CFF, suggesting that blocking short-wavelength light can reduce eye fatigue.

Evaluating the Effectiveness of Using Electroencephalogram Power Indices to Measure Visual Fatigue

Electroencephalography (EEG) is widely used in cognitive and behavioral research. This study evaluates the effectiveness of using the EEG power index to measure visual fatigue. Three common visual fatigue measures, critical-flicker fusion (CFF), near-point accommodation (NPA), and subjective eye-fatigue rating, were used for comparison. The study participants were 20 men with a mean age of 20.4 yr. ( SD = 1.5). The experimental task was a car-racing video game. Results indicated that the EEG power indices were valid as a visual fatigue measure and the sensitivity of the objective measures (CFF and EEG power index) was higher than the subjective measure. The EEG β and EEG α were effective for measuring visual fatigue in short- and long-duration tasks, respectively. EEG β/α were the most effective power indexes for the visual fatigue measure.

Effects of VDT workstation lighting conditions on operator visual workload

Industrial lighting covers a wide range of different characteristics of working interiors and work tasks. This study investigated the effects of illumination on visual workload in visual display terminal (VDT) workstation. Ten college students (5 males and 5 females) were recruited as participants to perform VDT signal detection tasks. A randomized block design was utilized with four light colors (red, blue, green and white), two ambient illumination levels (20 lux and 340 lux), with the subject as the block. The dependent variables were the change of critical fusion frequency (CFF), visual acuity, reaction time of targets detection, error rates, and rating scores in a subjective questionnaire. The study results showed that both visual acuity and the subjective visual fatigue were significantly affected by the color of light. The illumination had significant effect on CFF threshold change and reaction time. Subjects prefer to perform VDT task under blue and white lights than green and red. Based on these findings, the study discusses and suggests ways of color lighting and ambient illumination to promote operators' visual performance and prevent visual fatigue effectively.