Relationship between Eye Frailty and Physical, Social, and Psychological/Cognitive Weaknesses among Community-Dwelling Older Adults in Japan.

This study investigated the relationship between eye frailty and physical, social, and psychological/cognitive weaknesses among older adults in Japan. The participants were 192 community-dwelling older adult women. We measured handgrip strength, walking speed, and skeletal muscle mass; additionally, their physical, social, and psychological/cognitive frailties were surveyed using questionnaires. Eye frailty self-checks were used to assess eye frailty. Exploratory and confirmatory factor analyses were employed to verify the validity of the eye frailty self-checks. Eye frailty prevalence and related factors were investigated by conducting a binomial logistic regression analysis, with eye frailty as the dependent variable. The factor analysis results showed that a model could be constructed with the two factors of visual acuity or contrast and visual field. The model's goodness of fit was acceptable, supporting the validity of the self-checking construct. The Kihon checklist was the only variable with a significant relationship to eye frailty. Regarding the relationship between eye frailty and subordinate items of the Kihon checklist, social withdrawal [odds ratio (OR) 2.437, 95% confidence interval 1.145-5.188], cognitive function (OR 2.047, 95%CI 1.051-3.984), and depressed mood (OR 1.820, 95%CI 1.163-2.848) were significant. Eye frailty can be considered a factor reflecting the existence of social and psychological/cognitive frailties.

Investigation of the pathophysiology of the retina and choroid in Parkinson's disease by optical coherence tomography.

PURPOSE: The pathology of Parkinson's disease (PD) is suspected to affect the retina and choroid. We investigated changes in the retina and choroid of patients with PD using optical coherence tomography. METHODS: We examined 14 patients with PD and 22 patients without PD. Patients without PD had no ophthalmic disease other than cataracts. In addition, it was also confirmed that there was no neurodegenerative disease. The retinal nerve fiber layer, ganglion cell layer + inner plexiform layer, and choroidal thickness were compared between both groups. Additionally, the choroidal image was divided into the choroid area, luminal area, and interstitial area using the binarization method, and the area of each region and the percentage of luminal area in the choroid area were analyzed. RESULTS: Patients with PD had a significantly thinner ganglion cell layer + inner plexiform layer compared to those without PD. The choroid area, luminal area, and interstitial area were significantly decreased in patients with PD compared to those without PD. Seven patients with PD who were successfully followed up showed decreased retinal nerve fiber layer and interstitial area after 3 years. CONCLUSION: Autonomic nervous disorders and neurodegeneration in PD can cause thinning of the retina and choroid, as well as a reduction in the choroid area.

Comparison of refractive value and pupil size under monocular and binocular conditions between the Spot Vision Screener and binocular open-field autorefractor.

We determined the repeatability-reproducibility of refraction values and pupil size measured using the Spot Vision Screener and compare the obtained values with those measured using the binocular open-field autorefractor Grand Seiko WAM 5500 in healthy adults. This cross-sectional study included 22 eyes of 22 healthy adults with emmetropia to myopia. For each participant, spherical equivalent value, cylindrical value, and pupil size were measured in the right eye using the Spot Vision Screener and Grand Seiko autorefractor devices by two different orthoptists under two conditions: monocular and binocular (three consecutive refraction measurements). Repeatability-reproducibility of values measured using both devices were evaluated using intra-class correlation coefficients (ICCs). The mean spherical equivalent value measured using the Spot Vision Screener was -2.79D in the monocular condition and -2.69D in binocular condition, which showed a small significant difference to those measured using the Grand Seiko autorefractor (-2.98D and -2.93D, respectively). The mean cylindrical value measured using the Spot Vision Screener was -0.59D in the monocular condition and -0.52D in the binocular condition, which showed a small significant difference compared with those measured using the Grand Seiko autorefractor in the binocular condition (-0.70D and -0.75D, respectively). Correlation coefficients of the spherical equivalent values, cylindrical values, and pupil sizes measured using both devices were R=0.959 (P<0.001), R=0.243 (P=0.260) and R=0.917 (P<0.001), respectively, in the monocular condition and R=0.962 (P<0.001), R=0.444 (P=0.040), and R=0.832 (P<0.001), respectively, in the binocular condition. ICC values of spherical equivalent value in intra-rater or inter-rater were more than 0.99 in both devices and conditions. ICC values of cylindrical values under the binocular condition in the Spot Vision Screener were 0.636 in intra-rater and 0.574 in inter-rater, which were lower than those of the Grand Seiko autorefractor (0.874 and 0.839, respectively). ICC values of pupil sizes under the binocular condition in the Spot Vision Screener were 0.871 in intra-rater and 0.760 in inter-rater, which were lower than those of the Grand Seiko autorefractor (0.967 and 0.943, respectively). The refractive value and pupil size obtained using the Spot Vision Screener showed high repeatability and reproducibility and were similar to the values obtained using the Grand Seiko autorefractor. Thus, the Spot Vision Screener, an automated vision screener, is a reliable portable refractor and pupillometry device for measuring refractive errors in clinical settings.

Effect of Pupil Size and Binocular Viewing on Accommodative Gain in Emmetropia and Myopia.

PURPOSE: To evaluate the differences in accommodative gain in response to different accommodative stimuli and determine the effects of pupil size, binocular viewing, and inherent eye refraction on accommodative gain. METHODS: This study enrolled 47 healthy young adults (emmetropia: 21 eyes, myopia: 26 eyes). Refractive value and pupil size during accommodative stimulus were measured using an open-viewing type auto-refractor (Grand Seiko WAM-5500). The subject was continuously presented with six stimuli (0D, 1D, 2D, 3D, 4D, and 5D) in front of the eye. Measurements were performed under three conditions. Condition 1: Monocular status with complete occlusion of the non-viewing eye; Condition 2: Monocular status with occlusion of the non-viewing eye by translucent occluder; Condition 3: Binocular status. RESULTS: In the emmetropia group, there was no significant difference in accommodative gain between conditions 1 and 2 (p > .05), but conditions 2 and 3 were significantly different (p < .05). In the myopia group, accommodative gain was significantly different between conditions 1 and 2 with stimuli 3D, 4D, and 5D (p < .05), but conditions 2 and 3 were not significantly different (p > .05). CONCLUSIONS: The effects of pupil size and binocular viewing on accommodative gain differed between emmetropia and myopia.

Development of a new intraocular lens power calculation method based on lens position estimated with optical coherence tomography.

A new method is developed and validated for intraocular lens (IOL) power calculation based on paraxial ray tracing of the postoperative IOL positions, which are obtained with the use of anterior segment optical coherence tomography. Of the 474 eyes studied, 137 and 337 were grouped into training and validation sets, respectively. The positions of the implanted IOLs of the training datasets were characterized with multiple linear regression analyses one month after the operations. A new regression formula was developed to predict the postoperative anterior chamber depth with the use of the stepwise analysis results. In the validation dataset, postoperative refractive values were calculated according to the paraxial ray tracing of the cornea and lens based on the assumption of finite structural thicknesses with separate surface curvatures. The predicted refraction error was calculated as the difference of the expected postoperative refraction from the spherical-equivalent objective refraction values. The percentage error (within ±0.50 diopters) of the new formula was 84.3%. This was not significantly correlated to the axial length or keratometry. The developed formula yielded excellent postoperative refraction predictions and could be applicable to eyes with abnormal proportions, such as steep or flat corneal curvatures and short and long axial lengths.

Relationship between Crystalline Lens Thickness and Shape and the Identification of Anterior Ocular Segment Parameters for Predicting the Intraocular Lens Position after Cataract Surgery.

PURPOSE: This study was performed to investigate the relationships among crystalline lens shape, actual intraocular lens (IOL) position, and crystalline lens thickness (LT), as measured by anterior segment optical coherence tomography (AS-OCT), and to determine anterior ocular segment parameters that predict postoperative IOL position. METHODS: Seventy-nine eyes of 79 patients who underwent uneventful cataract surgery were enrolled. For crystalline lens preoperative anterior segment data, the LT, and anterior, equatorial, and posterior surface depths (ASD, ESD, and PSD, respectively) of crystalline lenses were quantitatively determined. For postoperative anterior segment data, the actual IOL position was quantified. Moreover, the following correlations were analyzed: LT with the ASD, ESD, PSD, and IOL position; IOL position with the ASD, ESD, and PSD; and refractive prediction error with the difference between the predicted postoperative anterior chamber depth (ACD) of the SRK/T formula and the IOL position, ASD, ESD, and PSD (each depth minus the predicted postoperative ACD of the SRK/T formula). RESULTS: The LT was significantly correlated with the ASD (r = -0.65) and PSD (r = 0.41), whereas it was not correlated with the ESD or IOL position. The IOL position was significantly correlated with the ASD (r = 0.67), ESD (r = 0.72), and PSD (r = 0.74). The refractive prediction error was significantly correlated with the difference between the predicted postoperative ACD of the SRK/T formula and the IOL position (r = 0.65), ASD (r = 0.46), ESD (r = 0.54), and PSD (r = 0.58). CONCLUSIONS: The ESD and PSD obtained using AS-OCT were highly correlated with the IOL position and significantly correlated with the refractive prediction error. These findings suggest that the ESD and PSD may enhance the accuracy of actual IOL position prediction.

Biometry: a tool for the detection of amblyopia risk factor in children.

PURPOSE: To determine optical biometry data criteria for the detection of abnormal refraction in preschool children, and to evaluate the accuracy of these criteria for detecting amblyopia refractive risk factor (ARF), as defined in the 2013 guidelines of the American Association for Pediatric Ophthalmology and Strabismus (AAPOS). METHODS: The present study included 200 eyes of 100 preschool children with normal eyes for the experimental determination of criteria and 142 eyes of 71 preschool children for validation of these criteria. Statistical data from normal eyes were used to determine both "high sensitivity failure criterion" and "high specificity failure criterion" associated with corneal astigmatism, interocular difference in axial length, and the prediction interval of a regression formula for predicting corneal power from axial length. Ophthalmological examination of children for validation included testing cycloplegic refraction and optical biometry testing. Outcomes from optical biometry criteria were compared with determination via ophthalmological examination, and the accuracy of the criteria for detecting ARF was evaluated. RESULTS: Sensitivity of the "high sensitivity failure criterion" for detecting 2013 AAPOS ARF was 100%, while the specificity was 80.5%. The sensitivity of the "high specificity failure criterion" was 93.3%, while the specificity was 95.1%. CONCLUSIONS: The criteria derived from optical biometry data in this study exhibited excellent sensitivity and specificity for detecting ARF. This study may lead to a new approach to vision screening in preschool children.

The Repeatability of Values Measured Using the Spot Vision Screener in Healthy Children and Children with Refractive Errors.

Purpose: To determine the repeatability of refractive values measured using the Spot vision screener in healthy children and children with refractive errors. Methods: This cross-sectional study included 170 eyes of 85 healthy children (normal group), and 50 eyes of 25 children wearing spectacles for refractive errors (spectacles group). The spherical equivalent value, cylindrical value, and inter-ocular differences in the spherical equivalent values were analyzed. The repeatability of the refractive values measured using the Spot vision screener was determined using intra-class correlation coefficients (ICCs) and 95% limits of agreement. Results: In the normal group, ICC values for the spherical equivalent value, cylindrical value, and amount of anisometropia were 0.77, 0.80, and 0.64, respectively. In the spectacles group with spectacles they were 0.89, 0.67, and 0.78, respectively. In the spectacles group without spectacles they were 0.96, 0.78, and 0.97, respectively. The 95% limits of agreement between consecutive measurements for the spherical equivalent value, cylindrical value, and amount of anisometropia were within ±1.00 D in the normal group and the spectacles group with spectacles, and over ±1.00 D in the spectacles group without spectacles. Conclusions: The Spot vision screener can ensure better than moderate repeatability with and without spectacles.

Prediction of pupil size under binocular open-view settings using the new CASIA2 device.

PURPOSE: Pupillometry should be performed under conditions as close to natural viewing as possible. The present study aimed to determine whether pupil size in binocular open-view settings can be predicted based on pupil size measured using the CASIA2 device. METHODS: The present study included 61 participants (25 men and 36 women; mean age, 49 ± 15 years; age range, 22-69 years) with no history of ophthalmic disease other than refractive errors and cataract. We measured pupil size using the new CASIA2 device and a binocular open-view digital pupillometer (FP-10000II, TMI Co., Ltd., Saitama). Intra-class and inter-class reliabilities were evaluated by measuring pupil times three times with each device (two independent examiners) in 21 of the 61 participants. Reproducibility was analyzed using intra-class and inter-class correlation coefficients (ICCs). Regression formulae for calculating FP10000II pupil size based on CASIA2 pupil size were developed via simple linear regression analyses. RESULTS: Both devices exhibited high ICC values (> 0.80). The regression formulae for calculating the FP10000II pupil size for the distant and near views based on CASIA2 pupil size were y = 0.5702x + 0.4611 (determination coefficient, 0.67) and y = 0.502x + 0.445 (determination coefficient, 0.64), respectively. CONCLUSIONS: Pupil size under binocular open-view settings can be predicted based on simultaneous measurement of pupil size during evaluation of the anterior segment using the CASIA2 device. The calculated pupil size may represent a useful index for determining the most appropriate treatment strategy in candidates for cataract and refractive surgery.

Differences in the Stimulus Accommodative Convergence/Accommodation Ratio using Various Techniques and Accommodative Stimuli.

PURPOSE: To investigate differences in the stimulus accommodative convergence/accommodation (AC/A) ratio using various techniques and accommodative stimuli, and to describe a method for determining the stimulus AC/A ratio. METHODS: A total of 81 subjects with a mean age of 21 years (range, 20-23 years) were enrolled. The relationship between ocular deviation and accommodation was assessed using two methods. Ocular deviation was measured by varying the accommodative requirement using spherical plus/minus lenses to create an accommodative stimulus of 10.00 diopters (D) (in 1.00 D steps). Ocular deviation was assessed using the alternate prism cover test in method 1 at distance (5 m) and near (1/3 m), and the major amblyoscope in method 2. The stimulus AC/A ratios obtained using methods 1 and 2 were calculated and defined as the stimulus AC/A ratios with low and high accommodation, respectively, using the following analysis method. The former was calculated as the difference between the convergence response to an accommodative stimulus of 3 D and 0 D, divided by 3. The latter was calculated as the difference between the convergence response to a maximum (max) accommodative stimulus with distinct vision of the subject and an accommodative stimulus of max minus 3.00 D, divided by 3. RESULTS: The median stimulus AC/A ratio with low accommodation (1.0 Δ/D for method 1 at distance, 2.0 Δ/D for method 1 at near, and 2.7 Δ/D for method 2) differed significantly among the measurement methods (P < 0.01). Differences in the median stimulus AC/A ratio with high accommodation (4.0 Δ/D for method 1 at distance, 3.7 Δ/D for method 1 at near, and 4.7 Δ/D for method 2) between method 1 at distance and method 2 were statistically significant (P < 0.05), while method 1 at near was not significantly different compared with other methods. CONCLUSIONS: Differences in the stimulus AC/A ratio value were significant according to measurement technique and accommodative stimuli. However, differences caused by measurement technique may be reduced by using a high accommodative stimulus during measurements.

Evaluation of visual function in preschool-age children using a vision screening protocol.

PURPOSE: To evaluate the relationship between uncorrected visual acuity and refraction and binocular function using a vision screening protocol. METHODS: In total, 760 children (3-6 years old) who were enrolled in 4 nursery schools in Otawara, Japan, were recruited; a total of 1,520 eyes were examined. We assessed uncorrected near visual acuity, manifest refraction, stereopsis, and eye position. Subjects were divided into 4 subgroups according to the lowest uncorrected near visual acuity value compared between the 2 eyes: group 1 (visual acuity [VA] ≤0.00 [logarithm of the minimum angle of resolution]), group 2 (VA 0.15-0.05), group 3 (VA 0.52-0.22), and group 4 (VA >0.52). These parameters were compared among the groups. RESULTS: The sample number of each of the 4 sub-groups was as follows: group 1, 608; group 2, 114; group 3, 27; and group 4, 11. The median spherical equivalent values were -1.13 diopter (D) in group 1 and -1.00 in group 2, which were more myopic than group 4. Median cylindrical power in group 1 was 0.25 D, and was the lowest among all groups. In group 1, median anisometropia was 0.38 D and median corneal astigmatism value was 1.13 D; both values were lowest in group 1. With regard to binocular function, 89.6% of the subjects in group 1 had 60 arcseconds or better in near stereopsis and 98.8% had no detectable strabismus, which were significantly different from the findings in the other groups. The percentage of subjects in group 1 who had 80 arcseconds or worse in near stereopsis was 10.4%. In contrast, 90.9% of the subjects in group 4 had 80 arcseconds or worse in near stereopsis, and 18.2% had intermittent or manifest strabismus. CONCLUSION: We suggest that examination of refraction and stereopsis in preschool-age children undergoing vision screening is an important supplement to visual acuity testing.

Evaluation of Relative Afferent Pupillary Defect Using RAPDx Device in Patients with Optic Nerve Disease.

We previously reported the standard values of the amplitude and latency scores in the RAPDx device for evaluating relative afferent pupillary defect (RAPD). Here, we evaluated RAPD in patients with optic nerve disease by using these standard values. Twenty-eight patients with current or previous optic nerve disease were enrolled in this study. Additionally, the data of 84 healthy subjects from our previous report were used as control data. We measured the amplitude and latency scores using RAPDx. We then compared their mean values and the percentages of individuals with standard values within a certain range between the optic nerve disease group and healthy group. Additionally, we evaluated their correlation with visual acuity and the critical flicker fusion frequency in the optic nerve disease group. Both parameters were significantly higher in the optic nerve disease group than in the control group (p < 0.0001). The detection rate of RAPD when using the standard value of amplitude score was 75%. Additionally, both parameters showed a significant correlation with laterality-based differences in visual acuity and critical flicker fusion frequency values in the optic nerve disease group (r = 0.59-0.75, p < 0.001). The amplitude and latency scores determined using RAPDx are useful in evaluating RAPD, particularly the standard value of the amplitude score.

Evaluation of Sensory Dominance Using Binocular Rivalry as Related to Ocular Deviations.

INTRODUCTION AND PURPOSE: To investigate the relationship between sensory dominance and ocular deviations. PATIENTS AND METHODS: Sixty-three patients were evaluated with a new device for the measurement of exclusive visibility during binocular rivalry. The patients were consisted of twenty-three with exotropia (XT), twenty with intermittent exotropia [X(T)], twenty with exophoria (XP), respectively. Device is composed of two retinometers, their holders in which angle and position can be adjustable and a PC for data storage and analysis. In each of eyes, exclusive visibility of one stimulus during binocular rivalry was measured for 60 sec, and the strength of ocular dominance was evaluated by the difference of exclusive visibility between dominant and nondominant eye. RESULTS: The difference of exclusive visibility time between dominant and nondominant eye were 9.8±3.7 sec in the XT group, 6.1±4.1 sec in the X(T) group and 2.2±1.5 sec in the XP group, respectively. There were significant differences between XT and X(T) (P<0.01) as well as between XT and XP (P<0.001). CONCLUSIONS: The present result indicates that sensory dominance was obviously influenced by ocular deviations since exclusive visibility of dominant eye was prolonged with decreasing the opportunity of normal binocular vision such as XT or X(T).

Binocular function in patients with pseudophakic monovision.

PURPOSE: To evaluate the relationship between ocular deviation and stereopsis and fusion in patients who had pseudophakic monovision surgery. SETTING: Department of Ophthalmology, Kitasato University Hospital, Kanagawa, Japan. DESIGN: Retrospective comparative case series. METHODS: Patients had surgical monovision correction with monofocal intraocular lens placement followed by routine postoperative examinations. The alternate prism cover test was used to measure motor alignment. Sensory tests for binocularity included sensory fusion determinations using the Worth 4-dot test, near stereopsis test, and fusion amplitude measured with a prism bar. Patients with monovision were categorized as having small-angle exophoria (≤10.0 prism diopters [Δ]) or moderate-angle exophoria (>10.0 Δ). RESULTS: This study comprised 60 patients with a mean age of 70.2 years ± 7.7 (SD). The difference in the mean stereopsis values between patients with small-angle exophoria and patients with moderate-angle exophoria was statistically significant (P<.001). In the moderate-angle exophoria group, 10 patients (62.5%) developed intermittent exotropia after surgery; however, no serious ocular deviation problems were observed. The fusion amplitudes in patients with pseudophakic monovision were approximately similar to normal values. Patients with moderate-angle exophoria were more likely to fail the Worth 4-dot test than those with small-angle exophoria. CONCLUSIONS: In patients with pseudophakic monovision having a near exophoria angle of more than 10.0 Δ, the possibility of changes in ocular deviation and stereopsis after surgery is a concern. Moreover, the application of monovision in patients with a previous moderate-angle exophoria should be carefully considered. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Saccadic reaction times in alternating cover.

PURPOSE: The aim of this study was to compare saccadic reaction times (SRTs) during the alternating cover with SRTs during monocular viewing. METHODS: Seven subjects with intermittent exotropia, eight subjects with esophoria and ten control subjects were participated. The normal-task was to fixate the central fixation point until the peripheral target appeared randomly either 5 degrees to the right or left. In the alternating cover task (AC-task), the cover was switched from the fixating eye to the other eye, central fixation target was simultaneously extinguished and peripheral target was lit. An infrared limbal-tracking system and electro-oculogram were used for measurements of eye movements. The study followed the tenets of the Declaration of Helsinki. We certify that there is no conflict of interest. RESULTS: In AC-task, the average SRTs of control subjects, subjects with exophoria and subjects with intermittent exotropia were 224.2 ± 46.5 ms, 198.2 ± 45.3 ms and 227.3 ± 69.9 ms, respectively. On the other hand, the average SRTs of control subjects, subjects with exophoria and subjects with intermittent exotropia in normal-task were 200.7 ± 37.8 ms, 178.2 ± 34.6 ms and 185.4 ± 54.1 ms, respectively. CONCLUSIONS: The SRTs of most control subjects, subjects with exophoria and subjects with intermittent exotropia in AC-task were prolonged compared to normal-task.

Sensory adaptation in exophoria and exotropia.

INTRODUCTION AND PURPOSE: To investigate the effect of exodeviation in spatial visual attention using the illusory line motion paradigm. METHODS: The perception of visual illusion (i.e., illusory line motion) in the dominant and nondominant eyes was examined in 12 control subjects (under 5(Δ)), 12 exophoria patients (over 10(Δ)), and 12 exotropia patients. This paradigm presents two cues followed by an instantaneously presented horizontal bar, which the subjects perceive as bars that emanate from the two priming cues. These bars appear to grow toward the center of the visual field and continue to move inward until they collide with each other. In these experiments, the priming cues were asynchronously and simultaneously presented. RESULTS: In the dominant eye, there was no correlation between the collision point shift and the ocular deviation, regardless of the stimulus patterns. However, a correlation was noted between the collision point shift and the ocular deviation in the nondominant eye when the second cue was presented in the nasal hemi-retina (P < 0.01). The shift of the collision point in exophoria and exotropia was greater than that seen in the control subjects (P < 0.01). When there was simultaneous presentation of the two cues in the nasal and temporal hemi-retina, there was a difference in the shift of the collision point in the exotropia patients, as compared to both the control subjects and exophoria patients (P < 0.05). CONCLUSIONS: Current findings strongly suggest that sensory adaptation in the nondominant eye compensates for visual stress with ocular deviation.

[Assessment of visual function and satisfaction in pseudophakic monovision].

PURPOSE: To investigate the visual function and acceptability of pseudophakic monovision in relation to age. METHODS: We examined 82 cases (age: 49-87 years) with pseudophakic monovision. All cases were undergone monovision using monofocal intraocular lens (IOLs). The cases were classified into three groups based on their age (A, less than 60 years; B, between 60 to 70 years ; and C, more than 70 years). Refractive error, visual acuity at various distances, contrast sensitivity, and near stereopsis were measured. Using a questionnaire, patient satisfaction before and after cataract surgery was evaluated. RESULT: The mean difference in spherical equivalent refractive error between both eyes was 2.27 D (A, 2.39D; B, 2.30D; and C, 2.20 D). Most cases had a binocular uncorrected visual acuity of 20/25 or better at all distances. For contrast sensitivity, binocular summation was observed at 1.5 to 6 cycles/ degree. Near stereopsis was in the normal range, which was less than or equal to 100 seconds of arc. Moreover, it was found that 82% of the patients were satisfied with the results (A, 68%; B, 86%; and C, 93%). CONCLUSION: Pseudophakic monovision may be an effective approach for managing loss of accommodation after cataract surgery especially in patients over 60 years of age. However, careful selection of patients should be carried out.

[The influence of ocular dominance on monovision--the interaction between binocular visual functions and the state of dominant eye's correction].

PURPOSE: To examine the interaction between binocular visual functions and the correction of the dominant eye, i.e., for far vs. near vision in monovision. SUBJECTS AND METHODS: Ten healthy subjects without any ophthalmological disease were examined. After cycloplegia, the eyes of the subjects were corrected by soft contact lenses (difference in lens power between the lenses: 2.5 D) with an artificial pupil(diameter: 3.0 mm). Visual acuity at various distances, contrast sensitivity, and near stereoacuity were measured while the dominant eye determined by the hole-in-card test (sighting dominance) was corrected for far and near vision. RESULTS: Binocular visual acuity was better than 1.0(20/20) at all distances. When the dominant eye was corrected for distance, the binocular visual acuity at 0.7 m was better than the monocular visual acuity; contrast sensitivity was better within the spatial frequency range of 0.5-4.0 cycles per degree, and near stereoacuity by Titmus stereo tests improved. CONCLUSION: These results suggest that dominant eyes should be corrected for far vision for better binocular summation at middle distances, and near stereoacuity.

[The influence of ocular dominance on monovision--the influence of strength of ocular dominance on visual functions].

PURPOSE: Monovision is a method of correction for presbyopia. We have reported the advantage of conventional monovision (the dominant eye is corrected for distance). In this study, we investigated the influence of interocular imbalance of dominancy on the visual function. SUBJECTS AND METHODS: Ten healthy subjects without any ophthalmologic disease participated. After cycloplegia, the eyes of the subjects were corrected by soft contact lenses with an artificial pupil (diameter: 3.0mm). The dominant eye was corrected for distance, and the difference in lens power between the lenses was 2.5 D. The subjects were classified into two groups by strength of the imbalance of sensory dominance, which was determined by using binocular rivalry. Binocular visual functions (visual acuity at various distances, contrast sensitivity, near stereoacuity) were compared between the two groups. RESULTS: Subjects with strong imbalance of sensory dominance showed decreased near visual acuity as well as decreased binocular summation of contrast sensitivity at low spatial frequencies. On the other hand, near stereoacuity was not affected by the imbalance of sensory dominance. CONCLUSION: These results suggest that strong imbalance of sensory dominance interferes with binocular visual functions in monovision. Thus, the evaluation of ocular dominance is crucial for clinical applications of monovision.

Effects of dominant and nondominant eyes in binocular rivalry.

PURPOSE: To investigate the relation between sighting and sensory eye dominance and attempt to quantitatively examine eye dominance using a balance technique based on binocular rivalry. METHODS: The durations of exclusive visibility of the dominant and nondominant eye target in binocular rivalry were measured in 14 subjects. The dominant eye was determined by using the hole-in-card test (sighting dominance). In study 1, contrast of the target in one eye was fixed at 100% and contrast of the target in the other eye was varied from 100% to 80% to 60% to 40% to 20%, when using rectangular gratings of 1, 2, and 4 cycles per degree (cpd) at 2 degrees, 4 degrees , and 8 degrees in size. In study 2, contrast of the target in the nondominant eye was fixed at 100% and contrast of the target in the dominant eye was varied from 100% to 80% to 60% to 40% to 20%, when using a rectangular grating of 2 cpd at 4 degrees in size. RESULTS: In study 1, the total duration of exclusive visibilities of the dominant eye target; that is, the target seen by the eye that had sighting dominance was longer compared with that of the nondominant eye target. When using rectangular gratings of 4 cpd, mean total duration of exclusive visibility of the dominant eye target was statistically longer than that of the nondominant eye target (p < 0.05). In study 2, reversals (in which duration of exclusive visibility of the nondominant eye becomes longer than the dominant eye when the contrast of the dominant eye target is decreased) were observed for all contrasts except for 100%. CONCLUSIONS: The dominant sighting eye identified by the hole-in-card test coincided with the dominant eye as determined by binocular rivalry. The contrast at which reversal occurs indicates the balance point of dominance and seems to be a useful quantitative indicator of eye dominance to clinical applications.