Tomoya Handa

Ocular dominance and patient satisfaction after monovision induced by intraocular lens implantation.

Purpose: To elucidate the relationship between ocular dominance and patient satisfaction with monovision induced by intraocular lens implantation. Setting: Eye Clinic, Kitasato University School of Medicine Hospital, Sagamihara, Kanagawa, Japan. Methods: The durations of exclusive visibility of dominant‐ and nondominant‐eye targets were measured in 16 patients with successful monovision and 4 patients with unsuccessful monovision to determine the characteristics of ocular dominance. The dominant eye was determined using the hole‐in‐card test (sighting dominance). The contrast of target in nondominant eye was fixed at 100%; the contrast of target in the dominant eye varied (ie, 100% to 80% to 60% to 40% to 20%) using rectangular gratings of 2 cycles per degree that were 4 degrees in size. Results: In the successful monovision group, the reversal thresholds (ie, exclusive visibility of the nondominant eye crosses over that of the dominant eye) were displayed only at low decreasing contrast (80% and 60%). However, in the unsuccessful monovision group, the reversal thresholds were at high decreasing contrast (20%) or not at all. The reversal thresholds in patients with unsuccessful monovision were at a significantly lower contrast than in patients with successful monovision (P<.05). Conclusions: Success and patient satisfaction in monovision patients were significantly influenced by the magnitude of ocular dominance. The balance technique seems to be a good method to evaluate the quantity of ocular dominance and prospectively evaluate the monovision technique.

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°, 4°, and 8° 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° 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.

Assessment of visual performance in pseudophakic monovision

PURPOSE: To assess the visual performance and acceptability of pseudophakic monovision and examine its relationship to age. SETTING: Department of Ophthalmology, Kitasato University Hospital, Kanagawa, Japan. METHODS: This retrospective study examined patients with pseudophakic monovision using monofocal intraocular lenses. Refractive errors, visual acuity at various distances, contrast sensitivity, and near stereopsis were measured. Patient satisfaction with monovision was evaluated using a questionnaire. RESULTS: Eighty‐two patients (age 49 to 87 years) were evaluated. The mean difference in spherical equivalent refractive error between each patients eyes was 2.27 diopters. Most patients had a binocular uncorrected visual acuity of 0.10 logMAR or better at all distances. For contrast sensitivity, binocular summation was observed at 1.5 to 6.0 cycles per degree. Near stereopsis was in the normal range, which was up to 100 seconds of arc. Questionnaire responses showed that 81% of patients (64% <60 years; 87% between 60 years and 70 years; 94% older than 70 years) were satisfied with the results. CONCLUSION: Pseudophakic monovision was an effective approach for managing loss of accommodation after cataract surgery in patients older than 60 years; however, a careful selection process is required.

Diurnal variation of human corneal curvature in young adults.

PURPOSE To elucidate the diurnal variation of human corneal curvature with regard to gender and menstrual cycle. METHODS Changes in corneal curvature and intraocular pressure (IOP) were measured over 24 hours in 14 young adults using corneal topography and a non-contact tonometer. In study 1, seven males and seven females (after menses) were measured. In study 2, four females out of the seven volunteers who participated in study 1 were measured again during menses. RESULTS The females after menses showed a remarkable diurnal variation throughout 24 hours. A significant difference between the light-wake periods and dark-sleep periods of 0.83 +/- 0.15 D was found (P < .01). Corneal curvature was significantly flatter during menses than after menses in the light-wake period (P < .05). In the males, no significant diurnal change (0.21 +/- 0.12 D) was measured in corneal curvature. CONCLUSIONS Diurnal variation of corneal curvature was significant, approximately 0.83 D in young females after menses, and corneal curvature became flatter during menses in young females. Diurnal variation of corneal curvature is an important parameter for planning refractive surgery and contact lens wear.

Quantitative measurement of ocular dominance using binocular rivalry induced by retinometers

PURPOSE: To develop a new method using binocular rivalry and retinometers to quantitatively examine ocular dominance and to investigate the magnitude of ocular dominance in cataract patients preoperatively and postoperatively. SETTING: Eye Clinic, Kitasato University School of Medicine Hospital, Sagamihara, Kanagawa, Japan. METHODS: The duration of exclusive visibility of the dominant and nondominant eye target in binocular rivalry were measured in 60 healthy volunteers (study 1) and preoperatively and postoperatively in 10 cataract patients (study 2). Rivalry targets were presented directly to the retina of each eye using 2 retinometers. Subjects reported the exclusive visibility of 1 eye target, and the total duration of exclusive visibility for each eye in dominant and nondominant eye trials was evaluated. RESULTS: In study 1, the magnitude of ocular dominance was quantitatively assessed with 4 grades based on differences in total duration of exclusive visibility between dominant and nondominant eyes. In study 2, magnitude of ocular dominance could be evaluated in all cataract patients regardless of refractive and cataract conditions. Magnitude of ocular dominance displayed significant correlations between preoperative and postoperative conditions (simple regression, P<.001). CONCLUSIONS: Ocular dominance can be quantitatively evaluated using this new method based on binocular rivalry and retinometers, particularly in cataract patients. Magnitude of ocular dominance may indicate preoperatively whether a patient with cataracts will have sufficient ocular dominance to adjust to monovision correction.

Effects of ocular dominance on binocular summation after monocular reading adds

PURPOSE: To investigate the relationship between ocular dominance and binocular summation with monocular reading adds. SETTING: Department of Orthoptics and Visual Science, School of Allied Health Sciences, Kitasato University, Sagamihara, Kanagawa, Japan. METHODS: Contrast sensitivities were measured by having subjects view contrast charts at spatial frequencies of 1.5, 3.0, 6.0, 12.0, and 18.0 cycles per degree after the addition of positive spherical lenses that ranged from +1.0 to +3.0 diopters (D). Through the use of a balance technique, the test group was quantitatively divided into 12 weak and 8 strong ocular dominance subjects on the basis of binocular rivalry. In study 1, binocular contrast sensitivity was measured in the weak and strong ocular dominances by adding a positive spherical lens in front of 1 eye, whereas the other eye was fixed at a corrected distance. RESULTS: In study 1, the binocular summation was observed only after adding positive spherical lenses in the nondominant eye. The differences in binocular contrast sensitivity that occurred after adding a positive spherical lens in the dominant eye versus that seen in the nondominant eye were statistically significant in the strong ocular dominance subjects who had +1.5 D and +2.0 D defocuses (P<.05; analysis of variance). CONCLUSIONS: Binocular summation was effectively maintained with reading adds in the nondominant eye and was significantly influenced by the magnitude of ocular dominance. Evaluating binocular summation after monocular reading adds seems to be a good method to evaluate adaptability to monovision.

A New Method for Quantifying Ocular Dominance Using the Balancing Technique

Introduction and Purpose To develop a chart for the clinical setting that can quantify ocular dominance by using the modified balancing technique, a method based on binocular rivalry. Methods In 100 healthy young volunteers, rightward-tilted and leftward-tilted square-wave gratings were presented to the right and left eye, respectively. A newly designed chart employing balancing techniques based on binocular rivalry was used in conjunction with a viewer. Target contrast in the nondominant eyes was fixed at 100%, while in the dominant eyes it was varied from 100% to 10% during ten steps that used a square-wave grating of 2 cycles per degree and which were 4° in size. By varying the contrast of the dominant eye, a “reversal point,” which is where the exclusive visibility time or the conscious perception frequency of the nondominant eye exceeds the dominant eye, is revealed. This can be used to assess the magnitude of the ocular dominance. Results Ocular dominance magnitude results indicated there was a good correlation between the modified and original balancing techniques. The modified balancing technique also showed high measurement repeatability. Conclusions A chart that uses the modified balancing technique for ocular dominance examinations can be used as a simple test to quantify ocular dominance within clinical settings.

Effect of pupil size on visual acuity in a laboratory model of pseudophakic monovision.

PURPOSE To investigate the effect of pupil size on visual acuity in pseudophakic monovision. METHODS For the simulation, a modified Liou-Brennan model eye was used. The model eye was designed to include a centered optical system, corneal asphericity, an iris pupil, a Stiles-Crawford effect, an intraocular lens, and chromatic aberration. Calculation of the modulation transfer function (MTF) was performed with ZEMAX software. Visual acuity was estimated from the MTF and the retinal threshold curve. The sizes of the entrance pupil were 2.0, 2.5, 3.0, and 4.0 mm. RESULTS Decreasing pupil diameter and increasing myopia progressively improved near visual acuity. For an entrance pupil size of 2.5 mm and a refractive error of -1.50 diopters, the logMAR value (Snellen; metric) in the non-dominant eye at 40 cm was 0.06 (20/23; 6/6.9). CONCLUSIONS Knowledge of the patients pupil diameter at near fixation can assist surgeons in determining the optimum degree of myopia for successful monovision.

Comparison of Subjective Refraction under Binocular and Monocular Conditions in Myopic Subjects.

To compare subjective refraction under binocular and monocular conditions, and to investigate the clinical factors affecting the difference in spherical refraction between the two conditions. We examined thirty eyes of 30 healthy subjects. Binocular and monocular refraction without cycloplegia was measured through circular polarizing lenses in both eyes, using the Landolt-C chart of the 3D visual function trainer-ORTe. Stepwise multiple regression analysis was used to assess the relations among several pairs of variables and the difference in spherical refraction in binocular and monocular conditions. Subjective spherical refraction in the monocular condition was significantly more myopic than that in the binocular condition (p < 0.001), whereas no significant differences were seen in subjective cylindrical refraction (p = 0.99). The explanatory variable relevant to the difference in spherical refraction between binocular and monocular conditions was the binocular spherical refraction (p = 0.032, partial regression coefficient B = 0.029) (adjusted R2 = 0.230). No significant correlation was seen with other clinical factors. Subjective spherical refraction in the monocular condition was significantly more myopic than that in the binocular condition. Eyes with higher degrees of myopia are more predisposed to show the large difference in spherical refraction between these two conditions.

Effects of pupil dilation on objective refraction

Editor, R efractive correction, including glasses, contact lenses or refractive surgery, is common procedure in modern clinical ophthalmology practice. However, frequent sequela of refractive correction is refractive error, which greatly affects the patient’s quality of vision. Improving the accuracy of the preand postexamination is important in minimizing refractive error. In the refraction test, we inspect one eye while covering the other eye. However, this test differs from the everyday visual environment, in which both eyes are kept open. Although it has been reported that the pupil dilates when one eye is covered (Kawamorita & Uozato 2014), it has not yet been reported how this affects visual function. In this study, we investigated the effects of pupil dilation on objective refraction. This study included 30 healthy volunteers with a mean age of 20.5 1.5 years. We certify that all applicable institutional regulations concerning the ethical use of human volunteers were followed. We used a binocular open auto ref/keratometer (WAM-5500; Grand Seiko, Ltd., Fukuyama City, Hiroshima Prefecture, Japan) to measure the chronological change in pupil diameter and objective refraction associated with covering one eye. We had patients fixated on an angular vision visual acuity chart (0.1) at a distance of 5 m. We measured, in order, binocular (15 s), monocular (30 s, using an occluder) and binocular (15 s) vision (Fig. 1A). Statistical analysis was performed using the Scheff e test, with values of P < 0.01 considered to be significant. The chronological changes in pupil diameter and objective refraction associated with covering one eye are shown in Fig. 1B. When one eye was covered, the pupil slowly dilated. The average pupil diameter before, during and after covering was 4.32 0.013 mm, 5.25 0.26 mm and 4.14 0.26 mm, respectively. The pupil diameter was significantly larger with one eye covered than it was before (P = 0.0002) and after covering (P = 0.0008). There was no significant difference in the pupil diameter measurements taken before and after covering (P = 0.94). The average objective refraction before, during and after covering was 2.18 0.07 diopters (D), 2.32 0.09 D and 2.22 0.09 D, respectively. The objective refraction with one eye covered was significantly myopic compared with before (P = 0.0003) and after (P = 0.0018) covering, with differences of 0.14 D (maximum, 0.57 D) and 0.10 D (maximum, 0.51 D), respectively. There was no significant difference in the objective refraction measurements taken before and after covering (P = 0.90). When one eye was covered, the pupil dilated. As a result, the objective refraction became myopic. The depth of focus decreased because of pupil dilation, and the retinal image became blurred (Campbell 1957). It has been shown that the retinal image blurs in response to accommodation (Kaufman & Alm 2003); it is assumed that accommodation causes the retinal image to blur. Our results suggest that covering one eye causes refractive error after refractive correction. As our study was to investigate chronological changes of objective refraction and pupil diameter, we could not conduct it (A)