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Purpose: For the purpose of classification for social adaptability of color vision defectiveness, the Farnsworth Dichotomous Test D-15(Test D-15)was applied to distinguish a severe group from other cases. Following this, the Ichikawa Lantern was employed to separate a moderate from a mild group. Majima's classification has provided a convenient framework for identifying color vision defectiveness for the past several decades. However because of the discontinuity in the employment of Ichikawa's Lantern, the introduction of alternative methods is vital. New classification methods subdividing the "moderate/mild" group into separate groups were established by using simulations. Subjects and methods: Simulations of hue discrimination using the color caps of Test D-15 were carried out. Adding color caps one by one between each of the 15 color test caps of Test D-15 to a total of 30, or subtracting caps from Test D-15 to nine (P-1-3-5-7-9-11-13-15)or six(P-2-5-8-11-14) were employed to simulate the compressing of the hue circles along the color confusion lines. Simulations changing the saturation of color caps were conducted simultaneously. Results: The fewer the number of caps, the more errors occurred. Subtracting the number of caps of Test D-15 made it possible to subdivide the "moderate/mild" group into three groups. Changing the saturation of color caps of Test D-15 had no effect on the results of the Test D-15. Conclusion: Using Test D-15 and reducing the number of caps to nine or six allows for the identification of different levels of color defectiveness and the assigning of patients into separate groups.

Purpose: To compare the sensitivity of hyperacuity of cyclovertical deviated patients with that of normal subjects., Subjects and Methods: The sensitivity of hyperacuity was measured in 42 normal and 12 cyclovertical deviated patients, using a newly developed computerized device which randomly presents two targets opposed vertically or horizontally on a cathode ray tube(CRT) display., Results: In normal subjects, lower thresholds were obtained when the targets were aligned either vertically or horizontally. These highly sensitive ranges were defined as "the neutral zone of hyperacuity". An anisotropy of the sensitivity of hyperacuity was observed. i.e., better thresholds were obtained when the offset was set away from the neutral zone, whereas worse thresholds were obtained when the offset as close to the neutral zones. In cyclovertical deviated patients, the thresholds of hyperacuity were high around the neutral zones, which may indicate dysfunction of the central nervous system., Conclusion: This analytical method may be useful to investigate the pathophysiology of the patients with cyclovertical deviations.

The receptive field center of double flash resolution (DFR) and of critical flicker fusion frequency (CFF) in a 3 degrees temporal visual field were examined in 11 normal subjects and 19 glaucoma and ocular hypertension patients. In normal subjects, the mean receptive field center of DFR was 2.17 log min of arc2 and that of CFF was 2.55 log min of arc2. In many glaucoma and ocular hypertension cases, the receptive field center of DFR (mean:2.48 log min of arc2) was significantly enlarged and came close to that of CFF (mean:2.53 log min of arc2)(p < 0.01). Although these findings were mostly seen in patients with some visual field changes, they were also encountered in 9 (70%) of the 13 cases with ocular hypertension without any visual field changes and are probably related to poor intraocular pressure control. We considered that the result was due to the dysfunction of the surrounding area of DFR that consists of interaction between sustained and transient functions of the visual pathway. This dysfunction could be closely related to the disorder of alpha-cells that occurs in the early stage of glaucoma.

Double flash resolution (DFR) and critical flicker fusion frequency (CFF) at the center of the visual field and the 5 degrees superior visual field were measured in normal subjects as a function of the stimulus area. Six stimulus sizes, ranging from a visual angle of 5' to 3 degrees 36' were used. The following results were obtained. First, the CFF increased as the stimulus area became larger at both the center and the 5 degrees superior visual field. Secondly, at the center of the visual field, the DFR initially increased as the stimulus area became larger and then decreased. Thirdly, at the 5 degrees superior visual field, this inhibitory phenomenon was also encountered with great individual variations and was not so evident as at the center of the visual field. Fourthly, the increasing rate of sensitivity was found to be greater at the 5 degrees superior visual field than at the center of the visual field in both CFF and DFR. From these results, we speculated that the CFF was detected by the transient system, which exhibited a weaker or no surround inhibition, and that the DFR in the center of the visual field was detected by the sustained system, which exhibited great surround inhibition. The DFR at the 5 degrees superior visual field could be detected by both transient and sustained systems.