Fumiko Matsumoto

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.

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.

Quantification of Eccentric Fixation Using Spectral-Domain Optical Coherence Tomography

Purpose: This study aimed to evaluate the utility of optical coherence tomography (OCT) in the quantification of eccentric fixation in amblyopic patients. Material and Methods: In this study, 14 amblyopic patients and 10 healthy volunteers were enrolled. Under non-mydriatic conditions, fixation tests were performed directly using a fixation ophthalmoscope and indirectly using spectral-domain OCT. For evaluations using OCT, the distance between the fovea and the fixation point, which was determined by a cross-sectional image, was measured. Results: On evaluations of healthy volunteers by OCT, the mean distance between the fixation point and the fovea was 80.4 ± 37.7 μm for the dominant eyes and 63.7 ± 36.4 μm for non-dominant eyes (p = 0.41). In amblyopic patients, on evaluation by OCT, the mean distance between the fixation point and the fovea was 193.8 ± 188.3 μm in amblyopic eyes and 83.5 ± 39.3 μm in paired fellow eyes (p = 0.02). Although OCT could detect eccentric fixation points in all the affected eyes of amblyopic patients, fixation ophthalmoscope was unable to quantify them in 2 of 14 affected eyes. Conclusions: Compared with a fixation ophthalmoscope, our method using OCT seems to be superior both in quantification and detection of eccentric fixation in amblyopic patients, without the need for mydriasis.

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.

Effects of Progressive Additional Lenses on Binocular Vision in Children with Pseudophakia

Binocular vision may be compromised in children after unilateral cataract surgery because the distances at which clear vision is present are different for the two eyes. We believe that wearing progressive additional lenses can be effective in improving the binocular vision in children with pseudophakia.