Akemi Wakayama

Influence of target size and eccentricity on binocular summation of reaction time in kinetic perimetry

To assess how target size and eccentricity affect binocular summation (BS) of reaction time (RT) at suprathreshold level, we measured RT using targets of 0.108° and 0.216° at four eccentricities (0°, 5°, 15°, 25°) in six normal volunteers. The difference between the monocular/binocular RT differentials for both sizes significantly increased in the periphery (P<0.05). The smaller target required significantly longer monocular RT at 25° (P<0.01) and generated greater neural summation than the larger target (P<0.01). This suggests that when monocular function has reached its limit in visual processing in the periphery, BS increases, facilitates visual processing, and shortens binocular RT.

Properties of receptive field on binocular fusion stimulation in the central visual field.

AbstractBackground. Visual information projected onto corresponding points on the right and left retinas converges on the binocular cells in the visual cortex. The aim of this study is to investigative the characteristics of the receptive field for binocular stimulation in the central visual field of normal-sighted human subjects. Methods. We investigated the receptive field for binocular stimulation under fusion conditions by combining the Octopus 201 with the space synoptophore. We measured binocular and monocular sensitivities while the fusion patterns were projected onto the Octopus 201 cupola, using the space synoptophore. We designed a new program to test 37 points in the central 6° visual field. Six target sizes were tested: the white-spot targets of 0.054°, 0.108°, 0.216°, 0.431°, 0.862° and 1.724° projected diameters. Results. The threshold energy necessary for binocular stimulation was lower than that for the monocular stimulation in all subjects. This difference was more obvious on the test points that were more distant from the fovea when target sizes of 0.054° and 0.108° were used. The amount of binocular summation ratio was highest for target size 0.054° in each stimulus area in the central 6° of the visual field. When we measured binocular summation using target sizes larger than 0.108°, the result was the constant summation. Conclusions. The size of the receptive field for binocular stimulation is smaller than monocular stimulation under the same fusion condition. The amount of binocular summation varies as a function of target size.

Influence of Background Complexity on Visual Sensitivity and Binocular Summation Using Patterns with and without Noise

PURPOSE To investigate how background complexity influences visual sensitivity and binocular summation. METHODS Using two noise backgrounds (noise-sparse and noise-dense) and two corresponding noise-free backgrounds with the same luminance for each noise background, monocular and binocular thresholds were measured in six visually normal subjects (average age, 27.3 ± 1.1 years). The noise-sparse and noise-dense backgrounds respectively had 312 and 936 white-light dots projected on them-the same size white-light dots (0.431° of visual angle) as those that were used for the white-spot target in the threshold measurement. The target was tested at the fovea and at 3° intervals on the 45°, 135°, 225°, and 315° meridians. A total of 25 locations were tested. RESULTS The monocular threshold for the noise-dense background was higher than that for its corresponding noise-free background, with significant differences seen at 15° and 18° (P < 0.01). No significant differences in the binocular threshold were seen, either between the noise-dense and its corresponding backgrounds or between the noise-sparse and its corresponding backgrounds. The binocular summation ratios for both noise backgrounds were significantly higher than the ratios for the noise-free backgrounds, and the difference increased with eccentricity, with significances seen at 15° and 18° (P < 0.01). CONCLUSIONS Only the monocular threshold increases with background complexity. The binocular summation increases with background complexity in the periphery. When the background becomes more complex and the monocular visual processing reaches its limit, binocular interaction functions efficiently.

Effect of stimulus size on binocular summation within the binocular visual field

PURPOSE To study the influence of stimulus sizes on binocular summation using the modified Octopus 201 combined with a space synoptophore. METHODS Four normal subjects, aged 21 to 26 were tested. Using the SARGON program, we designed a new program to test 37 points in the central 6 degrees visual field. Sensitivity of the central 6 degrees visual field under monocular and binocular conditions was measured while the fusion patterns were displayed on the space synoptophore. The visual fields were measured at stimulus sizes 1, 3, and 5. RESULTS The visual sensitivity under binocular conditions was higher than under monocular conditions for all the stimulus sizes. Binocular summation for stimulus size 1 was present in a flat form, for stimulus size 3 in a convex form, and for stimulus size 5 in a concave form in the central 6 degrees visual field. CONCLUSION Binocular summation differed in stimulus size and retinal eccentricity. Binocular summation for stimulus size 3 increased in the fovea and it increased for stimulus size 5 in the peripheral area in the central 6 degrees visual field.

Incidence of side effects of topical atropine sulfate and cyclopentolate hydrochloride for cycloplegia in Japanese children: a multicenter study

PurposeTo investigate the incidence rate and side effects of topical atropine sulfate and cyclopentolate hydrochloride for cycloplegia in children aged 15 years or under.MethodsThis prospective study had been conducted at 9 institutions between April 1, 2016 and March 31, 2017 in patients 15 years old or younger who received either atropine or cyclopentolate for refraction assessment. The investigation included patient’s age, symptoms, and whether patients with side effects had any systemic diseases.ResultsA total of 811 patients (mean age ± SD, 4.6 ± 2.2 years) received atropine and 71 (8.8%) patients had side effects. Except in patients under two years old, 1% eye drops showed higher incidence rate of side effects than 0.5% and 0.25% eye drops. Side effects most frequently occurred following the initiation of the instillation on the first day. The symptoms included flush (29/71, 40.8%), fever (21/71, 30.0%), and both (11/71, 15.5%). A total of 2238 patients (5.7 ± 3.0 years) used cyclopentolate and 27 (1.2%) (4.0 ± 2.2 years) patients had side effects. The symptoms included drowsiness (10/27, 37.0%), red eye (4/27, 14.8%), fever (3/27, 11.1%), and flush (3/27, 11.1%).ConclusionsAtropine has a side effect incidence rate 7 times higher than the incidence rate of cyclopentolate. Flush and fever are the most common side effects of atropine and drowsiness is the main side effect of cyclopentolate. These findings should be noted when examining cycloplegic refraction to manage amblyopia and strabismus in children.

Role of fusional convergence amplitude in postoperative phoria maintenance in children with intermittent exotropia

PurposeTo examine the role of fusional convergence amplitude in postoperative phoria maintenance in childhood intermittent exotropia [X(T)].MethodsThe medical records of 29 children aged 15 years or younger (mean age, 10.8 ± 2.4 years) and treated with monocular recession-resection for X(T) were reviewed retrospectively. The patients’ fusional convergence amplitude (break point/total amplitudes), physiologic diplopia, and phoria maintenance (presence/absence of phoria maintenance and ability to maintain phoria) were assessed. The presence of phoria maintenance was confirmed by a cover test, and the ability to maintain phoria was quantified using the Bagolini red filter bar. Correlations of the amplitude size with the presence and ability of phoria maintenance were investigated.ResultsA significant correlation was seen between fusional amplitude (break point/total) and ability to maintain phoria at near and at far (break point: P < .05 at near/P < .01 at far; total: P < .05 at near/far). Neither the break point amplitude nor the total amplitude significantly differed between the patients with phoria maintenance and those without it (break point: P = .71 at near, P = .29 at far; total: P = .98 at near, P = .85 at far). Phoria maintenance correlated with the suppression of physiologic diplopia during phoria (P < .01). The deviation angle did not significantly correlate with fusional amplitude either at near (P = .58) or at far (P = .27).ConclusionsIn childhood X(T), fusional amplitude plays a role in enforcing the patient’s ability to maintain phoria. However, sufficient fusional amplitude does not guarantee fully functioning fusion if suppression is present during phoria.

Influence of Test Distance on Stereoacuity in Intermittent Exotropia

ABSTRACT Aims: To investigate influence of test distance on stereoacuity in intermittent exotropia (X[T]) using the same test conditions for both near and far distances. Methods: Subjects were 38 consecutive patients with X(T). All the patients were between ages 6 and 15 years and had decimal visual acuity of 1.0 or better. Another inclusion criterion was presence of phoric condition at near and far distances. Stereoacuity was measured at a near distance of 40 cm and at a far distance of 5 m. The following test conditions were used for both test distances: separation of the two eyes using polarized glasses, and a target with a random dot pattern. All the stereograms had the same subtended angle of 2.5º, and binocular disparity of 480, 240, 120, and 60 arcsec. We used two stereogram types with crossed and uncrossed disparities. Results: Far stereoacuity of 38 subjects measured with the crossed disparity was significantly worse than near stereoacuity (P<0.05, Wilcoxon signed-ranks test), although 30 (78.9%) of the 38 subjects showed no differences in stereopsis between the near and far distances. Far stereoacuity of 38 cases measured with the uncrossed disparity was significantly worse than at near (P<0.05, Wilcoxon signed-ranks test), although 20 (52.6%) of the 38 subjects showed no differences between stereoacuity at near and far. In comparison of stereoacuity with crossed disparity and uncrossed disparity, stereoacuity with crossed disparity was significantly better than that with uncrossed disparity both at near and far (P<0.05, Wilcoxon signed-ranks test). Conclusions: Stereoacuity in X(T) was different according to test distance when measured controlling subtended angle of stereogram at both distances. Far stereoacuity was significantly worse than near stereoacuity when measured using test targets with both crossed and uncrossed disparities. Additionally, stereoacuity measured with crossed disparity was better than that with uncrossed disparity at both distances.