[Chinese expert consensus on the diagnosis and treatment of asthenopia (2024)].

Asthenopia is a group of eye discomfort syndromes with complex clinical manifestations, accompanied with systemic symptoms or not. It is caused by diverse influencing factors and occurs upon overuse of the eyes. Over the past decade, significant changes have appeared in the etiology, clinical manifestation and treatment of asthenopia with great changes in the society and lifestyles. The Chinese Optometric Association of Chinese Ophthalmological Society and the Optometry Group of Chinese Ophthalmologist Association have organized nationwide experts in the field to thoroughly discuss the latest researches on asthenopia. Consensus opinions have been formed on the causes, influencing factors, clinical manifestations, diagnosis and treatment of asthenopia, following the definition of asthenopia in the International Classification of Diseases, so as to provide guidance for the clinical diagnosis and treatment of asthenopia.

Digital eye strain in young screen users: A systematic review.

Digital eye strain (DES) or computer vision syndrome (CVS) is a phenomenon linked to ever increasing digital screen use globally, affecting a large number of individuals. Recognizing causative and alleviating factors of DES may help establish appropriate policies. We aimed to review factors that aggravate or alleviate DES symptoms in young, i.e. pre-presbyopic (< 40 years old), digital device users. We searched PubMed, Scopus, EMBASE, Cochrane, Trip Database, and grey literature up to 1st July 2021. Among a plethora of studies with heterogeneous diagnostic criteria for DES, we only included those using a validated questionnaire for the diagnosis and evaluating associated factors in young subjects. Relevant data were extracted, risk of bias assessment of the included studies and GRADE evaluation of each outcome were performed. Ten studies were included (five interventional, five observational) involving 2365 participants. Evidence coming from studies with moderate risk of bias suggested that blue-blocking filters do not appear to prevent DES (2 studies, 130 participants), while use of screens for > 4-5 h/day (2 studies, 461 participants) and poor ergonomic parameters during screen use (1 study, 200 participants) are associated with higher DES symptoms' score. GRADE evaluation for the outcomes of blue-blocking filters and duration of screen use showed low to moderate quality of evidence. It appears advisable to optimize ergonomic parameters and restrict screen use duration, for minimizing DES symptoms. Health professionals and policy makers may consider recommending such practices for digital screen users at work or leisure. There is no evidence for use of blue-blocking filters.

Computer vision syndrome and associated factors in university students and teachers in Nampula, Mozambique.

BACKGROUND: Computer Vision Syndrome (CVS) is a complex of eye and visual problems that arise while using a computer or other Video Display Terminal (DVT). With the advent of the COVID-19 pandemic, the use of these DVTs has become indispensable in the lives of students and teachers. This study aims to identify the prevalence of CVS and associated factors in students and teachers at Lúrio University, in Nampula, during the pandemic period. METHODS: This is a cross-sectional study, carried out between November 2020 and March 2021. The validated CVS questionnaire (CVS-Q) and another semi-structured questionnaire on ergonomic risk factors were applied. Odds ratios (OR) and adjusted odds ratios (aOR) were calculated to measure the association between CVS and computer use conditions. RESULTS: The prevalence of CVS was 76.6%, and the female gender, age ≤ 20 years, levels I, II, III of course, lack of knowledge about ergonomics, use the computer to study, use more than 6 hours daily, absence of anti-reflex treatment, use of other devices and sitting in an inappropriate chair were risk factors for the occurrence of CVS, while being a teacher was a protective factor. CONCLUSION: The prevalence of CVS found in this study was high, due to several factors, especially not using ergonomic principles when using computers and other DVTs. There is a need to adopt intervention strategies focused on the most vulnerable groups such as women, age group ≤20 years and students, especially at the first year level, right after entering the University.

The Visually Induced Motion Sickness Susceptibility Questionnaire (VIMSSQ): Estimating Individual Susceptibility to Motion Sickness-Like Symptoms When Using Visual Devices.

OBJECTIVE: Two studies were conducted to develop and validate a questionnaire to estimate individual susceptibility to visually induced motion sickness (VIMS). BACKGROUND: VIMS is a common side-effect when watching dynamic visual content from various sources, such as virtual reality, movie theaters, or smartphones. A reliable questionnaire predicting individual susceptibility to VIMS is currently missing. The aim was to fill this gap by introducing the Visually Induced Motion Sickness Susceptibility Questionnaire (VIMSSQ). METHODS: A survey and an experimental study were conducted. Survey: The VIMSSQ investigated the frequency of nausea, headache, dizziness, fatigue, and eyestrain when using different visual devices. Data were collected from a survey of 322 participants for the VIMSSQ and other related phenomena such as migraine. Experimental study: 23 participants were exposed to a VIMS-inducing visual stimulus. Participants filled out the VIMSSQ together with other questionnaires and rated their level of VIMS using the Simulator Sickness Questionnaire (SSQ). RESULTS: Survey: The most prominent symptom when using visual devices was eyestrain, and females reported more VIMS than males. A one-factor solution with good scale reliability was found for the VIMSSQ. Experimental study: Regression analyses suggested that the VIMSSQ can be useful in predicting VIMS (R2 = .34) as measured by the SSQ, particularly when combined with questions pertaining to the tendency to avoid visual displays and experience syncope (R2 = .59). CONCLUSION: We generated normative data for the VIMSSQ and demonstrated its validity. APPLICATION: The VIMSSQ can become a valuable tool to estimate one's susceptibility to VIMS based on self-reports.

Computer Vision Syndrome: An Ophthalmic Pathology of the Modern Era.

Digital device usage has increased significantly in last decade among all age groups, both for educational and recreational purposes. Computer vision syndrome (CVS), also known as digital eye strain (DES), represents a range of ocular, musculoskeletal, and behavioral conditions caused by prolonged use of devices with digital screens. This paper reviews the principal environmental, ocular, and musculoskeletal causes for this condition. Due to the high prevalence of DES and frequent usage of digital devices, it is important that eye care practitioners be able to provide advice and management options based on quality research evidence.

The changes and causes of asthenopia after ICL implantation.

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

Population perceived eye strain due to digital devices usage during COVID-19 pandemic.

PURPOSE: To assess the magnitude severity and determinants of eyestrain and the use of digital devices in a Saudi population during the COVID-19 pandemic lockdown. METHODS: This web-based survey was conducted in September 2020 and enrolled only Saudi nationals 15 years or older. Data were collected on demographics, eye strain related symptoms, severity, and the use of optical aids during the COVID-19 lockdown. The frequency and severity of eye strain were calculated. A Computer Vision Syndrome (CVS) score was graded as none/mild moderate and severe, based on the sum of 15-eye strain related signs and symptoms. Correlation analysis was performed for determinants of CVS. RESULTS: The study sample was comprised of 2009 individuals with median age of 20 years. Among those who used digital devices for more than 6 h daily, the main reasons for use were work and social purposes among 68.4%, and 61% of respondents, respectively. The prevalence of knowledge on CVS and the '20-20 rule for using digital devices' was 9.4% and 6.9, respectively. The most common symptoms of eye strain from digital device usage were headache, burning, itching, tearing, and redness of eyes. Six hours of daily usage of digital devices was positively associated to the grade of eye strain severity during the COVID-19 lockdown (P < 0.05)). CONCLUSION: The Saudi population experienced eye strain during COVID-19 lockdown due to excessive digital devices usage. Longer duration of digital device usage was associated to eye strain. Health care providers should educate the general population on measures to mitigate eye strain due to digital devices. Trial registration ID None applicable.

Computer vision syndrome-related symptoms in presbyopic computer workers.

PURPOSE: To evaluate the prevalence of computer vision syndrome (CVS)-related symptoms in a presbyopic population using the computer as the main work tool, as well as the relationship of CVS with the electronic device use habits and the ergonomic factors. METHODS: A sample of 198 presbyopic participants (aged 45-65 years) who regularly work with a computer completed a customised questionnaire divided into: general demographics, optical correction commonly used and for work, habits of electronic devices use, ergonomic conditions during the working hours and CVS-related symptoms during work performance. A total of 10 CVS-related symptoms were questioned indicating the severity with which they occurred (0-4) and the median total symptom score (MTSS) was calculated as the sum of the symptoms. RESULTS: The MTSS in this presbyopic population is 7 ± 5 symptoms. The most common symptoms reported by participants are dry eyes, tired eyes and difficulties in refocusing. MTSS is higher in women (p < 0.05), in laptop computer users (p < 0.05) and in teleworkers compared to office workers (p < 0.05). Regarding ergonomic conditions, MTSS is higher in participants who do not take breaks while working (p < 0.05), who have an inadequately lighting in the workspace (p < 0.05) and in the participants reporting neck (p < 0.01) or back pain (p < 0.001). CONCLUSION: There is a relationship between CVS-related symptoms, the use of electronic devices and the ergonomic factors, which indicates the importance of adapting workplaces, especially for home-based teleworkers, and following basic visual ergonomics rules.

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, no clinical guidelines exist to help practitioners provide evidence-based advice about CVS treatments, many of which are marketed directly to patients. This systematic review and meta-analysis was designed to help inform best practice for eye care providers. METHODS: Eligible randomized controlled trials (RCTs) were identified in Ovid MEDLINE, Embase, the Cochrane Central Register of Controlled Trials, and trial registries, searched from inception through November 23, 2021. Eligible studies were appraised for risk of bias and were synthesized. The certainty of the body of evidence was judged using the Grading of Recommendations, Assessment, Development, and Evaluation system. Standardized mean differences (SMDs) 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 with single-vision lenses (3 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 (3 RCTs), with evidence judged of low certainty. Relative to placebo, oral berry extract supplementation did not improve visual fatigue (7 RCTs; SMD, -0.27; 95% CI, -0.70 to 0.16; P = 0.22) or dry eye symptoms (4 RCTs; SMD, -0.10; 95% CI, -0.54 to 0.33; P = 0.65). Likewise, berry extract supplementation had no significant effects on critical flicker-fusion frequency (CFF) or accommodative amplitude. Oral omega-3 supplementation for 45 days to 3 months improved dry eye symptoms (2 RCTs; mean difference [MD], -3.36; 95% CI, -3.63 to -3.10 on an 18 unit scale; P < 0.00001) relative to placebo. Oral carotenoid supplementation improved CFF (2 RCTs; MD, 1.55 Hz; 95% CI, 0.42 to 2.67 Hz; P = 0.007) relative to placebo, although the clinical significance of this finding is unclear. DISCUSSION: We did not identify high-certainty evidence supporting the use of any of the therapies analyzed. Low-certainty evidence suggested that oral omega-3 supplementation reduces dry eye symptoms in symptomatic computer users.

Distortion corrected tomographic near-eye displays using light field optimization.

Several multifocal displays have been proposed to provide accurate accommodation cues. However, multifocal displays have an undesirable feature, which is especially emphasized in near-eye displays configuration, that the field of views (FOVs) of the virtual planes change over depth. We demonstrate that this change in FOV causes image distortions, which reduces overall image quality, and depth perception error due to the variation of image sizes according to depths. Here, we introduce a light field optimization technique to compensate for magnification variations among the focal planes. Our approach alleviates image distortions, especially noticeable in the contents with large depth discontinuity, and reconstructs the image size to precise depths, while maintaining a specific tolerance length for the target eye relief. To verify the feasibility of the algorithm, we employ this optimization method for the tomographic near-eye display system to acquire the optimal image and backlight sequences for a volumetric scene. In general, we confirm that the structural similarity index measure of reconstructed images against ground truth increases by 20% when the eye relief is 15 mm, and the accommodation cue is appropriately stimulated at the target depth with our proposed method.

Visual fatigue induced by watching virtual reality device and the effect of anisometropia.

The effect of small anisometropia on visual fatigue when using virtual reality (VR) devices was investigated. Participants (n = 34) visited three times. In the first visit, VR exposure (10 min) was conducted with the full correction of the refractive error of both eyes. Experimental anisometropia was induced by adding a + 1.0 dioptre spherical lens either on the dominant eyes in the second visit or on the non-dominant eyes in the third visit. At each visit, the participants played a predetermined video game using a head-mounted display VR for 10 min. Visual fatigue was assessed before and after playing VR game using the Virtual Reality Symptom Questionnaire (VRSQ) and high-frequency component of accommodative microfluctuation. Results showed that watching VR induced significant increase of VRSQ score, significant decrease in the maximum accommodation power and objective increase in visual fatigue. Experimental anisometropia induction either on the dominant or non-dominant eyes did not aggravate visual fatigue. Practitioner summary: Mild differences in refractive error (up to 1.0 dioptre) between both eyes do not significantly increase ocular fatigue by viewing virtual reality device (10 min). The impact of small anisometropia may be limited in developing a virtual reality device. Abbreviations: VR: virtual reality; VRSQ: virtual reality symptom questionnaire; HMD: head-mounted display; HFC: high-frequency component.

[COMPUTER VISION SYNDROME].

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

A 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.

Articulated Instruments and 3D Visualization: A Synergy? Evaluation of Execution Time, Errors, and Visual Fatigue.

Objective. The introduction of advanced endoscopic systems, such as the Storz Image1S and the Olympus Endoeye, heralds a new era of 3-dimensional (3D) visualization. The aim of this report is to provide a comprehensive overview of the neurophysiology of 3D view, its relevance in videoscopy, and to quantify the benefit of the new 3D technologies for both rigid and articulated instruments. Method. Sixteen medical students without any laparoscopic experience were trained each for a total of 27 hours. Proficiency scores were determined for rigid and articulated instruments under 2D and 3D visualization conditions. Results. A reduction in execution time of 14%, 28%, and 36% was seen for the rigid instruments, the da Vinci, and Steerable instruments, respectively. A reduction in errors of 84%, 92%, and 87% was seen for the rigid instruments, the da Vinci, and Steerable instruments, respectively. Conclusion. 3D visualization greatly augments endoscopic procedures. The advanced endoscopic systems employed in the recent study caused no visual fatigue or discomfort. The benefit of 3D was most distinct with articulated instruments.

[Comparative study on visual fatigue caused by watching liquid crystal display and projection display].

Objective: To explore the effect of different types of visual display terminals (VDT) on visual fatigue. Methods: A total of 68 subjects were enrolled and divided into flat screen group, metal screen group and glass bead screen group. The subjects watched a video in the same environment for 60 minutes. Before and after watching, they were asked to fill in a visual fatigue rating scale and underwent visual function examinations. The blink rate of subjects was recorded during the experiment. Results: After watching the video, for the metal screen, glass bead screen, and flat screen group respectively: (1)The median (interquartile range, IQR) of visual fatigue rating increased significantly (before: 1.0 (1.2), 1.3 (1.6), 0.5 (0.9); after: 2.1 (1.9), 2.1 (1.7), 1.2 (1.0); Z=-4.72, -4.83, -3.75; all P<0.05). (2) The median (IQR) of blink frequency increased significantly (before: 11.5 (10.6), 15.3 (11.9), 7.0 (13.0) times/minute; after: 15.0 (13.0), 17.0 (16.0), 15.0 (12.0) times/minute; Z=-2.64, -2.74, -4.12; all P<0.05). (3) The mean (±standard deviation) of critical flicker fusion frequency (CFF) decreased significantly [before: (35.76±2.98), (35.84±2.79), (35.44±2.21) Hz; after: (35.09±2.78), (34.94±2.67), (34.57±2.33) Hz; t=-2.64, -2.38, -4.12; all P<0.05). (4)The median (IQR) of near point of convergence (NPC) became significantly larger [before: 3.9 (2.6), 4.0 (2.5), 4.3 (2.7) cm; after 5.4 (3.8), 4.8 (2.7), 6.1 (3.9) cm; Z=-3.39, -2.27, -3.36; all P<0.05]. (5)The median of negative relative accommodation (NRA) reduced significantly [before: 2.00 (0.50), 2.00 (0.56), 2.00 (0.25) cm; after 1.75 (0.50), 1.75 (0.25), 1.75 (0.50) cm; Z=-1.98, -2.09, -2.53; all P<0.05]. Meanwhile, no significant changes were found for the positive relative accommodation (PRA), accommodative amplitude, accommodative response, negative relative vergence in all groups after watching the video. The comparisons between the three groups showed that, after watching the video, the participants in the two kinds of projection screen group (the metal and glass bead screen group) had more subjective visual fatigue than those in the flat screen group respectively (Z=-2.09, -2.21; all P<0.05), while there was no significant difference in subjective visual fatigue between the two projection screen groups (P>0.05). In addition, positive fusional vergence recovery point and break point decreased after watching the video in the metal screen and glass bead screen group, respectively (t=4.15, 2.07; all P<0.05). However, no such change was found in the flat screen group. Conclusions: Short-term and long-distance VDT operations have significant effects on visual fatigue, which may be due to the decreased positive convergence ability. VDT operations over projection screens may result in more visual fatigue than LED flat panel display, while the effect of different projection screen types have insignificant influences on visual fatigue. (Chin J Ophthalmol, 2019, 55:595-600).

Optical correction of refractive error for preventing and treating eye symptoms in computer users.

BACKGROUND: Computer users frequently complain about problems with seeing and functioning of the eyes. Asthenopia is a term generally used to describe symptoms related to (prolonged) use of the eyes like ocular fatigue, headache, pain or aching around the eyes, and burning and itchiness of the eyelids. The prevalence of asthenopia during or after work on a computer ranges from 46.3% to 68.5%. Uncorrected or under-corrected refractive error can contribute to the development of asthenopia. A refractive error is an error in the focusing of light by the eye and can lead to reduced visual acuity. There are various possibilities for optical correction of refractive errors including eyeglasses, contact lenses and refractive surgery. OBJECTIVES: To examine the evidence on the effectiveness, safety and applicability of optical correction of refractive error for reducing and preventing eye symptoms in computer users. SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL); PubMed; Embase; Web of Science; and OSH update, all to 20 December 2017. Additionally, we searched trial registries and checked references of included studies. SELECTION CRITERIA: We included randomised controlled trials (RCTs) and quasi-randomised trials of interventions evaluating optical correction for computer workers with refractive error for preventing or treating asthenopia and their effect on health related quality of life. DATA COLLECTION AND ANALYSIS: Two authors independently assessed study eligibility and risk of bias, and extracted data. Where appropriate, we combined studies in a meta-analysis. MAIN RESULTS: We included eight studies with 381 participants. Three were parallel group RCTs, three were cross-over RCTs and two were quasi-randomised cross-over trials. All studies evaluated eyeglasses, there were no studies that evaluated contact lenses or surgery. Seven studies evaluated computer glasses with at least one focal area for the distance of the computer screen with or without additional focal areas in presbyopic persons. Six studies compared computer glasses to other types of glasses; and one study compared them to an ergonomic workplace assessment. The eighth study compared optimal correction of refractive error with the actual spectacle correction in use. Two studies evaluated computer glasses in persons with asthenopia but for the others the glasses were offered to all workers regardless of symptoms. The risk of bias was unclear in five, high in two and low in one study. Asthenopia was measured as eyestrain or a summary score of symptoms but there were no studies on health-related quality of life. Adverse events were measured as headache, nausea or dizziness. Median asthenopia scores at baseline were about 30% of the maximum possible score.Progressive computer glasses versus monofocal glassesOne study found no considerable difference in asthenopia between various progressive computer glasses and monofocal computer glasses after one-year follow-up (mean difference (MD) change scores 0.23, 95% confidence interval (CI) -5.0 to 5.4 on a 100 mm VAS scale, low quality evidence). For headache the results were in favour of progressive glasses.Progressive computer glasses with an intermediate focus in the upper part of the glasses versus other glassesIn two studies progressive computer glasses with intermediate focus led to a small decrease in asthenopia symptoms (SMD -0.49, 95% CI -0.75 to -0.23, low-quality evidence) but not in headache score in the short-term compared to general purpose progressive glasses. There were similar small decreases in dizziness. At medium term follow-up, in one study the effect size was not statistically significant (SMD -0.64, 95% CI -1.40 to 0.12). The study did not assess adverse events.Another study found no considerable difference in asthenopia between progressive computer glasses and monofocal computer glasses after one-year follow-up (MD change scores 1.44, 95% CI -6.95 to 9.83 on a 100 mm VAS scale, very low quality evidence). For headache the results were inconsistent.Progressive computer glasses with far-distance focus in the upper part of the glasses versus other glassesOne study found no considerable difference in number of persons with asthenopia between progressive computer glasses with far-distance focus and bifocal computer glasses after four weeks' follow-up (OR 1.00, 95% CI 0.40 to 2.50, very low quality evidence). The number of persons with headache, nausea and dizziness was also not different between groups.Another study found no considerable difference in asthenopia between progressive computer glasses with far-distance focus and monofocal computer glasses after one-year follow-up (MD change scores -1.79, 95% CI -11.60 to 8.02 on a 100 mm VAS scale, very low quality evidence). The effects on headaches were inconsistent.One study found no difference between progressive far-distance focus computer glasses and trifocal glasses in effect on eyestrain severity (MD -0.50, 95% CI -1.07 to 0.07, very low quality evidence) or on eyestrain frequency (MD -0.75, 95% CI -1.61 to 0.11, very low quality evidence).Progressive computer glasses versus ergonomic assessment with habitual (computer) glassesOne study found that computer glasses optimised for individual needs reduced asthenopia sum score more than an ergonomic assessment and habitual (computer) glasses (MD -8.9, 95% CI -16.47 to -1.33, scale 0 to 140, very low quality evidence) but there was no effect on the frequency of eyestrain (OR 1.08, 95% CI 0.38 to 3.11, very low quality evidence).We rated the quality of the evidence as low or very low due to risk of bias in the included studies, inconsistency in the results and imprecision. AUTHORS' CONCLUSIONS: There is low to very low quality evidence that providing computer users with progressive computer glasses does not lead to a considerable decrease in problems with the eyes or headaches compared to other computer glasses. Progressive computer glasses might be slightly better than progressive glasses for daily use in the short term but not in the intermediate term and there is no data on long-term follow-up. The quality of the evidence is low or very low and therefore we are uncertain about this conclusion. Larger studies with several hundreds of participants are needed with proper randomisation, validated outcome measurement methods, and longer follow-up of at least one year to improve the quality of the evidence.

Short-term effect of a developed warming moist chamber goggle for video display terminal-associated dry eye.

BACKGROUND: Video display terminal (VDT)-associated dry eye (DE) patients are the rising group worldwide, and moisture goggles are the preferable treatment since they are capable of improving tear film stability and DE discomfort. The current study aims to evaluate the short-term efficacy and safety of the developed warming moist chamber goggles (WMCGs) for VDT-associated DE patients. METHODS: In this prospective self-control study, 22 DE patients (22 eyes) working with VDTs over 4 h daily were enrolled and instructed to wear WMCGs for 15 min. Sodium hyaluronate (SH, 0.1%) eyedrops were applied as a control on another day on these same patients, however 4 subjects denied the eyedrop application. The symptomatology visual analog scale (VAS) score, tear meniscus height (TMH), noninvasive tear film break-up time (NI-BUT), tear film lipid layer thickness (LLT), and bulbar conjunctival redness were assessed with Keratograph 5 M at baseline, 5, 30 and 60 min after treatment. The WMCGs wearing comfort was also evaluated. RESULTS: The ocular discomfort evaluated by VAS decreased in the WMCGs group throughout 60 min (P<0.001), better than the control group levels (P ≤ 0.015). TMH, NI-BUT (including the first BUT and average BUT) increased than baseline level accross 60 min in the WMCG group (P ≤ 0.012), while those in the control group only showed temporary improvements in 5 min. LLT also increased obviously after WMCGs wear, while the change in the control group was nearly innoticeable. No adverse responses were detected. CONCLUSIONS: Temporary use of the WMCGs is able to relieve ocular discomfort, and improves tear film stability in DE patients for at least 1 h, making it a promising alternative to other treatments.

Computer vision syndrome and ergonomic practices among undergraduate university students.

AIM: To determine the prevalence of computer vision syndrome (CVS) and ergonomic practices among students in the Faculty of Medical Sciences at The University of the West Indies (UWI), Jamaica. METHOD: A cross-sectional study was done with a self-administered questionnaire. RESULTS: Four hundred and nine students participated; 78% were females. The mean age was 21.6 years. Neck pain (75.1%), eye strain (67%), shoulder pain (65.5%) and eye burn (61.9%) were the most common CVS symptoms. Dry eyes (26.2%), double vision (28.9%) and blurred vision (51.6%) were the least commonly experienced symptoms. Eye burning (P = .001), eye strain (P = .041) and neck pain (P = .023) were significantly related to level of viewing. Moderate eye burning (55.1%) and double vision (56%) occurred in those who used handheld devices (P = .001 and .007, respectively). Moderate blurred vision was reported in 52% who looked down at the device compared with 14.8% who held it at an angle. Severe eye strain occurred in 63% of those who looked down at a device compared with 21% who kept the device at eye level. Shoulder pain was not related to pattern of use. CONCLUSION: Ocular symptoms and neck pain were less likely if the device was held just below eye level. There is a high prevalence of Symptoms of CVS amongst university students which could be reduced, in particular neck pain and eye strain and burning, with improved ergonomic practices.

Feasibility Study of the Three-Dimensional Flexible Endoscope in Endoscopic Submucosal Dissection: An ex vivo Animal Study.

BACKGROUND/AIM: Clinical application of 3-dimensional (3D) technology for flexible endoscopes has not been reported. We developed a 3D flexible endoscope and conducted a feasibility study of endoscopic submucosal dissection (ESD) in porcine stomach. METHODS: Four endoscopists used a 3D flexible endoscope to perform a total of 8 ESD procedures on resected porcine stomachs. We assessed the en bloc resection rate, perforation rate, and mechanical issues that arise during ESD. A visual analog scale (0, 2D superior; 100, 3D superior) was used to evaluate the depth perception, sense of security of the procedure, and eyestrain of 3D visualization. RESULTS: En bloc resection was achieved in all cases and there were no cases of perforation or mechanical issues. Depth perception and sense of security were rated 85.5 ± 12.4 and 70.7 ± 9.7 respectively (mean ± SDs). Eyestrain was rated high for 3D visualization (mean ± SDs, 12.6 ± 8.6). CONCLUSIONS: ESD using a 3D flexible endoscope was technically feasible. The endoscopists reported good depth perception and a high sense of security when using 3D visualization but also noted strong eyestrain.

Risk factors and visual fatigue of baggage X-ray security screeners: a structural equation modelling analysis.

This study identified the risk factors influencing visual fatigue in baggage X-ray security screeners and estimated the strength of correlations between those factors and visual fatigue using structural equation modelling approach. Two hundred and five X-ray security screeners participated in a questionnaire survey. The result showed that satisfaction with the VDT's physical features and the work environment conditions were negatively correlated with the intensity of visual fatigue, whereas job stress and job burnout had direct positive influences. The path coefficient between the image quality of VDT and visual fatigue was not significant. The total effects of job burnout, job stress, the VDT's physical features and the work environment conditions on visual fatigue were 0.471, 0.469, -0.268 and -0.251 respectively. These findings indicated that both extrinsic factors relating to VDT and workplace environment and psychological factors including job burnout and job stress should be considered in the workplace design and work organisation of security screening tasks to reduce screeners' visual fatigue. Practitioner Summary: This study identified the risk factors influencing visual fatigue in baggage X-ray security screeners and estimated the strength of correlations between those factors and visual fatigue. The findings were of great importance to the workplace design and the work organisation of security screening tasks to reduce screeners' visual fatigue.