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Introduction Symptoms experienced when using digital devices are known as digital eyestrain (DES) or computer vision syndrome. They can be categorised as either external (associated with dry eye) or internal (related to refractive, accommodative or binocular vision anomalies). In a large cohort of adults with DES, we investigate the prevalence of binocular and accommodative anomalies, contrasting different diagnostic approaches, to evaluate potential mechanisms for the benefit from +0.75D addition lens that has been previously reported. Methods Participants (20−40y) were selected using the Computer Vision Syndrome Questionnaire (CVS-Q) tool as suffering with DES. A comprehensive eye examination was given to each participant, and this paper concentrates on “internal factors”, detected with a refraction and comprehensive testing of binocular and accommodative functions. The effects of low-powered addition lenses (+0.50D, +0.75D, +1.25D; and plano controls) were assessed by double-masked testing with the Wilkins Rate of Reading Test (WRRT) and by subjective preference. Results As previously reported, most participants showed a subjective preference for one of the three convex lenses we used, with +0.75D chosen most frequently. Performance at the WRRT was significantly improved with +0.50D and +0.75D, but not +1.25D. Using a variety of diagnostic criteria, there were no strong associations between WRRT results or CVS-Q scores and any binocular or accommodation functions. The one finding of significance is that a disproportionate number of participants who benefited from adds had an eso-fixation disparity on the near Mallett unit, although this only affected 5% of the population. Conclusions DES is a collection of diverse symptoms that have a multifactorial aetiology. In the sample described here, binocular and accommodative anomalies do not seem to be a major cause of DES. Nevertheless, in view of the multifactorial aetiology it is recommended that patients with the symptoms of DES are assessed with a comprehensive eye examination. Patients with an esophoric fixation disparity on the near Mallett unit are particularly likely to benefit from near additions.

Purpose To investigate if blue-blocking lenses are effective in reducing the ocular signs and symptoms of eye strain associated with computer use. Design Double-masked, randomized controlled trial. Methods A total of 120 symptomatic computer users were randomly assigned (1:1) into a “positive” or “negative” advocacy arm (ie, a clinician either advocating or not advocating for the intervention via a prerecorded video). Participants were further sub-randomized (1:1) to receive either clear (placebo) or blue-blocking spectacles. All participants were led to believe they had received an active intervention. Participants performed a 2-hour computer task while wearing their assigned spectacle intervention. The prespecified primary outcome measures were the mean change (post- minus pre-computer task) in eye strain symptom score and critical flicker-fusion frequency (CFF, an objective measure of eye strain). The study also investigated whether clinician advocacy of the intervention (in a positive or negative light) modulated clinical outcomes. Results All participants completed the study. In the primary analysis, for CFF, no significant effect was found for advocacy type (positive or negative, p = .164) and spectacle intervention type (blue-blocking or clear lens, p = .304). Likewise, for eye strain symptom score, no differences were found for advocacy (p = .410) or spectacle lens types (p = .394). No adverse events were documented. Conclusions Blue-blocking lenses did not alter signs or symptoms of eye strain with computer use relative to standard clear lenses. Clinician advocacy type had no bearing on clinical outcomes.

Objectives Advances in dental operative microscopes (DOMs) enable examination of root canal morphology or detection of root fractures otherwise not visible to the naked eye. However, dental therapy involving prolonged use of DOMs requires precision within a limited visual field, resulting in eye strain among users. This study examined the effects of halogen and light-emitting diode (LED) light sources on asthenopia and visual function following use of DOMs. Methods The study used halogen and LED light sources in DOMs. The first experiment was conducted on 6 participants with corrected visual acuity without any organic eye disease. General visual function test (calculation ability test, hand grip strength test, and ophthalmic examination) and subjective symptom questionnaire were used to evaluate the degree of fatigue before and after DOM use. The second experiment was conducted on 9 participants with spherical equivalents within ±4 diopters (D) and astigmatism of 1 D or less. Accommodative function tests (precise test for asthenopia) and a subjective symptom questionnaire (asthenopia) were used before and after use of DOM. Results No significant changes were noted in the degree of fatigue and ophthalmological parameters before and after the procedure with either light source or in between light sources. The tear firm breakup time was shortened after therapy, and a tendency toward dry eyes was observed while using the LED light source. Conclusions The halogen and LED light sources used for DOM therapy had similar effects on asthenopia of the operators, with no significant changes in visual function.

A widely used paradigm for Brain-Computer Interfaces (BCI) is based on detecting P300 Event-Related Potentials (ERPs) in response to stimulation and concentration tasks. An open challenge corresponds to maximizing the performance of a BCI by considering artifacts arising from the user's cognitive and physical conditions during task execution.In this study, an analysis of the performance of a visual BCI-P300 system was performed under the metrics of Sensitivity (Sen), Specificity (Spe), Accuracy (Acc), and Area-Under the ROC Curve (AUC), considering the main reported factors affecting the neurophysiological behavior of the P300 signal: Concentration Level, Eye Fatigue, and Coffee Consumption.We compared the performance of three P300 signal detection methods (MA-LDA, CCA-RLR, and MA+CCA-RLR) using a public database (GigaScience) in different groups. Data were segmented according to three factors of interest: high and low levels of concentration, high and low eye fatigue, and coffee consumption at different times.The results showed a significant improvement between 3% and 6% for the metrics evaluated for identifying the P300 signal in relation to concentration levels and coffee consumption.P300 signal can be influenced by physical and mental factors during the execution of ERPs evocation tasks, which could be controlled to maximize the interface's capacity to detect the individual's intention.

Advanced manufacturing has resulted in significant changes on the shop-floor, influencing work demands and the working environment. The corresponding safety-related effects, including fatigue, have not been captured on an industry-wide scale. This paper presents results of a survey of U.S. manufacturing workers for the: prevalence of fatigue, its root causes and significant factors, and adopted individual fatigue coping methods. The responses from 451 manufacturing employees were analyzed using descriptive data analysis, bivariate analysis and Market Basket Analysis. 57.9% of respondents indicated that they were somewhat fatigued during the past week. They reported the ankles/feet, lower back and eyes were frequently affected body parts and a lack of sleep, work stress and shift schedule were top selected root causes for fatigue. In order to respond to fatigue when it is present, respondents reported coping by drinking caffeinated drinks, stretching/doing exercises and talking with coworkers. Frequent combinations of fatigue causes and individual coping methods were identified. These results may inform the design of fatigue monitoring and mitigation strategies and future research related to fatigue development.

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.

The use of virtual reality (VR) is associated with several adverse effects including dizziness, headache, and motion sickness. This study investigates how full-immersion VR games cause changes in static balance with associated adverse effects, and whether a fixed or a changing game background is more likely to contribute to such problems. Static balance and adverse effects (eye fatigue and dizziness) were measured in 15 healthy adults under three conditions: baseline; after a full-immersion virtual reality game (PlayStation 4 Pro and PlayStation® VR headset) with a fixed background (15 min); and after a full-immersion virtual reality game with a unfixed background (15 min). Static balance was measured with an AMTI force plate, while eye fatigue and dizziness were measured with the Virtual Reality Symptom Questionnaire (VRSQ) and the Simulator Sickness Questionnaire (SSQ). It was determined that playing a full-immersion VR game had a negative effect on static balance and produced several adverse effects including eye fatigue and dizziness. Moreover, sway velocity and sway length increased significantly in the game with a moving background compared to both the baseline and the game with a fixed background (p < 0.05); VRSQ and SSQ were also significantly higher in this case. It is thus preferable from the perspective of reducing adverse effects that only fixed-background full-immersion VR games be used in rehabilitative interventions.

To evaluate the efficacy of a home-based computer orthoptic program for symptomatic convergence insufficiency (CI) in children.The medical records of participants aged 5 to18 years who were diagnosed with symptomatic CI and were treated with the Computerized Vergence System (CVS) program were retrospectively reviewed. All participants were prescribed 9 or 15 minutes of daily convergence exercises with the CVS program, 5 days per week, for the initial 6 weeks. Near point of convergence (NPC) and near convergence amplitude (NCA) were measured at baseline, 6 week, and final examinations. The presence or absence of diplopia and asthenopia with reading were recorded at baseline and final examinations.A total of 186 participants were included. At diagnosis, 72 participants (39%) reported diplopia and 182 (98%), reported asthenopia. At final examination, 172 participants (92%) were asymptomatic. Twelve participants (6%) subsequently received other treatment modalities. Mean NPC at baseline (5.9 cm) improved after 6 weeks of CVS therapy (3.3 cm) and at final examination (2.9 cm; P0.0005). Mean NCA at baseline (20.3(Δ)) improved after 6 weeks of CVS therapy (37.0(Δ)) and at the final examination (38.0(Δ); P0.0005).In this study, home-based CVS therapy reduced symptoms related to CI and improved the NPC and NCA of most children aged 5 to18 years with symptomatic CI.

Objectives: To design and validate a questionnaire to measure visual symptoms related to exposure to computers in the workplace. Study Design and Setting: Our computer vision syndrome questionnaire (CVS-Q) was based on a literature review and validated through discussion with experts and performance of a pretest, pilot test, and retest. Content validity was evaluated by occupational health, optometry, and ophthalmology experts. Rasch analysis was used in the psychometric evaluation of the questionnaire. Criterion validity was determined by calculating the sensitivity and specificity, receiver operator characteristic curve, and cutoff point. Testeretest repeatability was tested using the intraclass correlation coefficient (ICC) and concordance by Cohen’s kappa (k). Results: The CVS-Q was developed with wide consensus among experts and was well accepted by the target group. It assesses the frequency and intensity of 16 symptoms using a single rating scale (symptom severity) that fits the Rasch rating scale model well. The questionnaire has sensitivity and specificity over 70% and achieved good testeretest repeatability both for the scores obtained [ICC 5 0.802; 95% confidence interval (CI): 0.673, 0.884] and CVS classification (k 5 0.612; 95% CI: 0.384, 0.839). Conclusion: The CVS-Q has acceptable psychometric properties, making it a valid and reliable tool to control the visual health of computer workers, and can potentially be used in clinical trials and outcome research. This study was supported by the Spanish National Institute for Occupational Safety and Health (INSHT) (Grant number: 07/606). Project reference: UAL/PVDVIS.

High quality flat panel computer displays (FPDs) with high resolution screens are now commonplace, and black, grey, white, beige and silver surrounds ('bezels'), matt or glossy, are in widespread use. It has been suggested that bezels with high reflectance, or with a high gloss, could cause eyestrain, and we have investigated this issue. Twenty office workers (unaware of the study purpose) used six different FPDs, for a week each, at their own desk. These displays were identical apart from the bezel colour (black, white or silver) and shininess (matt or glossy). Participants completed questionnaires about their visual comfort at the end of each week, and were fully debriefed in lunch-time focus groups at the end of the study. For the white and the silver bezels, the glossiness of the bezel was not an issue of concern. The participants were significantly less content with the glossy black surround than with the matt black surround, and in general the glossy black bezel was the least-liked of all those used. With the possible exception of this surround, there was no evidence of significantly increased visual discomfort, indicative of eyestrain, as a result of high or low bezel reflectance, or of high glossiness.

Objective To report outcomes of single-stage surgery under topical anaesthesia for the treatment of small-angle strabismus. Design Case series. Participants Thirteen patients, 7 males and 6 females, with a median age of 32 years (range, 20–59 years) were included. Methods Patients with symptomatic small-angle strabismus with stable deviations of no more than 20 prism diopters (PD) in horizontal and 10 PD in vertical were consecutively recruited from the Eye and ENT Hospital of Fudan University between January 2010 and April 2012. Single-stage surgery was performed under topical anaesthesia. Outcome measures were PD, Amblyopia and Strabismus Questionnaire (ASQE) scores, and subjective reduction of symptoms. Results The median duration of symptoms was 40 months (range, 6–96 months). Nine patients had horizontal deviations, 3 had vertical deviations, and 1 had an exodeviation combined with a vertical deviation. All surgeries were completed without complications, and no patients experienced significant discomfort. All patients reported elimination of symptoms on postoperative day 1. Two patients required a second procedure at 1 week because of a return of symptoms. At 6-month follow-up, no patient reported recurrence of symptoms. The overall ASQE score improved from 70 preoperatively to 96 postoperatively ( p = 0.001). Conclusions These results suggest single-stage surgery under topical anaesthesia is an effective treatment for small-angle strabismus. A large, randomized, prospective study to confirm these findings is warranted.

Vergence-accommodation conflict (VAC) is the main contributor to visual fatigue during immersion in virtual environments. Many studies have investigated the effects of VAC using 3D displays and expensive complex apparatus and setup to create natural and conflicting viewing conditions. However, a limited number of studies targeted virtual environments simulated using modern consumer-grade VR headsets. Our main objective, in this work, is to test how the modern VR headsets (VR simulated depth) could affect our vergence system, in addition to investigating the effect of the simulated depth on the eye-gaze performance. The virtual scenario used included a common virtual object (a cube) in a simple virtual environment with no constraints placed on the head and neck movement of the subjects. We used ocular biomechanics and eye tracking to compare between vergence angles in matching (ideal) and conflicting (real) viewing conditions. Real vergence angle during immersion was significantly higher than ideal vergence angle and exhibited higher variability which leads to incorrect depth cues that affects depth perception and also leads to visual fatigue for prolonged virtual experiences. Additionally, we found that as the simulated depth increases, the ability of users to manipulate virtual objects with their eyes decreases, thus, decreasing the possibilities of interaction through eye gaze. The biomechanics model used here can be further extended to study muscular activity of eye muscles during immersion. It presents an efficient and flexible assessment tool for virtual environments.

Rationale and Objectives The aim of this study was to analyze the dominant factors affecting fatigue caused by soft-copy reading to identify a method for decreasing fatigue in clinical practice. Materials and Methods Two types of fatigue—fatigue in the central nervous system and subjective visual fatigue—were evaluated using a critical fusion frequency test and a questionnaire administered to 17 male radiologists before and after soft-copy reading. Reading-induced fatigue was assumed to be affected by 20 hypothetical factors associated with personal characteristics, time required for reading, content or amount of reading, and the reading environment. We used multiple linear regression analysis with a variable selection method to detect the best combination of factors capable of expressing variations in each of the measured fatigue values. The effects of the detected (dominant) factors on fatigue were also examined based on coefficients of the dominant factors in multiple regression models. Results Fatigue in the central nervous system decreased with a higher corrected visual acuity and a higher ambient illuminance in the reading room and was also affected by the type of monitor used. Visual fatigue was relieved when there was a larger difference in the brightness of the monitor and the surfaces surrounding the monitor and tended to be more severe when glasses rather than contact lenses were worn. Conclusions Increasing the ambient illuminance, using an appropriate type of monitor, improving the corrected visual acuity, and using contact lenses rather than eyeglasses could help decrease reading-induced fatigue in male radiologists.

Work Related Musculoskeletal Disorders (WMSDs) among office workers with intensive computer use is widespread and the prevalence of symptoms is growing. This randomized controlled trial investigated the effects of an office ergonomics training combined with a sit-stand workstation on musculoskeletal and visual discomfort, behaviors and performance. Participants performed a lab-based customer service job for 8 h per day, over 15 days and were assigned to: Ergonomics Trained (n = 11) or Minimally Trained (n = 11). The training consisted of: a 1.5-h interactive instruction, a sit/stand practice period, and ergonomic reminders. Ergonomics Trained participants experienced minimal musculoskeletal and visual discomfort across the 15 days, varied their postures, with significantly higher performance compared to the Minimally Trained group who had a significantly higher number of symptoms, suggesting that training plays a critical role. The ability to mitigate symptoms, change behaviors and enhance performance through training combined with a sit-stand workstation has implications for preventing discomforts in office workers.

Children's and adults' viewing comfort during stereoscopic three-dimensional film viewing and computer game playing was studied. Certain mild changes in visual function, heterophoria and near point of accommodation values, as well as eyestrain and visually induced motion sickness levels were found when single setups were compared. The viewing system had an influence on viewing comfort, in particular for eyestrain levels, but no clear difference between two- and three-dimensional systems was found. Additionally, certain mild changes in visual functions and visually induced motion sickness levels between adults and children were found. In general, all of the system-task combinations caused mild eyestrain and possible changes in visual functions, but these changes in magnitude were small. According to subjective opinions that further support these measurements, using a stereoscopic three-dimensional system for up to 2 h was acceptable for most of the users regardless of their age.

ResumenObjetivoSe realiza una revisión bibliográfica de de los nuevos dispositivos electrónicos, sus principios de funcionamiento y cómo estos influyen en el sistema visual.ConclusionesLos dispositivos electrónicos para la visualización de imágenes no producen un daño orgánico en el sistema visual, pero sí influyen en la aparición de fatiga o síntomas astenópicos si se usan de manera inadecuada o sin tomar las medidas de protección recomendadas.AbstractObjectiveA literature review on the new electronic devices, their operating principles and how these affect the visual system is performed.ConclusionsElectronic devices for displaying images not produce an organic damage to the visual system, but can produce fatigue or asthenopia without recommended protective measures.

Examine the effect of a multi-component office ergonomics intervention on visual symptom reductions.Office workers were assigned to either a group receiving a highly adjustable chair with office ergonomics training (CWT), a training-only group (TO) or a control group (C). A work environment and health questionnaire was administered 2 and 1 month(s) pre-intervention and 3, 6, and 12 months post-intervention. Multi-level statistical models tested hypotheses.The CWT intervention lowered daily visual symptoms (p 0.01) post-intervention. The TO group did not significantly differ from the control group. The CWT group differed significantly from the TO group (p = 0.01) post-intervention.Workers who received a highly adjustable chair and office ergonomics training had reduced visual symptoms and the effect was maintained through twelve months post-intervention. The lack of a training-only group effect supports implementing training in conjunction with the highly adjustable chair to reduce visual symptoms.

This study employs simulated electronic paper to investigate critical issues and focuses on improving legibility of display and reducing users' visual fatigue. Three critical factors--choice of surface treatment, ambient illumination, and bending curvature--are evaluated through the method of a letter-search task. The results show that subjects performed better on legibility and felt less visual fatigue with an anti-glare treatment. Choosing the better anti-glare treatment instead of the anti-reflection series can save significant cost for manufacturers. In addition, ambient lighting of 1500 lux is more appropriate for reading on electronic paper than an environment with extreme illumination (e.g., 8000 lux). The present study also found that curvature had no impact on legibility or visual fatigue. These evaluations of simulated electronic paper may provide manufacturers useful information in fulfilling ergonomic requirements for product design.

Rationale and Objectives The authors hypothesized that the current practice of radiology produces oculomotor fatigue that reduces diagnostic accuracy. Materials and Methods Testing this hypothesis required an ability to measure eyestrain. This capability was developed by measuring the visual accommodation of radiologists before and after diagnostic viewing work using an autorefractor that was capable of making multiple measurements of accommodation per second. Three radiologists and three residents focused on a simple target placed at near to far distances while accommodation was measured. The target distances varied from 20 to 183 cm from the eye. The data were collected prior to and after a day of digital diagnostic viewing. Results The results indicated that accommodation at near distances was significantly worse overall compared to far distances and was significantly worse after a day of digital reading at all distances. Conclusions Because diagnostic image interpretation is performed at near viewing distances, this inability to maintain focus on an image could affect diagnostic accuracy. As expected, younger residents had better accommodative accuracy than older radiologists.

This study investigated the effect of moving from single occupancy offices to a landscape environment. Thirty-four Visual Display Unit (VDU) operators reported significantly worsened condition of lighting and glare in addition to increased visual discomfort. For visual discomfort, the difference with 95% confidence interval was 10.7 (1.9-19.5) Visual Analog Scale (VAS) as group mean value. The most reasonable explanation for these results may be that the operators were glared from high luminance from the windows, when the Venetian blinds were not properly used. Glare was significantly correlated with visual discomfort, rs=0.35. Both illuminance and luminance in the work area, and contrast reduction on the VDU screen were in line with recommendations from CIE for VDU work. In a regression analysis, the visual discomfort explained 53% of the variance in the neck and shoulder pain. In the office landscape, the eye blink rate during habitual VDU work was recorded for 12 randomly selected operators from the 34 participants. A marked drop in eye blink rate during VDU work was found when this was compared to "easy conversation" (VDU work, mean=9.7 blinks per minute; "easy conversation," mean=21.4 blinks per minute). Participants reported many of the organizational and psychosocial conditions and work factors worse when landscape office was compared to single occupancy office. These factors may have influenced the musculoskeletal pain. However, the pain level was still low at 6 years and not significantly different when compared with the start of the study period, except for a small but significant increase in shoulder pain. In this study, visual discomfort is clearly associated with pain in the neck and shoulder area.

Purpose Fixation disparity measurement as a tool for analyzing the binocular visual system has taken very different approaches in the United States and Central Europe. In the United States, testing has primarily followed a motor approach, and resulting management has followed parameters established by graphical analysis closely. In German-speaking countries, a strong sensory-based analysis has been popular for decades, utilizing equipment rarely seen in the United States. Management in these countries has been almost exclusively directed toward prismatic prescription. Methods This report examines the instrumentation, underlying strategies, and management used in both the motor and sensory approaches to fixation disparity analysis. Testing protocols and management options are detailed for each approach. Conclusion Although both approaches agree that fixation disparity has the potential to reveal a more realistic view of binocular system functioning under normal viewing conditions than other systems of analysis, the approaches diverge in some very important ways, particularly in the understanding of the development of fixation disparity and its management. Whereas the philosophy underlying testing and management of the motor-based approach will be familiar to most clinicians in the United States, the sensory approach offers a very different perspective. It views the development of fixation disparity as a shift of correspondence within Panum’s area. In effect, this may be thought of as the oxymoron “a normal, anomalous correspondence”; that is, a shift of correspondence occurring in nonstrabismic patients. Management in these cases is based on accurate prism prescription to re-establish bifoveal fusion.

Background An increasing number of people seek medical attention for symptoms of visual discomfort due to computer vision syndrome (CVS). We compared the efficacy and adverse event rates of a new eye lubricant, OptiZen™ (InnoZen, Inc., polysorbate 80 0.5%) and Visine ® Original (Pfizer Consumer Healthcare, tetrahydrozoline HCL 0.05%). Methods In this double-blind parallel arm trial, 50 healthy men and women, ages 18 to 65 years, with symptoms of CVS who use a video display terminal for a minimum of 4 hours per day were randomized to OptiZen™ ( n = 25) or Visine ® Original ( n = 25), 1 to 2 drops b.i.d. for 5 days. The primary end points were ocular discomfort and adverse events. Results OptiZen™ and Visine ® Original had similar efficacy in alleviating symptoms of ocular discomfort (odds ratio of 1.23 [95% confidence interval, 0.63 to 2.42], P = 0.55). OptiZen™ and Visine ® Original were very similar with respect to odds ratios and 95% confidence interval (Cl) for each of the measurement times ( P = 0.72). Visine ® Original users reported a significantly higher incidence of temporary ocular stinging/burning immediately after drug instillation (28%, 7/25) than did OptiZen™ users (4%, 1/24) ( P = 0.05). Patients using OptiZen™ were 89% less likely to have stinging/burning effects than those patients using Visine ® Original (95% Cl: 0.01 to 0.95). Discussion OptiZen™ and Visine ® Original are effective at alleviating ocular discomfort associated with prolonged computer use. Adverse event findings suggest that OptiZen™ causes less ocular discomfort on instillation, potentially attributable to its milder ingredient profile.

Background While strabismologists are familiar with diagnostic evaluation of suspected blow out fractures, unsuspected blow out fractures may further complicate difficult cases of strabismus not clinically supposed to be related to orbital trauma. Methods According to a prospective protocol, we studied five adults presenting with diplopia, and one with convergence-related asthenopia. No patient recalled or had any clinical suspicion of orbital fracture at initial evaluation. Surface coil magnetic resonance imaging of the orbits was performed at 312 μm resolution, slice thickness 2 mm. Quasicoronal images in central gaze were supplemented with eccentric gaze positions, and sagittal and axial images as indicated. Results Five patients had incomitant hypertropia, and one had abducens paralysis. Magnetic resonance imaging disclosed previously unsuspected blow out fractures in all six patients. Three patients had medial wall fracture, one bilaterally. Two patients had inferior wall fractures, and one inferomedial. Although only one patient had an extraocular muscle displaced into a sinus, all had evidence of orbital connective tissue distortion in the region of the rectus extraocular muscle pulleys influencing muscle paths. These effects altered the presentations of more familiar pathologies such as superior oblique palsy. After learning of the MRI findings, most patients then recalled orbital trauma from as early as childhood. Conclusion Unsuspected blow out fractures occur and may confound the usual findings in complex strabismus. High-resolution orbital imaging can detect blow out fractures and clarify the pathophysiology, enabling appropriate surgical management.

A recently introduced optometric technique, colorimetry, enables the perceptual effects of ophthalmic tints to be evaluated subjectively, optimized, and then prescribed in tinted spectacles. The new technique is beneficial in reducing visual stress in patients with dyslexia and migraine. We describe an open trial designed to ascertain: (1) whether the colorimetry assessment, as it is now given, is safe for the investigation of photosensitive patients in optometry clinics where colorimetry equipment is most readily available, but where EEG control is not practical; (2) what proportion of patients with photosensitive epilepsy is likely to benefit to the extent already described in individual cases ; (3) whether a tint selected by colorimetry could be shown to reduce the incidence of paroxysmal epileptiform EEG activity in response to flicker and patterns, thereby validating the subjective methods and corroborating the reported seizure reduction. Twenty-four females and nine males (aged 12–43 years) took part. All the patients had suffered visually-provoked seizures, had exhibited a photoparoxysmal response on at least one previous EEG recording, and had received a diagnosis of photosensitive epilepsy. Twenty-two were currently experiencing seizures. A further EEG was recorded in all except seven cases: a routine resting record, followed by hyperventilation. Colorimetry was performed after hyperventilation and before photic stimulation. Twenty-three (70%) reported beneficial effects during colorimetry and were prescribed glasses. There was a preponderance of lenses with a rose or purple colour, in contrast to patients with dyslexia. Seventeen of the 23 patients were available at follow-up, an average of 2.4 years later. Thirteen (57%) reported benefits, and said they were still using the lenses. In six of the 13 the benefits were pronounced, including a reduction of dizziness from fluorescent lighting, elimination of aura when using computer screens etc. Only in three cases was there a reduction in seizures that could reasonably be attributed to the use of lenses; in two of these cases no medications were prescribed, and in the third the medications remained unchanged for four years, two before and two after the introduction of the glasses. In an additional four cases a reduction in seizures was observed but medication had been changed. There was a modest reduction in EEG photosensitivity with the coloured lenses but also to an equivalent or lesser extent with grey in all of the eight patients examined in this way. One patient had seizures during colorimetry, but the seizures were not accompanied by scalp EEG changes.

Purpose To determine whether eyestrain symptoms predict eye conditions in 6-year-old children. Design Cross-sectional population-based study. Methods Reports of eyestrain symptoms were sought in parental questionnaires; 1740 children (79% response) underwent eye examinations (visual acuity, cover testing, cycloplegic autorefraction, and fundus examination). Results Eyestrain information was available for 1448 children; 220 (15.2%) reported eyestrain symptoms, including 60 (3.4%) who reported near work-associated headaches. Most children (82.3%) had a normal eye examination, while refractive errors, amblyopia, and strabismus were found in 15.0%, 3.6%, and 7.3%, respectively. Corresponding rates for children without eyestrain were 9.9%, 1.4%, and 1.8%, respectively. Moreover, 78.7% of children with refractive errors, 68% with amblyopia, and 58% with strabismus reported no eyestrain. Conclusions Most children complaining of eyestrain had a normal eye examination; whereas most children with refractive error, amblyopia, or strabismus were free of eyestrain, making this complaint a poor marker of eye conditions in young children.

Occupational health hazards in ultrasonography are becoming more prevalent as the field continues to grow. Eye strain, musculoskeletal pain or injury, carpal tunnel syndrome, repetitive strain injuries, stress, burnout, and other hazards have been addressed as concerns in other studies and surveys. These topics are discussed, as well as the possible preventive measures that may be used to maximize and maintain the ultrasonographer's well-being throughout his or her career. (J Am Soc Echocardiogr 1997;10:363-6.)

To evaluate the learning curve and fatigue effect of flicker defined form (FDF) perimetry.Prospective cross-sectional study.One hundred forty-one eyes of 75 healthy subjects were included in the study. Every subject was measured 3 times on 3 different days within 3 months. Differences among the tests were analyzed for mean sensitivity (MS), mean deviation (MD), pattern standard deviation (PSD), reliability indices, test duration, and test points5% and0.5% in 75 right eyes on the basis of linear mixed models for repeated measurements. To assess the effect of fatigue, differences of MS, MD, and PSD values between 66 left and right eyes were evaluated regarding alterations between these 3 examinations.After 3 test sessions, significant improvements were found in MS and MD among all 3 tests (P ≤ .01), and in PSD between test 1 and test 3 (P = .02). Test duration decreased significantly between tests 1 and 3 (P = .01); fixation-loss errors decreased significantly between tests 2 and 3 and between tests 1 and 3 (P = .02, respectively). Test points with p0.5% decreased significantly between tests 1 and 2 (P = .04) and 1 and 3 (P = .01) When comparing both eyes, MS, MD, and PSD were significantly better in first than in second eyes examined.There exist significant learning and fatigue effects for repeated flicker defined form perimetry. For good and reliable results on FDF perimetry, at least 3 tests should be performed in an individual. Between the tests of both eyes, a rest should be offered.

Lees screen restrictions of non-specific origin, including apparent restrictions of the SR, IR, and LR muscles, were reported last year by Labow et al. In this complementary study, the authors examined eight apparently healthy subjects who had no history of ocular or psychiatric problems, eight psychiatric patients, and eight who had had a CNS disorder or had suffered cerebral trauma. Comparison of the Lees screen findings, visual fields, and accommodative defects of these patients revealed significant restriction of the Lees screen fields in only those patients who had symptoms of asthenopia (including all in the third group). Thus, such restriction does not depend on emotional state.

Vertical prisms are useful in the permanent or temporary alleviation of asthenopic symptoms arising from a vertical misalignment of the visual axes. A wide variety of both comitant and noncomitant hyperdeviations may be candidates for vertical prism use. Vertical prism strength is seldom difficult to compute and when properly employed, vertical prisms do not lead to unsightly spectacles.

Dermatochalasis and blepharochalasis of the upper lids, in addition to producing a cosmetic defect, causes asthenopic symptoms. A blepharoplasty for dermatochalasis removes skin only. Blepharochalasis removes protruding fat, tightens the orbital septum, and, in addition, when indicated removes excess skin. The surgical techniques for these procedures are presented.