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PubMed1986

Cone function and cone interaction in hereditary degenerations of the central retina.

Spectral sensitivity functions and the transient decrease of sensitivity to short wavelengths after the offset of yellow light (transient tritanopia) were measured by increment threshold techniques in patients suffering from hereditary macular degenerations. Color vision defects were determined by arrangement tests and the anomaloscope. Central areolar choroidal dystrophy was found to produce a mild protan defect and to reduce foveal spectral sensitivity throughout the visible spectrum by a factor of 100; it also abolishes transient tritanopia. Electroretinogram (ERG) was normal, electrooculogram (EOG) subnormal. Stargardt's disease, despite numerous fluorescent macular spots, does not abolish transient tritanopia nor does it reduce spectral sensitivity, although scotopic matches were performed on the Nagel anomaloscope. Only in severe, advanced cases was transient tritanopia reduced and spectral sensitivity found to follow the absorption spectrum of rods. Routine ERGs and EOGs were normal. Vitelliform macular degeneration, despite the ophthalmoscopically pronounced dystrophic macula, produced only very small changes in spectral sensitivity and transient tritanopia, although a widened matching range on the Nagel anomaloscope and electrophysiological abnormalities were found. Apparently damage of the retinal circuit which connects long and short wavelength-sensitive cones, caused by hereditary conditions, is different from that caused by retinotoxic drugs.

Adult↗
PubMed1991

Difficulty differentiating Leber's from dominant optic neuropathy in a patient with remote visual loss.

A 31-year-old man who inexplicably lost vision as a child was referred for evaluation of bilateral optic atrophy. Other family members had also suffered unexplained visual loss. He had asymmetric impairment of visual acuity, central scotomas, and optic disc pallor. He also had a tritan color vision defect and excavation of the temporal portion of his optic discs, two features that were consistent with autosomal dominant optic atrophy. However, examination of the mitochondrial DNA of the proband and of two of his relatives revealed a mutation at nucleotide 11778, known to be associated with Leber's hereditary optic neuropathy. This case illustrates the difficulty physicians may encounter when trying to clinically differentiate Leber's from dominant optic atrophy in patients with remote visual loss, and it emphasizes the importance of obtaining a molecular assay for a mitochondrial mutation in cases of ambiguously classified hereditary optic neuropathy.

Adult↗
PubMed1990

Distinguishing between clinical impairments due to optic nerve or macular disease.

Many optic neuropathies and subtle maculopathies may have similar clinical presentations. This represents a challenge to the ophthalmologist to distinguish between the two on clinical grounds. These patients may not have obvious signs and their symptoms may be ambiguous. For example, a young man presenting with optic neuritis may have similar complaints to one suffering from central serous retinopathy. Several general principles can be used to distinguish between optic neuropathies and maculopathies. Additionally, specific psychophysical tests can be of help. The most important aspect of the history is in establishing the tempo of onset, duration and resolution of the symptoms. Optic nerve lesions often produce symptoms described as dimness or grayness, whereas macular lesions usually reduce visual acuity and produce metamorphopsia. The clinical examination requires comparing optic nerve function studies (afferent pupillary defects, color vision and brightness sense) to visual acuity. Additionally, assessing the central visual field especially through Amsler grid testing or threshold Amsler grid testing is very useful. Certain psychophysical tests can be performed in the office. Threshold amsler grid testing, photostress testing, contrast sensitivity, and the Pulfrich phenomena can all be put to advantage in distinguishing between optic neuropathies and maculopathies.

Diagnosis, Differential↗
PubMed1987

Ability of deutan color defectives to perform simulated air traffic control tasks.

Air traffic controllers perform a variety of tasks which require them to identify, discriminate, and name colors. Qualification standards for this occupation require applicants and incumbents to have normal color vision. The validity of this standard has been questioned and is currently under review. In this study, 22 deutans and 78 normals were tested on a set of tasks which simulated critical tasks performed daily by air traffic controllers. The four tasks included discriminating red from black pencil marks on flight progress strips, color-naming of 1 degree and 0.1 degree discs, and identification of colored line segments embedded in a multicolored background. Deutans classified as mild were found to perform all tasks as well as normals. Moderate deutans performed only the large disc color-naming task as well as normals, whereas severe deutans performed none of the tasks as well as normals. Different methods for scoring the color vision tests were explored to determine their value as predictors of task performance. The D-15 relative error score was found to be the single best predictor of performance on the tasks (r-square = 0.602). It is concluded that mild deutan color defectives have adequate color vision for safe performance of several critical air traffic control tasks. Moderate and severe deutans do not. In addition, the results of several methods for scoring color vision tests can be used to predict group, but not individual, performance with high reliability.

Aviation↗
PubMed1988

A new perimetric color vision analyzer.

A new apparatus was developed for mapping the extrafoveal color vision, the perimetric color vision analyzer. A yellow test object with varying degrees of saturation is presented on a cathode ray tube color display in a random sequence at one of 10 points around the fixation spot. The background is a mosaic pattern consisting of gray spots of the same size and shape as the test object, with various luminances. Background patterns with or without a test object are presented alternately. The subject is instructed to press a key when he detects a yellow object in the background pattern. The luminance of the test object is in the same range as the background gray spots. Since the luminance of background spots is changed synchronously at random when the test object appears, the subject can detect the test object only by the difference in color saturation. The results show the color contrast sensitivity at every designated point in the central visual field. The clinical application of the perimetric color vision analyzer revealed extrafoveal color defects which could not be evaluated with conventional color vision tests. It also showed that in some chorioretinal and optic nerve disorders the topographic pattern of color contrast sensitivity disagrees with that of luminance contrast sensitivity measured with automated static perimetry.

Adult↗
PubMed1992

Vision defects in albinism.

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.

Adolescent↗
PubMed1979

The ability of color defectives to judge signal lights at sea.

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.

Color Vision Defects↗
PubMed1989

[Screening of early color vision loss in diabetic patients].

Colour vision defects have been claimed to appear in diabetes before any retinopathy is visible. In the present study diabetic patients and non diabetic control subjects were screened with two different colour vision tests which include both red-green and blue-yellow parts, and are suitable for quantitative analysis of scores. The Lanthony 40 Hue test and the Tokyo Medical College--T.M.C. tables were used to assess colour vision in 106 diabetic (50 insulin dependent and 56 non insulin dependent) patients and in 99 non diabetic control subjects. Diabetic patients without visible retinopathy, familiar colour vision defects and/or lens changes, had significantly higher scores than control subjects in both eyes. The differences were more evident in non insulin dependent patients. Statistical analysis showed that early loss of colour vision was correlated with age and duration of diabetes for older patients, while correlation with glycosylated hemoglobin was moderately positive only for younger patients. Both tests (especially the Lanthony 40 Hue) resulted to be highly specific and could be used for the clinical study of colour vision losses in diabetic patients.

Adult↗