A new visual pigment model to account for colour vision defect.
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We have examined the possible presence of color vision anomalies in 9 individuals (17 eyes, 1 blind) with fundus findings suggesting ocular albinism using the Ishihara plates, the 28-hue Roth test, and the Davico anomaloscope. Results indicate that four of these individuals show no sign of the anomalies expected in an albino in either of the two eyes. Of the remaining cases, two are simple deuteranomals in both eyes, according to Pickford's classification criteria. The rest have protanomaly; however, in these the deviation toward red appears in both eyes in only one subject, whereas in the other two subjects it appears in only one eye, their binocular color vision being basically normal. Our study shows that a large proportion of these albinos have photophobia, pendular nystagmus, strabismus, noticeable refractive errors (astigmatism and high myopia), and poor visual acuity [usually less than 6/30 (20/100) with correction]. The measurement of contrast sensitivity function (CSF) indicates that the frequency of 12 cpd cannot be perceived, even in binocular vision.
Measures were made of the ability of color-defective men to judge correctly the colors of navigation lights (red, green, or white) presented to them at night under realistic sea conditions. Eighty-one color-defective men were employed; they were categorized as to type and degree of defect using a battery of five color-vision tests. While the average performance of the color-defective men was considerably poorer than that of 24 color normals, there were large individual differences within each category of defect. Attempts to account for these differences in performance by variations in acuity, intelligence, and motivation failed. The extent to which the data can be accounted for by modern color-vision theory is discussed.
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Extensive copper infiltration of Descemet membrane of the central cornea and of the anterior and posterior surfaces of the lens is associated with marked hypercupremia related to an abnormal immunoglobulin. Observation of this spectrum of ophthalmic changes in an apparently well middle-aged woman heralded the diagnosis of a unique variety of multiple myeloma.
The Davidson and Hemmendinger (DH) color rule was evaluated for color vision screening of normal and congenital color-defective subjects. Ninety-eight normal and 14 color-defective subjects were tested on the color rule under Macbeth illumination of 5,400 K. The color-defective subjects were also tested on the Nagel anomaloscope, the Farnsworth D-15, and the H-R-R pseudoisochromatic plates. The DH color rule performed as accurately as the anomaloscope and was superior to the other two tests in detecting anomalous trichromats and in discriminating protanomalous subjects. The color rule also discriminated dichromats from anomalous trichromats. For severe color-defective subjects (dichromats, achromats), the color rule was more time-consuming than the other tests and discrimination was less certain. Response patterns on the DH color rule and response variability of the different classifications are reported.
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A red contact lens (X-Chrom lens) worn on the nondominant eye by 12 color-defective subjects caused significant improvements on the Dvorine, Ishihara, and Hardy-Rand-Rittler pseudo-isochromatic color plate tests. Color vision scores on the Farnsworth Lantern, Color Threshold Tester, and Aviation Signal Light Gun were not improved. Minimal changes were found on the Farnsworth D-15 test, aeronautical chart color identification task, visual acuity, phoria, and stereoscopic depth perception. Control and color-defective subjects perceived a change in the path of a pendulum (Pulfrich test) when viewing through the X-Chrom lens or a monocular red filter. The X-Chrom lens may require extended wearing before its optimum effect becomes apparent.
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A genealogical link was established six generations back between a family living in England and Australia, and one of the families reported originally by Sorsby et al (1949) as suffering from autosomal dominant inflammatory macular dystrophy (fundus dystrophy). The onset--in the fifth decade of life--and the progress of the condition, which usually ends in blindness, has been observed in a number of patients and the prodromal development of a colour vision deficiency in some of them confirmed. This defect is fundamentally different from the X-linked colour vision defects and merits further investigation.
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