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PubMed1992

Visual dysfunction without retinitis in patients with acquired immunodeficiency syndrome.

Patients with human immunodeficiency virus infection may have noninfectious and infectious retinopathies, as well as clinical symptoms consistent with optic nerve dysfunction. Noninfectious acquired immunodeficiency syndrome-related retinopathy is seen in most patients with AIDS. Morphologic studies have shown that the number of retrobulbar optic nerve fibers in patients with AIDS is decreased compared to the number of optic nerve fibers in normal control eyes. To determine whether these patients had a visual dysfunction consistent with damage to the macula and optic nerve, 78 subjects (156 eyes) were studied using color-vision and contrast-sensitivity testing. The Farnsworth-Munsell 100-Hue color-vision test was performed on all subjects and age-corrected color-vision scores for all groups were compared. A significant decrease in color discrimination was found in the patients with AIDS (P less than .001). Contrast-sensitivity testing disclosed a deficit of contrast threshold in patients with AIDS at four of five spatial frequencies and in patients with AIDS-related complex at three of the five spatial frequencies examined. This study demonstrated a functional visual deficit in eyes without retinitis consistent with dysfunction of the macula or optic nerve in patients with AIDS.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Variety of genotypes in males diagnosed as dichromatic on a conventional clinical anomaloscope.

The hypothesis that dichromatic behavior on a clinical anomaloscope can be explained by the complement and arrangement of the long- (L) and middle-wavelength (M) pigment genes was tested. It was predicted that dichromacy is associated with an X-chromosome pigment gene array capable of producing only a single functional pigment type. The simplest case of this is when deletion has left only a single X-chromosome pigment gene. The production of a single L or M pigment type can also result from rearrangements in which multiple genes remain. Often, only the two genes at the 5' end of the array are expressed; thus, dichromacy is also predicted to occur if one of these is defective or encodes a defective pigment, or if both of them encode pigments with identical spectral sensitivities. Subjects were 128 males who accepted the full range of admixtures of the two primary lights as matching the comparison light on a Neitz or Nagel anomaloscope. Strikingly, examination of the L and M pigment genes revealed a potential cause for a color-vision defect in all 128 dichromats. This indicates that the major component of color-vision deficiency could be attributed to alterations of the pigment genes or their regulatory regions in all cases, and the variety of gene arrangements associated with dichromacy is cataloged here. However, a fraction of the dichromats (17 out of 128; 13%) had genes predicted to encode pigments that would result in two populations of cones with different spectral sensitivities. Nine of the 17 were predicted to have two pigments with slightly different spectral peaks (usually < or = 2.5 nm) and eight had genes which specified pigments identical in peak absorption, but different in amino acid positions previously associated with optical density differences. In other subjects, reported previously, the same small spectral differences were associated with anomalous trichromacy rather than dichromacy. It appears that when the spectral difference specified by the genes is very small, the amount of residual red-green color vision measured varies; some individuals test as dichromats, others test as anomalous trichromats. The discrepancy is probably partly attributable to testing method differences and partly to a difference in performance not perception, but it seems there must also be cases in which other factors, for example, cone ratio, contribute to a person's ability to extract a color signal from a small spectral difference.

Amino Acid Sequence↗
PubMed1998

Evaluation of ocular safety: tirapazamine plus cisplatin in patients with metastatic melanomas.

Ninety-six patients with metastatic melanoma treated with two consecutive tirapazamine-cisplatin combination chemotherapy regimens were followed for signs of therapy-related ocular toxicity. Baseline and follow-up data were obtained such that each patient acted as his own control. A battery of vision-related tests was performed. These included: best corrected visual acuity, color vision, retinal fundus examination and electro-oculograms (EOG). A brief health-related quality of vision test was administered at each follow-up visit to detect and evaluate self-perceived changes in visual status. In the first study, 48 patients received i.v. tirapazamine over 2 h at 260 mg/m2 (group 1) while in the second study 48 patients (group 2) received i.v. tirapazamine at 390 mg/m2. Visual system assessment was conducted at three timepoints: first at baseline, then at 6 weeks post-baseline, i.e. after two courses of chemotherapy and visit two upon discontinuation of therapy. There was no difference in visual acuity between group 1 and group 2 at baseline, follow-up 1 or at follow-up 2. Grouped data indicate that visual acuity was not affected by either dosage of chemotherapy. Group 1 at baseline found 15% below the normal EOG cutoff point, increasing to 23% at follow-up 1 and increasing at follow-up visit 2 to 33%. Group 2 demonstrated the same EOG findings, but the results were more magnified: baseline, 24%; follow-up 1, 44%; and follow-up 2, 44%. After eliminating those with abnormal color vision baselines, 21% (nine of 42) group 1 patients demonstrated abnormal color vision total error scores at follow-up 1 and 16.7% (four of 24) at follow-up 2. Few individuals showed changes in the higher dosage group. With the exception of one person in each dosage group, all changes were along the blue-yellow (tritan) axis, which is associated with acquired color defects. Of 96 patients examined, proven fundus changes were found in only four subjects. These fundus findings included retinal hemorrhages, retinal nerve fiber layer infarcts (cotton wool spots) and small retinal pigment epithelium detachments. There was no systematic statistical significant difference among the various measures of visual system outcome between groups or test times. Data from all tests for individual patients in both groups reveals a sporadic distribution of changes in visual system tests. If toxicity were pronounced, one would expect consistency in the findings and all or most of the assessment tests would be abnormal for a particular patient. However, patients who were abnormal on one measure of acuity were not necessarily abnormal on the other measures.

Adult↗
PubMed1992

Selective expression of human X chromosome-linked green opsin genes.

The human red and green photopigments are specified by genes on the long arm of the X chromosome (Xq28). In individuals with normal color vision, the locus was proposed to consist of a single red pigment gene upstream of one or more copies of green pigment genes. The presence of a single red pigment gene in the array was confirmed by demonstration of only one retinal mRNA transcript coding for the red opsin. In individuals with multiple green pigment genes, it is unknown whether all genes are expressed. We analyzed the sequence of red- and green-specific mRNA from retinas of individuals with multiple green pigment genes in comparison with the corresponding genomic DNA sequences. The data showed that only a single green pigment gene is expressed. We therefore suggest that a locus control-like element, already known to be located 3.8 kilobases upstream of the transcription initiation site of the red pigment gene, allows transcription of only a single copy of the green pigment genes, probably the most proximal copy. This finding provides an explanation for the not-infrequent presence of 5' green-red hybrid genes in individuals with normal color vision. Such hybrid genes are usually associated with defective color vision. We suggest that 5' green-red hybrid genes produce defective color vision only when their position in the gene array allows expression in the retinal cone cells.

Alleles↗
PubMed1998

Seeing beyond retinopathy in diabetes: electrophysiological and psychophysical abnormalities and alterations in vision.

Contrast sensitivity testing, in common with color vision (another test of psychophysical function), demonstrates significant changes in diabetic subjects compared with nondiabetic controls, and there is some evidence for a relationship with grade of retinopathy. Changes in contrast sensitivity have been demonstrated in children and adults with diabetes of short duration, and some evidence exists for a correlation with poor glycemic control, although prospective studies are required to assess this relationship over a longer time period. Although both color vision and contrast sensitivity demonstrate similar patterns, studies that directly compare the two tests suggest that measurement of contrast sensitivity is the more sensitive and specific.

Adult↗
PubMed2000

Visual function loss from vigabatrin: effect of stopping the drug.

OBJECTIVE: To determine if visual function loss from vigabatrin use recovers after the drug is discontinued. BACKGROUND: Vigabatrin is an effective antiepileptic drug, but it is known to cause a variety of changes in visual function, including reductions in the visual field, visual acuity, color vision, and in electroretinogram (ERG) and electro-oculogram amplitudes. It is not known whether these changes are reversible. METHODS: Measurements of static and kinetic visual fields, visual acuity, color vision, and the ERG were recorded while patients were taking vigabatrin and again in 13 patients who had discontinued the drug because of lack of efficacy or reductions in visual field. Most of the patients had been off the drug for 3 to 6 months, although two patients had been drug-free for almost 1 year. RESULTS: Although ERG cone implicit time improved, most of the patients did not show improvement in either clinical measures of visual function (i.e., visual acuity, color vision, visual fields) or in ERG amplitudes. However, several patients who showed minimal visual field loss while on the drug had substantial recovery of ERG amplitudes. There was no statistical association between recovery of function and either duration of treatment or cumulative dosage. The multifocal ERG showed a diffuse loss of function that was not isolated to the periphery. CONCLUSIONS: Although the visual deficits in patients taking vigabatrin tend to be mild, most patients do not show improvement after they stop taking the drug. Visual field loss resulting from vigabatrin was not reversible. Visual acuity, color vision, and ERG amplitude loss may be reversible in patients with minimal or no field loss.

Adult↗
PubMed1997

Cone and rod function in cone degenerations.

Progressive cone dystrophy (CD) is usually marked in the initial stages by reduced visual acuity, color vision deficiency and alterations in the photopic electroretinogram, while morphological alterations can be very mild; in some forms rods are affected in a later stage as well. We examined 40 patients with progressive cone dystrophy to determine the extent of functional losses in the cone system with psychophysical tests. A great variety of visual acuity and fundus alterations was found. Myopia was present in 74% of the patients. An autosomal dominant pattern of inheritance predominated (32%). No prevalence of gender was found. The age of onset ranged between 10 and 30 yr. All patients had progression of their symptoms. The total error score in color arrangement tests, the saturated Farnsworth Panel D-15 and the Farnsworth-Munsell 100-hue test, was pathologic with a predominance of confusions along the tritan and scotopic axis. Especially if visual acuity was below 0.5, color vision defects increased, but color vision defects were also found in patients with normal visual acuity. A general decrease of sensitivity in all three cone mechanisms was observed in measurements of spectral sensitivity. Moreover, cone-cone interaction as tested by transient tritanopia measurements was usually disturbed. In the dark adaptation function the threshold of the cone branch was usually elevated. These tests provide a good means to ascertain the correct diagnosis in early stages of the disease and to monitor progression in patients suffering from cone dystrophy.

Adolescent↗
PubMed1997

["Oligocone" trichromasy, a rare form of incomplete achromatopsia].

PATIENTS AND METHODS: An 11-year-old girl presented because of reduced visual acuity while color vision was almost normal. Besides a general ophthalmological examination, special psychophysical tests, such as perimetry, color vision tests using pseudoisochromatic plates, arrangement tests, the Nagel anomaloscope and spectral sensitivity measurement, and electrophysiological tests (electroretinogram and electrooculogram) were conducted. RESULTS: The tests yielded the following: congenital nystagm, normal results at ophthalmoscopy, best visual acuity of 0.1 monocular and 0.2 binocular. Perimetry revealed a relatively central scotoma. All color vision tests showed only mild dysfunction of the blue-sensitive cones. Findings at photopic electroretinogram were almost completely lacking. There was no sign of progression in the last 6 years. CONCLUSION: Differential diagnosis includes all diseases associated with congenital nystagm, such as aniridia, diseases of the optic nerve, albinism and all forms of hereditary cone dysfunction, cone dystrophies and complete and incomplete congenital stationary monochromatism. In the present case the findings are most congruent with oligocone trichromasy.

Child↗
PubMed2004

Corresponding-pair procedure: a new approach to simulation of dichromatic color perception.

The dichromatic color appearance of a chromatic stimulus T can be described if a stimulus S is found that verifies that a normal observer experiences the same sensation viewing S as a dichromat viewing T. If dichromatic and normal versions of the same color vision model are available, S can be computed by applying the inverse of the normal model to the descriptors of T obtained with the dichromatic model. We give analytical form to this algorithm, which we call the corresponding-pair procedure. The analytical form highlights the requisites that a color vision model must verify for this procedure to be used. To show the capabilities of the method, we apply the algorithm to different color vision models that verify such requisites. This algorithm avoids the need to introduce empirical information alien to the color model used, as was the case with previous methods. The relative simplicity of the procedure and its generality makes the prediction of dichromatic color appearance an additional test of the validity of color vision models.

Journal Article↗
PubMed2004

[Clinical advantages of colorimetric exploration in the early diagnosis of glaucomatous neuropathy].

AIM: The purpose of this investigation was to evaluate acquired color vision defects in the early stages of primary glaucoma and in patients at risk for glaucoma. MATERIAL AND METHODS: Patients with primary open-angle glaucoma, normal-tension glaucoma and ocular hypertension were examined with the IF-2 anomaloscope. The Rayleigh equation and the Moreland equation were tested. We studied the relationships between color vision defects and the other tested variables. RESULTS: We found the mean value of the setting range of the Moreland equation significantly increased in all tested groups. Color vision disturbances were found in 57% of eyes with glaucoma and in 31% of eyes with ocular hypertension. We found a positive correlation between the blue-green colour vision defects and the perimetric changes in the glaucomatous eyes. These results indicate a decrease in color discriminating sensitivity in the short wavelength part of the visible spectrum in patients with glaucoma as well as in patients with ocular hypertension. CONCLUSION: Blue-yellow color vision testing with the anomaloscope may serve as an additional test in the early diagnosis of glaucoma but the absence of dyschromatopsia does not exclude the disease.

Adult↗
PubMed2005

Evaluation of the new web-based "Colour Assessment and Diagnosis" test.

PURPOSE: The purpose of the study was to determine the sensitivity, specificity, and repeatability of the web-based Colour Assessment and Diagnosis (CAD) test in comparison to current tests of color vision. METHODS: Thirty color normals and 30 color deficients, identified and diagnosed by the Nagel anomaloscope, were tested. The results of the CAD test were compared with standard tests like Nagel anomaloscope, Ishihara (concise version, 2001), Hardy, Rand and Rittler (HRR; 4 ed) pseudoisochromatic test, and the Farnsworth Munsell 100 (FM-100) hue test. RESULTS: Using the Nagel anomaloscope as the "gold standard," the sensitivity with the CAD test was 93.33%, Ishihara 96%, HRR 100%, and the FM-100 hue 100%. The specificity was 100% with CAD and the Ishihara color plates, whereas it was 33% with the HRR and 83% with the FM-100 hue test. The concurrent validity of the CAD test for color normals was 93.75%. The concurrent validity of CAD test for color deficiency was 100%. Thus, anyone failing the CAD test has a color defect. The coefficient of agreement for the Nagel anomaloscope and the CAD test was 0.93, with Ishihara it was 0.96, with the HRR it was 0.33, and with FM-100 hue it was 0.83. CONCLUSION: These results showed that the CAD test is a valid test for identifying congenital red-green color deficiency. Further testing is required in a larger population of anomalous trichromats.

Adult↗
PubMed1997

Acquired dyschromatopsia in combined exposure to solvents and alcohol.

HYPOTHESIS: Does occupational exposure to solvents in combination with alcohol intake give rise to acquired color vision defects? METHOD: A total of 138 individuals exposed to solvents (toluene, xylene, trichloroethylene, tetrachloroethylene) were examined using Lanthony's D-15 test and compared with 100 nonexposed controls. The extent of color vision loss was quantitatively assessed based on Bowman's color confusion index (CCI). A cumulative exposure index was calculated from the hours of exposure per day and the years of exposure. In 30 persons who were exposed to trichloroethylene and tetrachloroethylene, urinary trichloroacetic acid was assessed as a parameter of exposure. Alcohol intake was calculated as based on interviews of patients in grams of ethyl alcohol per week. RESULTS: Individuals who consumed more than 250 g alcohol/week and were simultaneously exposed to solvents showed a significantly elevated CCI (P = 0.0044). No significant correlation emerged between trichloroacetic acid excretion in the urine or the cumulative exposure index and the CCI. CONCLUSION: The combination of alcohol intake and occupational exposure to solvents discloses the risk of acquired subclinical color vision defects.

Adult↗
PubMed1981

[Ocular side effects of digitalis (author's transl)].

In the Federal Republic of Germany nearly 4 million patients receive cardiac glycosides. Intoxication rates of up to 20% have been reported. About 80% of digoxin-intoxicated patients show generalized color vision deficiencies. Ophthalmologists should pay more attention to color vision disturbances due to digitalis.

Color Vision Defects↗
PubMed2006

Crepuscular and nocturnal illumination and its effects on color perception by the nocturnal hawkmoth Deilephila elpenor.

Recent studies have shown that certain nocturnal insect and vertebrate species have true color vision under nocturnal illumination. Thus, their vision is potentially affected by changes in the spectral quality of twilight and nocturnal illumination, due to the presence or absence of the moon, artificial light pollution and other factors. We investigated this in the following manner. First we measured the spectral irradiance (from 300 to 700 nm) during the day, sunset, twilight, full moon, new moon, and in the presence of high levels of light pollution. The spectra were then converted to both human-based chromaticities and to relative quantum catches for the nocturnal hawkmoth Deilephila elpenor, which has color vision. The reflectance spectra of various flowers and leaves and the red hindwings of D. elpenor were also converted to chromaticities and relative quantum catches. Finally, the achromatic and chromatic contrasts (with and without von Kries color constancy) of the flowers and hindwings against a leaf background were determined under the various lighting environments. The twilight and nocturnal illuminants were substantially different from each other, resulting in significantly different contrasts. The addition of von Kries color constancy significantly reduced the effect of changing illuminants on chromatic contrast, suggesting that, even in this light-limited environment, the ability of color vision to provide reliable signals under changing illuminants may offset the concurrent threefold decrease in sensitivity and spatial resolution. Given this, color vision may be more common in crepuscular and nocturnal species than previously considered.

Animals↗
PubMed2002

Screening for hydroxychloroquine toxicity by Texas ophthalmologists.

OBJECTIVE: To determine current practice patterns for screening for hydroxychloroquine (HCQ) toxicity by Texas ophthalmologists. METHODS: A survey was sent to all comprehensive ophthalmologists and retina specialists in the state of Texas. Questions included need for baseline examinations, frequency of followup, tests used to monitor for toxicity, and influences on monitoring regimen. RESULTS: Two hundred ninety of 577 surveys were returned correctly completed (response rate = 50.3%). Two hundred fifty-seven respondents (88.6%) felt a baseline examination was necessary prior to beginning HCQ therapy, and 223 (76.9%) followed patients every 6 months during HCQ therapy. Visual acuity, slit lamp examination, and dilated fundus examination were performed on almost all patients, and about three-quarters of respondents also checked visual fields and color vision. While 183 ophthalmologists (63.1%) used the Ishihara pseudoisochromatic plates to check color vision, there was no consensus on the preferred visual field test. One hundred twenty-two respondents (42.1%) stated they had diagnosed a patient with HCQ ocular toxicity. CONCLUSION: Most ophthalmologists in Texas continue to perform baseline examinations and follow HCQ patients semiannually for the development of ocular toxicity despite recent recommendations questioning the need for such close followup. The majority check visual acuity, perform slit lamp and dilated fundus examinations, and test color vision and visual fields, although there is no consensus on the preferred method to test visual fields.

Antirheumatic Agents↗
PubMed1988

Central serous chorioretinopathy in U.S. Air Force aviators: a review.

Idiopathic central serous chorioretinopathy (ICSC) is an uncommon disease with the potential to cause loss of visual acuity, decreased color vision, and decreased depth perception. These visual changes may become permanent and require removal of aviators from flight status. This study reviews 55 eyes of 47 USAF aviators with ICSC examined at the United States Air Force School of Aerospace Medicine (USAFSAM), Brooks AFB, TX. Clinical and aeromedical findings, both on initial and on follow-up ophthalmic examination were studied. Ninety-seven percent of aviators otherwise medically qualified were ultimately returned to flight status. Overall, 51% had recurrent episodes, 17% had bilateral disease, and 13% underwent laser photocoagulation. Visual acuity correlated with active disease, and there was a trend toward poor stereopsis and diminished color vision with worsening visual acuity. Eighty-six percent attained a final visual acuity of 20/20 or better. On final examination, 90% had normal stereopsis, 87% had normal color vision, and 49% had a normal central visual field. Eyes with recurrent disease tended to have degraded final visual acuity, stereopsis, color vision, and central visual field. The visual and aeromedical prognosis from a single attack of ICSC is generally favorable, but repeated attacks can lead to a significant decrease in visual functions that may jeopardize flying status.

Adult↗
PubMedDate not supplied

Acquired dyschromatopsia in glaucoma.

Recent studies have suggested that the recognition of blue-yellow color vision deficits may have some predictive value in determining which ocular hypertensives are at risk of developing glaucoma and in monitoring the progress of the disease in glaucoma patients. This article reviews current theories of normal color vision and the differences that may occur in glaucoma, outlining methods of color vision testing and interpretation, and summarizing the results of recent studies.

Adaptation, Physiological↗
PubMed1979

Cerebral color blindness: an acquired defect in hue discrimination.

In contrast to the traditional view that striate visual cortex (area 17) is surrounded by two homogeneous cortical areas (areas 18 and 19), recent studies have shown that mammalian extrastriate visual cortex contains several anatomically and functionally distinct subregions. One such region, the V-4 complex of the rhesus monkey, is highly specialized for the analysis of color information, suggesting that a lesion in a homologous region might produce a defect in color vision while sparing other visual functions. We have studied a patient whose clinical syndrome supports this suggestion: a 44-year-old man with normal color vision suffered two cerebral infarctions that produced first a right and then a left superior homonymous quadrantanopia and also caused prosopagnosia, topographical disorientation, and severely impaired color vision. Computed tomography demonstrated extensive lesions in both inferior occipital lobes in the territories of the lateral branches of the posterior cerebral arteries, involving the lingual and medial occipitotemporal gyri bilaterally; these gyri contain the inferior portion of striate cortex and segments of extrastriate visual cortex. The patient had no difficulty in giving the correct color names associated with common objects presented either verbally or in outline drawings. Standardized testing with the Farnsworth-Munsell 100-hue test, the Nagel anomaloscope, and a method that tests for just-noticeable differences between monochromatic stimuli all showed that the patient's ability to distinguish one color from another was markedly imparied but not totally absent. In contrast, visual acuity, reading, visually guided eye movements, and stereopsis were normal. Cells in the V-4 complex of monkey extrastriate cortex are highly specialized for distinguishing one color from another; the hue discrimination deficit that was demonstrated in this patient with cerebral color blindness indicates that a region or regions with similar function has been damaged.

Adult↗