Number and variations of the red and green visual pigment genes in Japanese men with normal color vision.

PURPOSE: We analyzed the red/green visual pigment genes in color-normal Japanese men to understand the relationship between color anomalies and genetic defects. METHODS: DNA from 120 color-normal Japanese men was subjected to polymerase chain reaction (PCR)-amplification for exons 2-5 of the red/green visual pigment genes and the PCR products were sequenced. The red:green gene ratios were estimated from the sequencing electropherograms of exon 5 and also from MvaI-restriction fragment analysis of the same exon. The first gene and the downstream genes in the pigment gene array were separately analyzed by PCR, direct sequencing, and/or single-strand conformation polymorphisms. RESULTS: The red:green gene ratios estimated from the ratios of peak heights of nucleotides on the sequencing electropherograms coincided with those estimated from the MvaI-restriction fragment analysis. Among the subjects analyzed, they were 1:1 in 43% (n = 52), 1:2 in 41% (n = 49), 1:3 in 6% (n = 7), and 1:>3 in 9% (n = 11). The first gene in the pigment gene arrays was red in all subjects. Only 1 subject (N22) had a green-red hybrid gene. Exons 2 and 4 had 2 haplotypes each, but exon 3 was highly polymorphic. Exon 5 of the green genes had one polymorphism at codon 283 with a frequency of 32%. CONCLUSIONS: The features of visual pigment genes in color-normal Japanese men were revealed. The data and establishing techniques may be useful for analyzing these genes in color-deficient subjects in the Japanese population.

Detection of female carriers of congenital color-vision deficiencies by visual pigment gene analysis.

PURPOSE: Congenital color-vision deficiencies are frequent among males, 4.7-8.0%, suggesting that female carriers are present at a frequency of 9-15%. The purpose of this study was to determine whether carriers could be detected by analysis of the visual pigment genes. METHODS: DNA from 29 males with congenital color-vision deficiencies, from their mothers, and from 117 randomly-selected females was analyzed. The most upstream genes, the downstream genes, and the most downstream genes in the red/green pigment gene arrays were amplified separately by PCR. Exon 5 of each gene was analyzed by single-strand conformation polymorphisms (SSCP). RESULTS: Analysis of the visual pigment genes suggests that one of the 29 mothers examined is a female protan and two others are carriers of both protan and deutan defects. The remaining 26 mothers were confirmed to be carriers of congenital color-vision deficiencies. Unusual patterns were observed in 15 (13%) of the randomly-selected females; among them, 5 appeared to be protan carriers and at least 4 to be deutan carriers. CONCLUSIONS: Female carriers of congenital color-vision deficiencies can be detected by analysis of the visual pigment genes. Since the proportion of females showing unusual patterns was slightly higher than expected, some must be false-positives and require more detailed examination.

Temporal integration in diseased eyes.

We examined critical duration for visual acuity in eyes with central serous retinopathy (CSR), macular edema (ME) and glaucoma. Critical duration for visual acuity is the minimum period of time to perceive the acuity chart of his best. Visual acuity was measured at several limited exposure durations and the results were then compared with that of normal eyes. The acuity target was a single Landolt ring. The size, direction, and exposure duration of the target were computer controlled. The mean critical duration for visual acuity of the CSR and ME groups was 1.78 s and 2.69 s. These were significantly longer than that of the normal group (0.62 s). The critical duration of the glaucoma group was 0.42 s, which was not significantly prolonged. Critical duration for the increment or static threshold was measured for the purpose of comparison, and no significant differences were found between the diseased eyes (the CSR and ME groups) and the normal eyes, although the thresholds were significantly higher in the diseased eyes. Next, fixation movements which occurred during visual acuity testing were observed in order to investigate their role in acuity testing. In both normal and ME eyes the frequency and amplitude of microsaccades were smaller while the visual acity chart was shown. This suggests that microsaccades play no positive role in the reading of acuity charts, and that they bear little relation to the phenomenon of critical duration for visual acuity. From these results we hypothesized that in the CSR and ME groups the X-type ganglion cells send incomplete information to the central neural system. Thus, a longer time is required to obtain complete information before responding. Furthermore, one glaucoma case suggested that in diseased eyes in which mainly the Y-cell systems are damaged, temporal specificity in visual acuity for shorter exposure duration may reveal different response patterns.

[Correlation of the grade of nuclear and cortical cataract, visual acuity, and contrast sensitivity].

A correlative investigation of 125 eyes with senile cataractous lenses was conducted to determine the relationships between cortical (CC) and nuclear cataracts (NC), corrected visual acuity (VA), and contrast sensitivity (CS). The CS for the spatial frequency of 1.5 cycles/degree (c/d) and 12.0 c/d was analyzed in particular detail. The results were as follows: (1) CC and CS for both 1.5 and 12.0 c/d showed statistically significant negative correlations with a coefficient (CE) of -0.250 and -0.288 respectively. No correlation was found between CC and VA. (2) NC and VA showed a significant negative correlation with CE of -2.29. No correlation was found between NC and CS for at 1.5 and 12.0 c/d. (3) VA and CS showed a significant positive correlation with a CE of +0.436 at 1.5 c/d and +0.270 at 12.0 c/d. The CS at 1.5 and the CS at 12.0 c/d also showed a significant negative correlation with a CE of +0.477. (4) NC and CC showed a significantly negative correlation (r = -0.224, p < 0.01), suggesting that scattered light from the nucleus may be interfered with by cortical opacities during slitlamp examinations. (5) In 29 cases of no cortical opacity, nuclear opacity showed significant negative correlation with VA (r = 0.556 p < 0.01) but no significant correlation with CS of both 1.5 and 12 c/d. (6) In 30 cases with less than 0.085 of nuclear opacity, cortical opacity showed significant negative correlation with CS at 12.0 c/d (r = 0.364 p < 0.01) but showed no significant correlation with VA and CS at 1.5 c/d.

[Temporal integration in diseased eyes. III. Fixation movements in visual acuity testing].

The fixation movements which occur during visual acuity testing were observed in order to clarify the mechanism behind the critical duration in visual acuity testing, which we found in a previous study to be significantly longer in central serous retinopathy and macular edema. Photoelectric oculography (p-EOG) was used to record horizontal eye movement in this study. In normal eyes the frequency and amplitude of the microsaccades were smaller while the acuity target was shown than when it was not shown. This phenomenon was also observed in eyes with macular edema. These results suggest that microsaccades play no positive role in the reading of visual acuity targets, and that they bear little relation to the phenomenon of critical duration in visual acuity testing.

[Temporal integration in diseased eyes. I. Exposure duration in visual acuity testing].

Critical duration in visual acuity testing can be viewed as an expression of temporal integration in the human visual system. We examined this phenomenon in 13 eyes with central serous retinopathy (CSR) and 6 eyes with macular edema, by measuring visual acuity at several limited exposure times. The results were then compared with those for 17 normal eyes. The acuity target was a single Landolt ring projected upon a small square screen. The size, direction, and exposure time of the target were computer controlled. The mean critical durations of the CSR and macular edema groups were 1.78 sec. and 2.69 sec. respectively. These values were significantly (p less than 0.01) longer than the mean critical duration of the normal control group (0.62 sec.). Although the mechanism behind the longer critical duration in diseased eyes remains poorly understood, we believe this method provides a possible approach to the study of diseased visual conditions.

Comparison of two fast quantitative methods for evaluating the Stiles-Crawford function.

Stiles-Crawford (SCE) functions are determined using an increment threshold procedure. The customary technique requires considerable time to obtain a full SCE function and in many situations, both clinical and experimental, it is imperative that the SCE function be evaluated at many retinal loci in as short a time as possible. We have been using two different variants of the standard method, one requiring a very limited number of threshold settings at five fixed entry points in the entrance pupil (5-point method) and in the other, thresholds are determined at only three preselected entry points (3-point method). The time required to obtain a complete SCE function is the order of 5 to 8 min using either method. Comparison and statistical evaluation of the techniques are presented.

Effect of monocular light exclusion on the Stiles-Crawford function.

Contrary to previously published studies, monocular light exclusion did not alter the shape of the Stiles-Crawford function in a substantial manner in four subjects who were patched in this laboratory for one full week. In order to rule out methodological differences, an experimenter from each of the two sets of experiments (current and prior) patched one eye for 1 week, then tested each other. For one subject, there was little effect of patching. For the other, patching had a measurable effect, but it was different from that originally reported. However, the much larger, symmetrical broadening of the Stiles-Crawford function reported in earlier studies was not replicated. A testable working hypothesis to explain the earlier results is discussed.

The Stiles-Crawford effect of the first kind (SCE I): studies of SCE I in an aniridic observer.

The Stiles-Crawford effect of the first kind (SCE I), discovered in 1933, represented a major breakthrough in our understanding of retinal physiology and the modern beginning of the science of photoreceptor optics. The current status of knowledge in this area is briefly reviewed. A study is presented of a white adult female observer with aniridia, clear media, only traces of nystagmus, rather good visual acuity, and good fixation. It is shown that this individual exhibits approximate alignment of her photoreceptors with the center of the retinal sphere, clear evidence of side lobes on functions, and surprisingly steep SCE I functions. The implications of these findings are considered.

Contrast (modulation) sensitivity functions measured in patients with high refractive error with emphasis on aphakia: II. Determinations of patients.

Measurements of Constrast Sensitivity Functions (CSF) were made on normal observers made artificially highly ametropic with spectacle lenses (with high back vertex) distance in order to determine the effect of retinal image size alterations upon CSF measures. While not an exact model for high ametropia per se, this experiment served to familiarize the experimenters with problems associated with the task. Image size alterations occur normally in aphakic patients and highly myopic patients. As a clinical trial, a series of aphakic observers were tested using an interferometric acuity device. CSF measures were made with the patient's spectacle corrections in place and again with correcting contact lenses substituted. The contact lenses reduce induced image size alterations in these cases. The use of contact lenses in such measures allows differentiation between artifactual low frequency fall off in aphakia due to lens effects and possible low frequency fall-off due to other causes.

Malignant melanoma of the lacrimal sac.

A case of malignant melanoma of the lacrimal sac in a 41-year-old woman is reported, which is propably the 12th one in the world literature. Dacryocystectomy is advisable at a localized stage. The importance of early diagnosis is discussed.