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Electronic displays, including laptops, tablets, and smartphones, have dramatically altered the way information is accessed and become significant factors in human daily life. They interfere with the blink rate and increase dry eye symptoms, which lead to more discomfort compared to hard copy while reading. Digital eye strain occurs when an individual suffers from symptoms, or they are exacerbated, while performing a task requiring digital screen viewing. This study assessed the tear film status immediately following reading on a laptop computer screen versus an identical hard copy. Thirty young adults with normal ocular health and reporting no significant symptoms of dry eye (ocular surface disease index (OSDI) score < 13 and non-invasive tear break-up time (NITBUT) > 10 seconds) read a text as hard copy and on a laptop computer screen for 30 min on separate days in a random sequence in a controlled reading experimental condition. The texts were matched in size and contrast and presented at a viewing distance of 40 cm. The NITBUT and strip meniscometry tube tests were administered at baseline and after reading in both conditions. The median baseline NITBUT decreased from 13.0 s to 10.0 s (P < 0.001) after hardcopy reading and to 7.0 (P < 0.001) after reading from a laptop computer screen, with a significant difference between the task medium (P = 0.001). The baseline strip meniscometry tube results decreased from 6.7 mm to 5.0 mm (P < 0.001) after hardcopy reading and to 5.0 mm (P < 0.001) after reading from a laptop computer screen, but there was no significant difference with the task medium (P = 0.085). Reading in both conditions led to tear film instability in terms of the tear film quality and quantity. Additionally, the computer screen has a greater impact on the TBUT compared to hardcopy reading, while these two reading mediums had a similar effect on the tear volume. [ABSTRACT FROM AUTHOR]

To determine the prevalence of ophthalmological findings suggesting an ocular cause for headache or occult neurological disease, among children with headache. Retrospective cross-sectional study on children with headache at a tertiary outpatient ophthalmology clinic. All children underwent sensorimotor, anterior segment, and dilated fundoscopic examinations, with or without cycloplegic refraction. Prevalence of one or more new findings of ocular or occult neurological cause of headache, including glaucoma, uveitis, optic nerve elevation, or possible asthenopia from strabismus or refractive issues. Headache characteristics and associated symptoms were evaluated as risk factors for ocular findings. Among 1,878 children with headache (mean age 10 yrs, range 2–18), 492 (26.1%, 95% CI 24.3–28.2%) children had one or more new ocular findings that could cause headache or indicate intracranial disease: refractive issues (342, 18.2%), strabismus (83, 4.4%), optic nerve elevation (51, 2.7%; 26 with papilledema, 25 with pseudopapilledema), uveitis (6, 0.3%), and glaucoma (2, 0.1%). Shorter headache duration was associated with ocular findings (p =.047), but headache frequency, photophobia, nausea/vomiting, and visual changes were not. In univariable analysis, visual changes (p ≤.001), nausea/vomiting (p ≤.002), and morning headache (p =.02) were associated with optic nerve elevation. An ophthalmologic examination including cycloplegic refraction is indicated in children with headache, as one-quarter have a treatable ocular condition, which may be related to the headache, or sign of intracranial pathology. While nausea, visual changes, or morning headache should raise concern, coincident visual, ocular, or systemic symptoms are not reliable predictors of discovering ocular pathology in a child with headache. [ABSTRACT FROM AUTHOR]

Dry eye disease (DED) is a worldwide, multifactorial disease mainly caused by a deficit in tear production or increased tear evaporation with an increase in tear osmolarity and inflammation. This causes discomfort and there is a therapeutic need to restore the homeostasis of the ocular surface. The aim of the present work was to develop a biodegradable and biocompatible liposomal formulation from the synthetic phospholipids 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) that is able to reduce the effects of hypertonic stress by helping to restore the lipid layer of the tear film. Liposomes were made using the lipid film hydration method with synthetic phospholipids (10 mg/mL) with and without 0.2% HPMC. They were characterised in terms of size, osmolarity, pH, surface tension, and viscosity. Additionally, the in vitro toxicity of the formulation at 1 and 4 h in human corneal epithelial cells (hTERT-HCECs) and human conjunctival cells (IM-HConEpiC) was determined. Furthermore, osmoprotective activity was tested in a corneal model of hyperosmolar stress. In vivo acute tolerance testing was also carried out in albino New Zealand rabbits by topical application of the ophthalmic formulations every 30 min for 6 h. All the assayed formulations showed suitable physicochemical characteristics for ocular surface administration. The liposomal formulations were well-tolerated in cell cultures and showed osmoprotective activity in a hyperosmolar model. No alterations or discomfort were reported when they were topically administered in rabbits. According to the results, the osmoprotective liposomal formulations developed in this work are promising candidates for the treatment of DED. [ABSTRACT FROM AUTHOR]

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. 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. 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. 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. 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. [ABSTRACT FROM AUTHOR]

Clinical Relevance: Home-isolation and social distancing during the COVID-19 pandemic caused increased use of digital devices, posing a greater risk of developing digital eye strain-related symptoms. Eye-care professionals should educate patients about limiting screen time and managing digital eye strain symptoms.Background: This study aimed to evaluate the COVID-19 isolation's impact on digital device use by comparing hours spent on digital devices before and during the 24-hour curfew in Saudi Arabia, while assessing the symptoms associated with digital eye strain.Methods: A self-reported questionnaire was used to compare the total hours per day, either continuous or intermittent, spent on digital devices during and before curfew, and the association of these durations with digital eye strain.Results: A total of 1,939 participants, (mean ± SD: 33 ± 12.2 years and 72% women) were recruited. Results showed a significant difference between usage duration before and during curfew. Digital eye strain incidence was 78% during the curfew. Chi-squared analysis indicated most symptoms are associated with usage duration and employment status. Multivariate analysis revealed significant associations between digital eye strain and the following factors: using more than one device (odds ratio 1.208, 95% confidence interval: 1.068-1.3661), age, optical correction, employment status, gender, using rewetting drops, and usage duration.Conclusions: In this population, prolonged use of digital devices significantly increased during home-isolation. Digital eye strain incidence increased during curfew. Regular eye exams should be encouraged to ensure the use of optimum prescription use and meet the specific visual demands required for the use of digital devices. Eye-health strategies and awareness campaigns should be employed on the importance of regular eye exams, decreasing screen time, practising the 20-20-20 rule, and the use of rewetting drops to help reduce the symptoms of digital eye strain during this period. [ABSTRACT FROM AUTHOR]

Extra time of sitting in front of a digital device is required for e-learning by children during Corona virus (COVID-19) pandemic which can lead to many ocular problems including digital eye strain (DES). In view of increased incidence of DES in children, multiple studies had been conducted in central India to assess the eye strain in children due to excessive online classes as a research project named "Digital eye strain among kids (DESK) study." This study DESK-3 aimed to report series of cases of acute acquired comitant esotropia (AACE) in children attending online classes during COVID-19 pandemic. Children aged 6–18 years with recent onset of esotropia of < 1-month duration without any similar history in past presented in month of July-August 2020 at a tertiary children eye care hospital were evaluated. Data collection included age and gender of child, presence or absence of diplopia, visual acuity, duration of smartphone use, duration of online classes, angle of deviation for near and distance and cycloplegic refraction. Total eight children of AACE were included in the study. The mean age of children was 12.5 ± 4.2 years. All eight were males. The mean duration of smartphone use was 4.6 + 0.7 hours per day. All children were attending online classes > 4 hours per day on smartphone of average size 5.5 inches. Five children were emmetropic, one myopic, one pseudomyopic and one hyperopic. The angle of deviation for near and distance were 48.1 ± 16.4 PD and 49.3 ± 15.9 PD respectively with normal ocular motility. Seven children complained of horizontal diplopia in all gazes. Neurological examination and CT scan of brain and orbit was normal in all patients. Two months before the lockdown only one case was identified as compared to eight during the lockdown. Prolonged near work during smart phone use for e-learning might lead to the development of AACE in children. [ABSTRACT FROM AUTHOR]

Background: Blue blocking (BB) lenses, including spectacles and intraocular lenses, work by attenuating short-wavelength light. BB glasses are being marketed with the aim to reduce eye fatigue symptoms when using digital devices, improve sleep quality and potentially confer protection from retinal phototoxicity. BB intraocular lenses following cataract surgery may be implanted because they are thought to prevent age-related macular degeneration (AMD) progression. Methods: The present study is a systematic review aiming to analyze BB lenses clinical efficacy in preventing blue light-related ocular disorders, including AMD progression, eye fatigue, and their impact on sleep quality. We searched Medline, PubMed, Web of Science and the Cochrane Library until May 2020. Results:Although several studies have been performed investigating BB lenses, clinical efficacy for preventing or attenuating the above-mentioned ocular disorders is often theorical or based on laboratory or animal experiments. Conclusions: To date, there is a lack of consistent evidence for a larger-sclale introduction of BB lenses in the routine clinical practice. [ABSTRACT FROM AUTHOR]

Purpose: There has been an enormous increase in the use of gadgets for online classes and entertainment during the COVID-19 pandemic. This study aimed to estimate the prevalence of digital eye strain (DES), describe the pattern of gadget usage, and analyse the risk factors for DES. Methods: This online survey analysed 941 responses from students of online classes (688), teachers of online classes (45), and general population (208). A pre-validated questionnaire was used to calculate the DES score. Non-parametric tests of medians were used to compare the median DES score, Chi-square test to compare categorical variables, and binary logistic regression to find the predictors of DES. Results: The prevalence of eye strain was higher among students taking online classes compared to the general public (50.6% vs 33.2%; χ2 = 22.5, df = 1, p <.0001). There was an increase in screen time during the pandemic compared to pre-pandemic time. The DES score was highest among students attending online classes (p <.0001), in those with eye diseases (p =.001), greater screen time (p = <0.0001), screen distance <20 cm (p =.002), those who used gadgets in dark (p =.017) and those who took infrequent/no breaks (p =.018). The DES scores were proportional to the increase in the number of hours of gadget usage during the pandemic. Conclusion: There is a need to educate people about limiting overall screen exposure and ergonomic methods of screen viewing. Efforts from policymakers to reduce the duration of online classes for students and online work hours for professionals are warranted to control this epidemic of eye strain. [ABSTRACT FROM AUTHOR]

In virtual reality (VR), users can experience symptoms of motion sickness, which is referred to as VR sickness or cybersickness. The symptoms include but are not limited to eye fatigue, disorientation, and nausea, which can impair the VR experience of users. Though many studies have attempted to reduce the discomfort, they produced conflicting results with varying degrees of VR sickness. In particular, a visually improved VR does not necessarily result in decreased VR sickness. To understand these unexpected results, we surveyed the causes of VR sickness and measurement of symptoms. We reorganized the causes of the VR sickness into three major factors (hardware, content, and human factors) and investigated the sub-component of each factor. We then surveyed frequently used measures of VR sickness, both subjective and objective approaches. We also investigated emerging approaches for reducing VR sickness and proposed a multimodal fidelity hypothesis to give an insight into future studies. [ABSTRACT FROM AUTHOR]

E-learning offers many advantages like being economical, flexible and customizable, but also has challenging aspects such as lack of – social-interaction, which results in contemplation and sense of remoteness. To overcome these and sustain learners' motivation, various stimuli can be incorporated. Nevertheless, such adjustments initially require an assessment of engagement level. In this respect, we propose estimating engagement level from facial landmarks exploiting the facts that (i) perceptual decoupling is promoted by blinking during mentally demanding tasks; (ii) eye strain increases blinking rate, which also scales with task disengagement; (iii) eye aspect ratio is in close connection with attentional state and (iv) users' head position is correlated with their level of involvement. Building empirical models of these actions, we devise a probabilistic estimation framework. Our results indicate that high and low levels of engagement are identified with considerable accuracy, whereas medium levels are inherently more challenging, which is also confirmed by inter-rater agreement of expert coders. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this paper, a unique approach is proposed to determine eye strain in children caused due to the prolonged exposure to LCD and PDP screens. Blink rate and area of eye sclera are the two efficient metrics relied upon to determine eye strain. Initially, blink rate is computed by monitoring state transitions from open to closed eyes. To segment the sclera region of the eye Otsu's thresholding and colour tracking, were implemented. These approaches had limitations due to illumination and skin tone. To overcome this, Modified Otsu using Colour Tracking is proposed in this paper. The occurrence of eye strain is determined by comparing the values of the metrics derived in real time with a threshold. The proposed algorithm detects eye strain with an accuracy of 83%. After detection of fatigue an alert message is sent to caretakers. [ABSTRACT FROM AUTHOR]

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 (~1.5Δ 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. [ABSTRACT FROM AUTHOR]

Purpose: Epidemiological evidence regarding the radiosensitivity of the lens of the eye and radiation cataract development has led to changes in the EU Basic Safety Standards for protection of the lens against ionizing radiation. However, mechanistic details of lens radiation response pathways and their significance for cataractogenesis remain unclear. Radiation-induced DNA damage and the potential impairment of repair pathways within the lens epithelium, a cell monolayer that covers the anterior hemisphere of the lens, are likely to be involved. Materials and Methods: In this work, the lens epithelium has been analyzed for its DNA double-strand break (DSB) repair response to ionizing radiation. The responses of epithelial cells located at the anterior pole (central region) have been compared to at the very periphery of the monolayer (germinative and transitional zones). Described here are the different responses in the two regions and across four strains (C57BL/6, 129S2, BALB/c and CBA/Ca) over a low dose (0-25 mGy) in-vivo whole body X-irradiation range up to 24 hours post exposure. Results: DNA damage and repair as visualized through 53BP1 staining was present across the lens epithelium, although repair kinetics appeared non-uniform. Epithelial cells in the central region have significantly more 53BP1 foci. The sensitivities of different mouse strains have also been compared. Conclusions: 129S2 and BALB/c showed higher levels of DNA damage, with BALB/c showing significantly less inter-individual variability and appearing to be a more robust model for future DNA damage and repair studies. As a result of this study, BALB/c was identified as a suitable radiosensitive lens strain to detect and quantify early low dose ionizing radiation DNA damage effects in the mouse eye lens specifically, as an indicator of cataract formation. [ABSTRACT FROM AUTHOR]

End-of-day (EOD) symptoms of dryness are too often the cause of poor soft contact lens (SCL) tolerance and abandonment of wear. This review examines an amplifying cascade model for these symptoms, which involve thin tear layers on contact lens (CL) front surfaces being susceptible to evaporation-related short tear breakup (TBU) times. Susceptibility to faster tear loss by evaporation may be exacerbated by other forms of tear instability, such as lipid and mucin deficiencies as well as lens surface soiling. Bulbar and palpebral conjunctival hyperaemia and associated faster evaporation of warmer pre-conjunctival tears could also contribute to evaporative dry eye EOD symptoms. In CL wearers, a cascade of increasing hyperaemia toward the end of day, associated increasing tear temperature and evaporative loss, shortened TBU times (TBUTs) and increased osmolarity, all elevate the risk of higher symptom levels according to progressive amplification of this cascade. Chronic wound healing responses to SCL wear, perhaps related to limbal conjunctival trauma, stem cell deficiency and persistent epitheliopathy, as well as one or more immune responses, may contribute directly or indirectly to inflammation and the amplifying evaporative dryness cascade. A diurnal cycle that culminates in EOD symptoms appears to involve a process of recovery from causal mechanisms after lens removal, which allows lenses to be worn comfortably, at least initially the next day. Possible recovery processes are discussed in this review as are procedures that may help de-amplify an inflammatory, evaporative dryness cascade and alleviate EOD symptoms. Evidence of an accrual of adverse responses over long periods of more or less successful lens wear indicate an incremental failure to recover from EOD hyperaemia. Such incremental failure could help explain how SCL wear too often needs to be abandoned after many years of comfortable wear. [ABSTRACT FROM AUTHOR]

This paper presents a nonintrusive prototype computer vision system for real-time fatigue driving detection. First, we use Haar-like features to detect a driver’s face and conduct tracking by introducing an improved Camshift algorithm. Second, we propose a new eye-detection algorithm that combines the Adaboost algorithm with template matching to reduce computational costs and add an eye-validation process to increase the accuracy of the detection rate. Third, and different from other methods focusing on detecting eyes using the ‘bright pupil’ effect, which only works well only for certain constrained lighting conditions, our method detects and estimates the iris center in the hue (H) channel of the hue, saturation, value color space and fits the iris with an ellipse. After extracting the eye fatigue features, we calculate the PERCLOS measurement for fatigue evaluation. This system has been tested on the IMM Face Database, which contains more than 200 faces, and in a real-time test. The experimental results show that the system possesses good accuracy and robustness. [ABSTRACT FROM AUTHOR]

Purpose: This study was conducted to investigate the asthenopic symptoms in patients with exotropia and esotropia while watching stereoscopic 3D (S3D) television (TV). Methods: A total 77 subjects who more than 9 years of age were enrolled in this study. We divided them into three groups; Thirty-four patients with exodeviation (Exo group), 11 patients with esodeviation (Eso group) and 32 volunteers with normal binocular vision (control group). The S3D images were shown to all patients with S3D high-definition TV for a period of 20 min. Best corrected visual acuity, refractive errors, angle of strabismus, stereopsis test and history of strabismus surgery, were evaluated. After watching S3D TV for 20 min, a survey of subjective symptoms was conducted with a questionnaire to evaluate the degree of S3D perception and asthenopic symptoms such as headache, dizziness and ocular fatigue while watching 3D TV. Results: The mean amounts of deviation in the Exo group and Eso group were 11.2 PD and 7.73PD, respectively. Mean stereoacuity was 102.7 arc sec in the the Exo group and 1389.1 arc sec in the Eso group. In the control group, it was 41.9 arc sec. Twenty-nine patients in the Exo group showed excellent stereopsis (≤60 arc sec at near), but all 11 subjects of the Eso group showed 140 arc sec or worse and showed more decreased 3D perception than the Exo and the control group ( p < 0.001, Kruskal-Wallis test). The Exo group reported more eye fatigue ( p < 0.001, Kruskal-Wallis test) than the Eso and the control group. However, the scores of ocular fatigue in the patients who had undergone corrective surgery were less than in the patients who had not in the Exo group ( p < 0.001, Kruskal-Wallis test) and the amount of exodeviation was not correlated with the asthenopic symptoms (dizziness, r = 0.034, p = 0.33; headache, r = 0.320, p = 0.119; eye fatigue, r = 0.135, p = 0.519, Spearman rank correlation test, respectively). Conclusion: Symptoms of 3D asthenopia were related to the presence of exodeviation but not to esodeviation. This may indicate that S3D symptoms are closely related to the convergence demand. [ABSTRACT FROM AUTHOR]

Visual stress is a condition characterised by symptoms of eyestrain, headaches and distortions of visual perception when reading text. The symptoms are frequently alleviated with spectral filters and precision tinted ophthalmic lenses. Visual stress is thought to arise due to cortical hyperexcitability and is associated with a range of neurological conditions. Cortical hyperexcitability is known to occur following stroke. The case presented describes visual stress symptoms resulting from stroke, subsequently managed with spectral filters and precision tinted ophthalmic lenses. The case also highlights that the spectral properties of the tint may need to be modified if the disease course alters. [ABSTRACT FROM AUTHOR]

Purpose: To understand the mechanisms of action of cyclosporin A eye drops in severe allergic diseases such as vernal keratoconjunctivitis, the inhibitory effects of cyclosporin A eye drops on fibrosis and inflammatory cell infiltration in murine allergic conjunctivitis were evaluated. Methods: BALB/c mice that had been actively sensitized with ovalbumin were challenged with ovalbumin on days 10-14 after initial sensitization. Cyclosporin A (0.1%) or betamethasone (0.1%) eye drops were instilled 1, 4, and 7 hours after each challenge. Ocular tissue was harvested for histological evaluation 24 hours after the last challenge, and conjunctival tissue was collected for the measurement of collagen content and quantitative PCR 8 hours after the last challenge. Results: Scores for fibrosis and inflammatory cell infiltration and collagen content in the conjunctiva were higher after 5 days of antigen challenge than in normal non-challenged conjunctiva. Instillation of cyclosporin A or betamethasone reduced the antigen-induced increases in scores for fibrosis and inflammatory cell infiltration in the conjunctiva, and cyclosporin A significantly reduced the antigen-induced increase in conjunctival collagen content. Betamethasone also showed a tendency to reduce the increase in collagen content. Cyclosporin A and betamethasone decreased the numbers of CD3+ and CD4+ T-cells and eosinophils in the conjunctiva, but did not affect the number of mast cells. Neither type of eye drop suppressed the increase in vascular permeability that occurred for 30 minutes after the last antigen challenge. In quantitative PCR, cyclosporin A suppressed the expression of IL-4 and IL-5 mRNA but did not suppress the expression of transforming growth factor (TGF)-β 1, whereas betamethasone suppressed the expression of IL-4, IL-5, and TGF-β 1. Conclusion: The results suggest that cyclosporin A eye drops inhibited fibrosis and inflammatory cell infiltration by the suppression of Th2 cytokine production in repeatedly antigen-challenged conjunctiva without affecting the early-phase reaction. [ABSTRACT FROM AUTHOR]

Objective: This report describes the design and methodology of the Convergence Insufficiency Treatment Trial (CITT), the first large-scale, placebo-controlled, randomized clinical trial evaluating treatments for convergence insufficiency (CI) in children. We also report the clinical and demographic characteristics of patients. Methods: We prospectively randomized children 9 to 17 years of age to one of four treatment groups: 1) home-based pencil push-ups, 2) home-based computer vergence/accommodative therapy and pencil push-ups, 3) office-based vergence/accommodative therapy with home reinforcement, 4) office-based placebo therapy. Outcome data on the Convergence Insufficiency Symptom Survey (CISS) score (primary outcome), near point of convergence (NPC), and positive fusional vergence were collected after 12 weeks of active treatment and again at 6 and 12 months posttreatment. Results: The CITT enrolled 221 children with symptomatic CI with a mean age of 12.0 years (SD = +2.3). The clinical profile of the cohort at baseline was 9Δ exophoria at near (+/- 4.4) and 2Δ exophoria (+/-2.8) at distance, CISS score = 30 (+/-9.0), NPC = 14 cm (+/- 7.5), and near positive fusional vergence break = 13 Δ (+/- 4.6). There were no statistically significant nor clinically relevant differences between treatment groups with respect to baseline characteristics (p > 0.05).Conclusion: Hallmark features of the study design include formal definitions of conditions and outcomes, standardized diagnostic and treatment protocols, a placebo treatment arm, masked outcome examinations, and the CISS score outcome measure. The baseline data reported herein define the clinical profile of those enrolled into the CITT. [ABSTRACT FROM AUTHOR]

Eyestrain, or asthenopia, can be categorized into 2 types: an internal type consisting of sensations of strain and ache felt inside the eye and caused by stress of the accommodative and convergence mechanisms; and an external type consisting of sensations of dryness and irritation on the front of the eye and caused by compromised conditions in the viewing environment. The symptom sensations of the external type mimic those expected due to dry eyes. The likely mechanism is that poor viewing conditions cause contraction of the orbital portion of the orbicularis oculi muscle which causes eye lid squint in an attempt to improve vision. This has been shown to result in secondary reduction in eye lid blink, thereby resulting in dry eye conditions. Electromyography is a sensitive measure of contraction of the orbicularis and has potential to be an objective measure of eyestrain. [ABSTRACT FROM AUTHOR]

The study described in this article was designed to evaluate visual fatigue induced during video display terminal (VDT) tasks. Newly developed equipment was used that can simultaneously measure pupillary change, focal accommodation, and eye movement. The changes in these 3 physiological measures, taken during a VDT task, were used to propose an index for evaluating visual fatigue. Through multiple regression analysis, an index to describe the psychological sense of visual fatigue was obtained. In this index, the minimum pupil diameter, velocity of focal accommodation for constriction, and width of focal accommodation were included. The results suggest that visual fatigue in VDT tasks can be evaluated effectively using both pupil diameter and focal accommodation. The index can be used to assess visual fatigue induced during a VDT task if the following 3 conditions are satisfied: 1. Head movement is limited and infrequent. 2. The task requires focal accommodation. 3. During the task, there is no outstanding change in the lighting environment such as luminous intensity or brightness. [ABSTRACT FROM AUTHOR]

SUMMARY In two experiments, with a total of 116 male and female undergraduate Ss, predictions were tested from the following hypothesized explanation of autokinetic movement (AKM): undetected eye drifts lead to movement of the AKM target across the retina; this movement or error signal leads to the initiation of a cancelling response, and the AKM is directly due to CNS monitoring of the efferent responses or signals sent to the eye muscles with subsequent detection of these signals against a background of efferent noise. The error signal variables studied were stimulus color (yellow or blue-green), stimulus intensity (dim or bright), and stimulus size (1.0 or .1 deg visual angle). Small, dim lights foveally viewed and yellow as opposed to blue-green lights led to significantly more error signals and hence more AKM as measured by mean number of perceived direction changes. Also, increasing retinal displacement by changing viewing angle (from zero to 60 deg) or increasing displacement by increasing diopter strength of prisms (from zero to 30) decreased AKM as measured by number of direction changes, and this effect is due at least in part to the increase in efferent noise caused by the increases in eye muscle tension involved. It was concluded that retinal displacement affects both error signal and noise variables in the AKM and, presumably, in the perception of real movement as well. [ABSTRACT FROM AUTHOR]

SUMMARY Autokinetic movement (AKM) as assessed by number of reported direction changes was evaluated for 25 college sophomores as a function of prism displacement strength. The results indicated that the strain on the eye muscles produced by prism displacement significantly affected frequency of direction change reports: the greater the displacement, the fewer the number of reported direction changes. These results were interpreted according to outflow theory in terms of the prism-imposed strain effectively increasing the level of noise in the outflow monitoring system, thereby making the detection of a cancelling response signal, the direction change, more difficult. [ABSTRACT FROM AUTHOR]

Background: This paper investigates viewing distances and eyestrain symptoms in young adults reading from a smartphone for 60 minutes.Methods: A survey related to common asthenopic (eyestrain) symptoms was administered to subjects before and after they read an extract from a novel on a smartphone for 60 minutes. Subjects rated their symptoms on a scale from zero (not at all) to four (extremely). The viewing distance to the smartphone was measured on a photograph taken of the subject every minute. Each subject used the same smartphone and read the same text.Results: Subjects were 18 young adults (mean age: 21.5 ± 3.3 years) with self-reported good health, normal visual acuity and no accommodative or binocular vision disorders. The mean viewing distance while using a smartphone over 60 minutes was 29.2 ± 7.3 cm. The viewing distance was significantly greater during the first, second and fifth 10-minute time periods (30.6 ± 7.2 cm, 29.7 ± 7.3 cm and 28.9 ± 8.5 cm, respectively) than during the final 10-minute time period (27.8 ± 7.7 cm) (Wilcoxon, p = 0.023, 0.02 and 0.04, respectively). The total symptom score was significantly greater post-experiment (score = 8.06) than pre-experiment (score = 3.56) (Wilcoxon, p < 0.001). Symptoms of tired eyes, uncomfortable eyes and blur increased significantly after 60 minutes of smartphone use (Wilcoxon, p < 0.05). There was a significant correlation between change in total symptom score and change in viewing distance (ρ = -0.51; p = 0.03). The only single symptom that correlated with a change in viewing distance was 'uncomfortable eyes' (ρ = -0.52, p = 0.03).Conclusion: Viewing distances are closer and eyestrain symptoms are greater after reading from a smartphone for 60 minutes. The viewing distances measured were closer than those previously reported in the literature. [ABSTRACT FROM AUTHOR]