Effect of the accommodation-vergence conflict on vergence eye movements

With the broader use of stereoscopic displays, a flurry of research activity about the accommodation-vergence conflict has emerged to highlight the implications for the human visual system. In stereoscopic displays, the introduction of binocular disparities requires the eyes to make vergence movements. In this study, we examined vergence dynamics with regard to the conflict between the stimulus-to-accommodation and the stimulus-to-vergence. In a first experiment, we evaluated the immediate effect of the conflict on vergence responses by presenting stimuli with conflicting disparity and focus on a stereoscopic display (i.e. increasing the stereoscopic demand) or by presenting stimuli with matched disparity and focus using an arrangement of displays and a beam splitter (i.e. focus and disparity specifying the same locations). We found that the dynamics of vergence responses were slower overall in the first case due to the conflict between accommodation and vergence. In a second experiment, we examined the effect of a prolonged exposure to the accommodation-vergence conflict on vergence responses, in which participants judged whether an oscillating depth pattern was in front or behind the fixation plane. An increase in peak velocity was observed, thereby suggesting that the vergence system has adapted to the stereoscopic demand. A slight increase in vergence latency was also observed, thus indicating a small decline of vergence performance. These findings offer a better understanding and document how the vergence system behaves in stereoscopic displays. We describe what stimuli in stereo-movies might produce these oculomotor effects, and discuss potential applications perspectives.

Change in convergence and accommodation after two weeks of eye exercises in typical young adults

BACKGROUND

Although eye exercises appear to help heterophoria, convergence insufficiency, and intermittent strabismus, results can be confounded by placebo, practice, and encouragement effects. This study assessed objective changes in vergence and accommodation responses in naive young adults after a 2-week period of eye exercises under controlled conditions to determine the extent to which treatment effects occur over other factors.

METHODS

Asymptomatic young adults were randomly assigned to one of two no-treatment (control) groups or to one of six eye exercise groups: accommodation, vergence, both, convergence in excess of accommodation, accommodation in excess of convergence, and placebo. Subjects were tested and retested under identical conditions, except for the second control group, who were additionally encouraged. Objective accommodation and vergence were assessed to a range of targets moving in depth containing combinations of blur, disparity, and proximity/looming cues.

RESULTS

A total of 156 subjects were included. Response gain improved more for less naturalistic targets where more improvement was possible. Convergence exercises improved vergence for near across all targets (P = 0.035). Mean accommodation changed similarly but nonsignificantly. No other treatment group differed significantly from the nonencouraged control group, whereas encouraging effort produced significantly increased vergence (P = 0.004) and accommodation (P = 0.005) gains in the second control group.

CONCLUSIONS

True treatment effects were small, significantly better only after vergence exercises to a nonaccommodative target, and rarely related to the response they were designed to improve. Exercising accommodation without convergence made no difference to accommodation to cues containing detail. Additional effort improved objective responses the most.

Smooth pursuit eye movements in children with strabismus and in children with vergence deficits

Purpose

The objective of our study was to examine horizontal smooth pursuit performance in strabismic children and in children with vergence deficits, and to compare these data with those recorded in a group of control age-matched children.

Methods

Binocular eye movements were recorded by video-oculography in ten strabismic children (mean age: 9.8±0.8) and seven children with vergence deficits (mean age: 10.8±0.6). Data were compared to that of age-matched control children (mean age: 9.8±0.8 years).

Results

Catch-up saccades amplitude in strabismic children and in children with vergence deficits were significantly higher than in control age-matched children. Moreover, in strabismic children the amplitude of catch-up saccades was significantly higher in rightward than in leftward direction. The number of catch-up saccades was also significantly higher in rightward than in leftward direction. The gain value of pursuits in rightward direction was significantly higher in the right eye than in the left one; for the right eye, the gain value was significantly higher in rightward than in leftward direction. Binocular coordination of pursuit was better in control age-matched children than in children with vergence deficits and than in strabismic children.

Conclusions

Binocular coordination of pursuit is abnormal in children with vergence deficits and worse in strabismic children. Binocular vision plays an important role in improving binocular coordination of pursuit.

Ocular motor score a novel clinical approach to evaluating ocular motor function in children

PURPOSE

Ocular motility disturbances are common in a number of neuropaediatric and neurometabolic disorders. Assessment of ocular motor function can be a source of information for diagnosis and follow-up of these patients.

AIM

To evaluate a new clinical ocular motor function test: ocular motor score (OMS) and provide reference values in children and young adults without known ocular or neurological disorders.

MATERIAL AND METHODS

A total of 233 children and young adults, 103 males and 130 females between the ages of 6 months and 19 years, were assessed according to a specific OMS protocol. They were divided into four different age groups: 0.5-3, 4-6, 7-10 and 11-19 years. The OMS protocol consists of 15 different subtests evaluating ocular motor function, and a total score of minimum 0 up to max 15 can be obtained: the minimum score, 0, is considered normal while 1 represents an abnormal function.

RESULTS

The median OMS in the whole reference group was 0.3 (range 0-4.8). The median OMS in the different age groups, starting with the youngest, was: 0.9 (range 0.3-4.8), 0.3 (range 0-3.4), 0.3 (range 0-2.3) and 0 (range 0-3.5), respectively. The youngest subjects, aged 0.5-3, showed a significantly higher total OMS compared with the other age groups (p < 0.001).

CONCLUSION

This study provides reference values for the OMS test in a population aged 0.5-19 years. The test may be valuable as a screening tool for identification and follow-up of ocular motor dysfunction in children and young adults.

Why do only some hyperopes become strabismic?

Children with hyperopia greater than +3.5 diopters (D) are at increased risk for developing refractive esotropia. However, only approximately 20% of these hyperopes develop strabismus. This review provides a systematic theoretical analysis of the accommodation and vergence oculomotor systems with a view to understanding factors that could either protect a hyperopic individual or precipitate a strabismus. The goal is to consider factors that may predict refractive esotropia in an individual and therefore help identify the subset of hyperopes who are at the highest risk for this strabismus, warranting the most consideration in a preventive effort.

Binocular coordination of saccades during reading in children with clinically assessed poor vergence capabilities

Prior studies have pointed toward a link between the saccadic and vergence systems, coordinating binocular saccadic movements. Recent studies have shown that vergence deficits in children induce poor binocular coordination during saccades, but none of them have studied ocular motility in children during a daily task such as reading. The present study tests whether vergence deficits in children perturb binocular coordination of saccades and fixation during reading. Our second objective was to explore whether vergence training could improve the quality of binocular coordination. Twelve patients (from 7.3 to 13.4 years old) complaining from vertigo but without vestibular and neurological pathology underwent orthoptic tests and were selected for our study when they presented vergence deficits. Eye movements were recorded during a reading task with a Mobile EyeBrain® Tracker video-oculography system. Data were compared to twelve age-matched controls with normal orthoptic values. While there was no statistically significant difference in saccade amplitudes between the two groups (p=0.29), patients showed higher disconjugacy during and after the saccades compared to controls (p<0.001). After orthoptic training, six patients out of the first 12 examined came back for a second oculomotor test. All showed a significant improvement of their binocular saccade coordination. We suggest that the larger disconjugacy during reading observed in patients before training could be due to poor vergence as initially assessed by orthoptic examination. Such findings support the hypothesis of a tight relationship between the saccadic and vergence systems for controlling the binocular coordination of saccades. The improvement reported after orthoptic training is in line with the hypothesis of an adaptative interaction on a premotor level between the saccadic and vergence system.

Visual fatigue and discomfort after stereoscopic display viewing

PURPOSE

Different types of stereoscopic video displays have recently been introduced. We measured and compared visual fatigue and visual discomfort induced by viewing two different stereoscopic displays that either used the pattern retarder-spatial domain technology with linearly polarized three-dimensional technology or the circularly polarized three-dimensional technology using shutter glasses.

METHODS

During this observational cross-over study performed at two subsequent days, a video was watched by 30 subjects (age: 20-30 years). Half of the participants watched the screen with a pattern retard three-dimensional display at the first day and a shutter glasses three-dimensional display at the second day, and reverse. The study participants underwent a standardized interview on visual discomfort and fatigue, and a series of functional examinations prior to, and shortly after viewing the movie. Additionally, a subjective score for visual fatigue was given.

RESULTS

Accommodative magnitude (right eye: p < 0.001; left eye: p = 0.01), accommodative facility (p = 0.008), near-point convergence break-up point (p = 0.007), near-point convergence recover point (p = 0.001), negative (p = 0.03) and positive (p = 0.001) relative accommodation were significantly smaller, and the visual fatigue score was significantly higher (1.65 ± 1.18 versus 1.20 ± 1.03; p = 0.02) after viewing the shutter glasses three-dimensional display than after viewing the pattern retard three-dimensional display.

CONCLUSIONS

Stereoscopic viewing using pattern retard (polarized) three-dimensional displays as compared with stereoscopic viewing using shutter glasses three-dimensional displays resulted in significantly less visual fatigue as assessed subjectively, parallel to significantly better values of accommodation and convergence as measured objectively.

Association between reading speed, cycloplegic refractive error, and oculomotor function in reading disabled children versus controls

BACKGROUND

Approximately one in ten students aged 6 to 16 in Ontario (Canada) school boards have an individual education plan (IEP) in place due to various learning disabilities, many of which are specific to reading difficulties. The relationship between reading (specifically objectively determined reading speed and eye movement data), refractive error, and binocular vision related clinical measurements remain elusive.

METHODS

One hundred patients were examined in this study (50 IEP and 50 controls, age range 6 to 16 years). IEP patients were referred by three local school boards, with controls being recruited from the routine clinic population (non-IEP patients in the same age group). A comprehensive eye examination was performed on all subjects, in addition to a full binocular vision work-up and cycloplegic refraction. In addition to the cycloplegic refractive error, the following binocular vision related data was also acquired: vergence facility, vergence amplitudes, accommodative facility, accommodative amplitudes, near point of convergence, stereopsis, and a standardized symptom scoring scale. Both the IEP and control groups were also examined using the Visagraph III system, which permits recording of the following reading parameters objectively: (i) reading speed, both raw values and values compared to grade normative data, and (ii) the number of eye movements made per 100 words read. Comprehension was assessed via a questionnaire administered at the end of the reading task, with each subject requiring 80% or greater comprehension.

RESULTS

The IEP group had significantly greater hyperopia compared to the control group on cycloplegic examination. Vergence facility was significantly correlated to (i) reading speed, (ii) number of eye movements made when reading, and (iii) a standardized symptom scoring system. Vergence facility was also significantly reduced in the IEP group versus controls. Significant differences in several other binocular vision related scores were also found.

CONCLUSION

This research indicates there are significant associations between reading speed, refractive error, and in particular vergence facility. It appears sensible that students being considered for reading specific IEP status should have a full eye examination (including cycloplegia), in addition to a comprehensive binocular vision evaluation.

Convergence insufficiency-a major review

Convergence insufficiency is a common binocular vision disorder affecting approximately 5% of the population in the United States. It is often associated with a host of symptoms that occur when doing near work, such as reading and computer viewing. This article reviews the existing literature on convergence insufficiency including etiology, diagnosis, sensorimotor findings, and management.

Immaturity of the oculomotor saccade and vergence interaction in dyslexic children: evidence from a reading and visual search study

Studies comparing binocular eye movements during reading and visual search in dyslexic children are, at our knowledge, inexistent. In the present study we examined ocular motor characteristics in dyslexic children versus two groups of non dyslexic children with chronological/reading age-matched. Binocular eye movements were recorded by an infrared system (mobileEBT®, e(ye)BRAIN) in twelve dyslexic children (mean age 11 years old) and a group of chronological age-matched (N = 9) and reading age-matched (N = 10) non dyslexic children. Two visual tasks were used: text reading and visual search. Independently of the task, the ocular motor behavior in dyslexic children is similar to those reported in reading age-matched non dyslexic children: many and longer fixations as well as poor quality of binocular coordination during and after the saccades. In contrast, chronological age-matched non dyslexic children showed a small number of fixations and short duration of fixations in reading task with respect to visual search task; furthermore their saccades were well yoked in both tasks. The atypical eye movement's patterns observed in dyslexic children suggest a deficiency in the visual attentional processing as well as an immaturity of the ocular motor saccade and vergence systems interaction.

Evidence that convergence rather than accommodation controls intermittent distance exotropia

PURPOSE

This study considered whether vergence drives accommodation or accommodation drives vergence during the control of distance exotropia for near fixation. High accommodative convergence to accommodation (AC/A) ratios are often used to explain this control, but the role of convergence to drive accommodation (the CA/C relationship) is rarely considered. Atypical CA/C characteristics could equally, or better, explain common clinical findings.

METHODS

Nineteen distance exotropes, aged 4-11 years, were compared while controlling their deviation with 27 non-exotropic controls aged 5-9 years. Simultaneous vergence and accommodation responses were measured to a range of targets incorporating different combinations of blur, disparity and looming cues at four fixation distances between 2 m and 33 cm. Stimulus and response AC/A and CA/C ratios were calculated.

RESULTS

Accommodation responses for near targets (p = 0.017) and response gains (p = 0.026) were greater in the exotropes than in the controls. Despite higher clinical stimulus AC/A ratios, the distance exotropes showed lower laboratory response AC/A ratios (p = 0.02), but significantly higher CA/C ratios (p = 0.02). All the exotropes, whether the angle changed most with lenses ('controlled by accommodation') or on occlusion ('controlled by fusion'), used binocular disparity not blur as their main cue to target distance.

CONCLUSIONS

Increased vergence demand to control intermittent distance exotropia for near also drives significantly more accommodation. Minus lens therapy is more likely to act by correcting overaccommodation driven by controlling convergence, rather than by inducing blur-driven vergence. The use of convergence as a major drive to accommodation explains many clinical characteristics of distance exotropia, including apparently high near stimulus AC/A ratios.

High-resolution far-field integral-imaging camera by double snapshot

In multi-view three-dimensional imaging, to capture the elemental images of distant objects, the use of a field-like lens that projects the reference plane onto the microlens array is necessary. In this case, the spatial resolution of reconstructed images is equal to the spatial density of microlenses in the array. In this paper we report a simple method, based on the realization of double snapshots, to double the 2D pixel density of reconstructed scenes. Experiments are reported to support the proposed approach.

Ocular motor and sensory function in Parkinson's disease

PURPOSE

To evaluate the effect of dopaminergic medication and deep brain stimulation on ocular function in Parkinson's disease (PD) and to measure vision-related quality of life in subjects with PD.

DESIGN

Prospective, comparative case series.

PARTICIPANTS AND CONTROLS

Twenty-seven PD and 16 control subjects were recruited.

METHODS

Visual acuity, ocular motor function, convergence, and vision-related quality of life using the 25-item National Eye Institute Visual Function Questionnaire (VFQ-25) were measured. Visual sensory and motor measurements were obtained during the on and off states of PD dopaminergic treatment.

MAIN OUTCOME MEASURES

Convergence ability and vision-related quality of life.

RESULTS

The PD subjects had a mean age of 58.8 years; 30% were female. Their mean duration of PD was 10.9 ± 6.8 years. The control subjects had a mean age of 61.6 years; 56% were female. There was no difference in visual acuity, contrast sensitivity, or color vision of the PD subjects in their on state compared with controls. Convergence amplitudes measured with base-out prism were significantly poorer in PD subjects in their on state compared with controls (24.1 ± 8 Δ vs. 14.8 ± 10.3 Δ; P = 0.003). The mean composite VFQ-25 score was significantly worse in the PD subjects compared with the controls (87.1 ± 8.69 vs. 96.6 ± 3.05; P = 0.0001). Comparing the PD subjects in their on with their off states, there was no difference in distance exodeviation, near exodeviation, or ocular ductions. Mean convergence amplitudes and near point of convergence were better in the on state compared with the off state: 14.8 ± 10.3 Δ versus 10.7 ± 9.0 Δ (P = 0.0006) and 13.1 ± 9.1 cm versus 18.1 ± 12.2 cm (P = 0.002), respectively.

CONCLUSIONS

Convergence ability is significantly poorer in PD subjects in both the on and off states compared with controls, but improves significantly with systemic dopaminergic treatment. Ocular motor function in PD subjects fluctuates in response to treatment, which complicates ophthalmic management. Parkinson's disease subjects have a significant reduction in vision-related quality of life, especially with near activities, that is not associated with visual acuity.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Fusional convergence in childhood intermittent exotropia

PURPOSE

To evaluate fusional convergence and associations with control in children with intermittent exotropia (XT).

DESIGN

Retrospective case series.

METHODS

Sixty-four children (median age 7 years) with intermittent XT were identified with measures of angle of deviation, control (using a previously reported 0-to-5-point scale), and fusional convergence at a single examination. Total convergence was defined as the sum of the angle of deviation plus additional convergence in reserve. Mean values were compared with published normals. A fusion reserve ratio was calculated as "convergence reserve divided by angle of deviation." Relationships of control score with total amplitude, reserve, recovery, and fusion reserve ratio were assessed using Spearman rank correlations.

RESULTS

Convergence differed from normals in children with intermittent XT: total convergence was higher at distance (33 prism diopters [pd] vs 17 pd, P<.0001) and near (38 pd vs 18 pd, P<.0001) whereas convergence reserve was lower at distance (7 pd vs 17 pd; P<.0001). There was a strong correlation between fusion reserve ratio and control score at distance (R=-0.75, P<.0001) and near (R=-0.66, P<.0001).

CONCLUSIONS

Children with intermittent XT have subnormal convergence reserves at distance. The fusion reserve ratio correlates well with control and may be useful in grading the severity of intermittent XT.

The zone of comfort: Predicting visual discomfort with stereo displays

Recent increased usage of stereo displays has been accompanied by public concern about potential adverse effects associated with prolonged viewing of stereo imagery. There are numerous potential sources of adverse effects, but we focused on how vergence-accommodation conflicts in stereo displays affect visual discomfort and fatigue. In one experiment, we examined the effect of viewing distance on discomfort and fatigue. We found that conflicts of a given dioptric value were slightly less comfortable at far than at near distance. In a second experiment, we examined the effect of the sign of the vergence-accommodation conflict on discomfort and fatigue. We found that negative conflicts (stereo content behind the screen) are less comfortable at far distances and that positive conflicts (content in front of screen) are less comfortable at near distances. In a third experiment, we measured phoria and the zone of clear single binocular vision, which are clinical measurements commonly associated with correcting refractive error. Those measurements predicted susceptibility to discomfort in the first two experiments. We discuss the relevance of these findings for a wide variety of situations including the viewing of mobile devices, desktop displays, television, and cinema.

Short-term adaptations of the dynamic disparity vergence and phoria systems

The ability to adapt is critical to survival and varies between individuals. Adaptation of one motor system may be related to the ability to adapt another. This study sought to determine whether phoria adaptation was correlated with the ability to modify the dynamics of disparity vergence. Eye movements from ten subjects were recorded during dynamic disparity vergence modification and phoria adaptation experiments. Two different convergent stimuli were presented during the dynamic vergence modification experiment: a test stimulus (4° step) and a conditioning stimulus (4° double step). Dynamic disparity vergence responses were quantified by measuring the peak velocity (°/s). Phoria adaptation experiments measured the changes in phoria over a 5-min period of sustained fixation. The maximum velocity of phoria adaptation was determined from an exponential fit of the phoria data points. Phoria and dynamic disparity vergence peak velocity were both significantly modified (P < 0.001). The maximum velocity of phoria adaptation was significantly correlated with the changes in convergence peak velocity (r > 0.89; P < 0.001). There was a strong correlation between the ability to adaptively adjust two different oculomotor parameters: a tonic and dynamic component. Future studies should investigate additional interactions between these parameters, and the ability to adaptively change other oculomotor systems such as the saccadic or smooth pursuit system. Understanding the ability to modify phoria, dynamic disparity vergence, and other oculomotor parameters can yield insights into the plasticity of short-term adaptation mechanisms.

Surgical outcomes in convergence insufficiency-type exotropia

PURPOSE

To determine the efficacy of different types of strabismus surgeries in patients with convergence insufficiency (CI)-type exotropia, according to their response to diagnostic monocular occlusion.

DESIGN

Retrospective cohort study.

PARTICIPANTS

Sixty-five patients with CI-type exotropia with near-distance differences of ≥10 prism diopters (PD) who underwent strabismus surgery.

METHODS

Patients were divided into 3 groups according to their response to monocular occlusion: (1) true-CI group: near-distance differences ≥10 PD before and after occlusion; (2) masked-CI group: near-distance differences <10 PD before occlusion and ≥10 PD after occlusion; and (3) pseudo-CI group: near-distance differences ≥10 PD before occlusion and <10 PD after occlusion. Either bilateral lateral rectus recession based on near measurements with 1 mm augmentation (BLR) or unilateral medial rectus resection based on the near deviation with lateral rectus recession based on the distant deviation (RR) was performed.

MAIN OUTCOME MEASURES

Cumulative probabilities of success, near-distance differences of exodeviation, rate of recurrence per person-year, and risk factors of recurrence.

RESULTS

There were 24 children in the true-CI group, 19 children in the masked-CI group, and 22 children in the pseudo-CI group. The cumulative probabilities of success at 2 years after BLR versus RR were 61% versus 100% in the true-CI group, 58% versus 100% in the masked-CI group, and 77% versus 71% in the pseudo-CI group. The RR procedure was significantly more successful than the BLR procedure in the true-CI and masked-CI groups.

CONCLUSIONS

Successful outcome in CI-type exotropia was closely related to the patients' response to monocular occlusion. In patients with CI-type exotropia maintained after monocular occlusion, unilateral resection-recession based on near-distance measurements is recommended.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Intermittent exotropia: facts, opinions, and unknowns

INTRODUCTION

Intermittent exotropia (IXT) can be a controversial topic, often eliciting lively discussion. This lecture will discuss its definition, incidence, age of onset, presentation, natural variation, criteria for deterioration, goals of treatment, effectiveness of surgical treatment, types of surgical treatment, and unwanted effects of surgical treatment.

METHOD

Results from the scientific literature, opinions of respected colleagues, the opinion of the author, and the results of live polling of the audience during the John Pratt-Johnson lecture are presented.

RESULTS

IXT is defined as an exotropia that is present intermittently predominantly for distance. Its incidence is about 1% and it usually has an onset before age 5. Patients often present because of concern regarding the appearance of the eye misalignment. There is natural variation in the control of IXT, the angle of IXT, and the amount of stereopsis. Criteria that denote deterioration are increasing frequency of IXT, progressively and consistently increasing angle of IXT, loss of binocular vision, and increasing concern regarding the patient's appearance and its effect on social interaction. Goals of treatment are to retain equal or nearly equal vision, to obtain acceptable cosmesis, and to retain binocular vision. The long-term success of surgical treatment is not well proven. Persistent postoperative overcorrection is an unwanted effect of surgical treatment.

CONCLUSION

The inherent biologic variation that occurs when measuring the components of IXT makes it difficult to be dogmatic about IXT, particularly when trying to decide when deterioration is occurring.

Central crosstalk for somatic tinnitus: abnormal vergence eye movements

Background

Frequent oulomotricity problems with orthoptic testing were reported in patients with tinnitus. This study examines with objective recordings vergence eye movements in patients with somatic tinnitus patients with ability to modify their subjective tinnitus percept by various movements, such as jaw, neck, eye movements or skin pressure.

Methods

Vergence eye movements were recorded with the Eyelink II video system in 15 (23–63 years) control adults and 19 (36–62 years) subjects with somatic tinnitus.

Findings

1) Accuracy of divergence but not of convergence was lower in subjects with somatic tinnitus than in control subjects. 2) Vergence duration was longer and peak velocity was lower in subjects with somatic tinnitus than in control subjects. 3) The number of embedded saccades and the amplitude of saccades coinciding with the peak velocity of vergence were higher for tinnitus subjects. Yet, saccades did not increase peak velocity of vergence for tinnitus subjects, but they did so for controls. 4) In contrast, there was no significant difference of vergence latency between these two groups.

Interpretation

The results suggest dysfunction of vergence areas involving cortical-brainstem-cerebellar circuits. We hypothesize that central auditory dysfunction related to tinnitus percept could trigger mild cerebellar-brainstem dysfunction or that tinnitus and vergence dysfunction could both be manifestations of mild cortical-brainstem-cerebellar syndrome reflecting abnormal cross-modality interactions between vergence eye movements and auditory signals.

[Comparison of effects of periocular region dry and wet warming on visual acuity and near reflex]

PURPOSE

To investigate the influence of warming the periocular region for 10 minutes after visual display terminal (VDT) work on the near reflex, and the differences in influence between lid closure, dry and wet warming, and the amounts of water vapor.

SUBJECTS AND METHODS

Subjects in the first trial were 10 healthy volunteers (10 eyes). Following VDT, subjects wore either a warming eye steamer (water vapor: 200 mg/10 min) or an eye mask with their eyelids closed for 10 minutes. Subjects in the second trial were 5 healthy volunteers (5 eyes). Following VDT, subjects applied either a dry-warming sheet (water vapor: 0 mg/10 min) or a wet-warming sheet (water vapor: 20, 35, 160 and 200 mg/10 min) to there eyelids and the periocular region for 10 minutes. In both experiments, subjective amplitude of accommodation, pupillary reaction, convergence reaction, near vision, and breakup time were measured before and immediately after VDT work and after 2 experimental settings.

RESULTS

The warming eye steamer significantly improved amplitude of accommodation (p<0.05), and near vision (p<0.05). Warming the periocular region with water vapor improved subjective amplitude of accommodation, and near vision, the effect of which depended on the amount of water vapor (p<0.05).

CONCLUSIONS

Warming the periocular region with water vapor improved subjective amplitude of accommodation, near vision and the effect depended on the amount of water vapor.