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PubMedDate not supplied

[An epidemiological study of congenital dyschromatopsias in schoolchildren].

BACKGROUND: Taking into consideration that present-day communication is based on colours and shapes, the prevalence of anomalies in the chromatic sight in the red-green axis has been studied in the school boys of the city of Albacete. METHODS: The test of Ishihara has been used in an aleatory representative sample; and dyschromatopsic pupils, so classified in this test, have been further explored with the anomaloscopy Pickford-Nicolson, in order to know their anomaly kind and degree. RESULTS: The prevalence obtained is similar to those reported by other studies carried out in the European white race. CONCLUSIONS: Taking into account the transcendence of this phenomenon, we consider that this exploration must be included in the systematic examinations at school labour and general level.

Adolescent↗

PubMed1985

The genetics of tritan disturbances.

Tritan (blue-green) colour vision disturbances have been found in 79 individuals in six families, revealing an autosomal dominant mode of inheritance with a wide variability of test results within families. Evidence is presented that it is--in contradistinction to the X-chromosomally inherited red-green defects--incorrect to make a subdivision between dichromasia (tritanopia) and anomalous trichromasia (tritanomaly). On the basis of three small screening series, totalling 1900 individuals, the frequency of tritan disturbances is estimated to be around 2 per 1000. Seven males have been observed carrying both inherited tritan and red-green defects.

Adolescent↗

PubMed2001

Predicting Farnsworth Lantern success with a six-plate series of the Ishihara pseudoisochromatic plates.

The Farnsworth Lantern (FALANT) is the definitive color vision test for the Navy, Marine Corps, and Coast Guard. It is also the definitive color vision test for aviation personnel in the Army. Results from it are also accepted by the Federal Aviation Administration. For various reasons, it is desirable to have an alternative test that can predict success (i.e., a passing score) on the FALANT. In 1991, it was shown that a 14-plate series of Ishihara pseudoisochromatic plates could predict FALANT success provided the proper passing criteria was chosen. Interest has arisen regarding whether or not a 6-plate series of Ishihara plates can predict FALANT success. A study was undertaken to answer this question. It appears that a 6-plate series of Ishihara pseudoisochromatic plates can predict FALANT success.

Adolescent↗

PubMed1983

Validation of the Holmes - Wright lanterns for testing colour vision.

The recently introduced Holmes - Wright Type A and Type B lanterns and the Farnsworth lantern were administered to 100 observers with normal colour vision and 100 observers with defective colour vision. With the fail criteria adopted, all normals passed the Holmes - Wright Type A lantern and with one exception all normals passed the Farnsworth lantern. However, 8% of normals failed the more difficult Holmes - Wright Type B lantern. It is noted that the normals who fail this lantern test appear to do so not because of poor colour discrimination but because the coloured stimuli presented by the lantern have a point brilliance close to the average chromatic threshold. About one-third of the colour vision defective group passed the Farnsworth lantern and between 14 and 17% passed the Holmes - Wright Type A lantern depending on the test procedure used. Only two mild deuteranomals in the sample of 100 colour abnormal observers succeeded in passing the Holmes - Wright Type B lantern. Dichromats and severe anomalous trichromats fail all three lanterns so that those who pass are all mild anomalous trichromats. A significant proportion of protanomals pass the Farnsworth lantern and some protanomals pass the Holmes - Wright Type A lantern despite their reduced sensitivity to red light and correspondingly reduced signal range for red signals.

Color Perception Tests↗

PubMed1991

Acquired dyschromatopsia among styrene-exposed workers.

We investigated the occurrence of color vision loss in 75 styrene-exposed workers and in 60 referents. Color vision was evaluated by adopting the Lanthony D 15 desaturated panel, a test specifically suited to detect mild acquired dyschromatopsia. The results of the test were expressed as Color Confusion Index. Styrene exposure was evaluated with both environmental and biological monitoring. Airborne levels of the solvent were 3.2 to 549.5 mg/m3. In styrene-exposed workers color vision was significantly impaired when compared with referents matched for age. A significative correlation was found between environmental and urinary levels of styrene and Color Confusion Index excluding the influence of age in multiple regression analysis, indicating the possibility of a dose-effect relationship. The findings suggest that styrene can induce an early appearance of a dose-dependent color vision loss.

Adult↗

PubMedDate not supplied

A novel mutation in the short-wavelength-sensitive cone pigment gene associated with a tritan color vision defect.

Inherited tritan color vision deficiency is caused by defects in the function of the short-wavelength-sensitive (S) cones. This heterozygous group of disorders has an autosomal dominant pattern of inheritance. Amino acid variations of the S cone opsin are rare and all that have been identified thus far are associated with inherited tritan color vision defects. Here we report the identification of a 30-year-old male who made errors on standard color vision tests consistent with the presence of a mild tritan color vision deficiency. We tested the hypothesis that his color vision impairment was due to a mutation in the S cone photopigment gene. He was found to be heterozygous for a mutation that caused the amino acid proline to be substituted in place of a highly conserved leucine at amino acid position 56 in the S cone opsin. This mutation was absent in 564 S cone photopigment genes from 282 subjects who did not make tritan errors. Thus, we conclude that this mutation disrupts the normal function of S cones.

Adult↗

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↗

PubMed2006

The effect of colour defective vision on shade matching accuracy.

One hundred and forty one male dental students and staff were screened for colour-defective vision. Ten colour-defective and 20 non colour-defective subjects then carried out a shade matching exercise using nine selected shades and another matched, shade tab (to test for consistency) from Vita shade guides. All shade matching took place under standard lighting conditions. Each subject also completed a short questionnaire relevant to shade matching. There were no significant differences found between colour-defective and non colour-defective subjects in shade matching abilities. Although both subject groups were similar in their shade matching abilities, individuals with colour defective vision perceived it to be a slightly more difficult exercise.

Case-Control Studies↗

PubMed1993

Colour vision in diabetic patients after photocoagulation treatment. A five-year follow-up.

Colour vision of 60 diabetic patients (60 eyes) was studied after photocoagulation treatment in 1986-87. For the follow-up study 5 years later in 1991-92, 32 of the patients were available. The ages of the patients in the follow-up study varied from 28 to 64 years, the duration of diabetes from 19 to 35 years, the amount of laser spots from 200 to 3174, and the visual acuity from 0.4 to 1.0. As colour vision tests, the Standard Pseudo-isochromatic Plates part 2, Lanthony Tritan Album, Farnsworth Panel D 15, and box III of the Farnsworth-Munsell 100 hue test were used. Of the 32 eyes, 22 (68.8%) had the same results in the colour vision tests, 4 (12.5%) had better results, and 6 (18.8%) had worse results than 5 years earlier. Between Group 1 (colour vision the same or better than 5 years earlier, 26 eyes) and Group 2 (colour vision worse than earlier, 6 eyes) there was a significant difference in the age and in the level of the visual acuity of the patients. The changes in the lens, fundus or visual acuity during 5 years did not seem to have an effect in colour vision.

Adult↗

PubMed2003

Extent of foveal tritanopia in diabetes mellitus.

AIM: To use a colour matching technique to test the hypothesis that the foveal tritanopic zone is increased in size in diabetes mellitus. METHOD: A Wright tristimulus colorimeter was adapted for small field colour matching and colour matches were performed on bipartite fields in the range 12' to 60' of arc. The reference stimulus was 490 nm desaturated with 650 nm and the matching stimulus consisted of either two wavelengths (530 nm and 650 nm) or three (460 nm, 530 nm, and 650 nm). The size of the zone of foveal tritanopia was measured using two alternative forced choice presentations of dichromatic and trichromatic matches made by the observer for different field sizes. 21 diabetic and 12 controls performed the experiment. RESULTS: The results for the controls show a normal distribution, with a median foveal tritanopic zone of 18' of arc. The median for the diabetic patients was also 18' of arc, but the distribution showed a significant skew to the right. A non-parametric test shows a significant difference in comparison with the controls (p = 0.01), with several subjects having extensive zones of foveal tritanopia, reaching up to 1 degree. CONCLUSIONS: In the majority of diabetic subjects the extent of foveal tritanopia is normal; however, there is good evidence that in a small number of subjects the size of the zone is significantly increased. This indicates S-cone pathway damage that is sufficiently severe to lead to dichromatic colour vision in the fovea.

Adult↗

PubMed1993

Color vision deficiencies in the course of acute alcohol withdrawal.

Thirty-six male patients with a diagnosis of chronic alcoholism were detoxified and color vision tests were performed on day 4, 11, and 32 of their abstinence on an inpatient basis (Ishihara color plates, Nagel anomaloscope, three color-matching tests according to Farnsworth). Of the 36 patients, 47.2% manifested color vision deficiencies. The frequency of congenital red/green defects (11.1%) and a ratio of 3:1 deutan/protan defects showed no significant difference from the incidence in the normal population. In 36.1%, manifest acquired color vision deficiencies were diagnosed. Within the course of withdrawal, a marked improvement of these disturbances could be proved. The degree of the disturbance seems to correlate with the severity of withdrawal symptoms, but seems to be unrelated to acute toxic effects of alcohol, nicotine, or medication.

Adult↗

PubMed2003

The Tehran Eye Study: research design and eye examination protocol.

BACKGROUND: Visual impairment has a profound impact on society. The majority of visually impaired people live in developing countries, and since most disorders leading to visual impairment are preventable or curable, their control is a priority in these countries. Considering the complicated epidemiology of visual impairment and the wide variety of factors involved, region specific intervention strategies are required for every community. Therefore, providing appropriate data is one of the first steps in these communities, as it is in Iran. The objectives of this study are to describe the prevalence and causes of visual impairment in the population of Tehran city; the prevalence of refractive errors, lens opacity, ocular hypertension, and color blindness in this population, and also the familial aggregation of refractive errors, lens opacity, ocular hypertension, and color blindness within the study sample. METHODS DESIGN: Through a population-based, cross-sectional study, a total of 5300 Tehran citizens will be selected from 160 clusters using a stratified cluster random sampling strategy. The eligible people will be enumerated through a door-to-door household survey in the selected clusters and will be invited. All participants will be transferred to a clinic for measurements of uncorrected, best corrected and presenting visual acuity; manifest, subjective and cycloplegic refraction; color vision test; Goldmann applanation tonometry; examination of the external eye, anterior segment, media, and fundus; and an interview about demographic characteristics and history of eye diseases, eye trauma, diabetes mellitus, high blood pressure, and ophthalmologic cares. The study design and eye examination protocol are described. CONCLUSION: We expect that findings from the TES will show the status of visual problems and their causes in the community. This study can highlight the people who should be targeted by visual impairment prevention programs.

Blindness↗

PubMed2005

Quantitative phenotyping of chromatic dysfunction in best macular dystrophy.

OBJECTIVES: To quantify chromatic dysfunction in Best disease to reassess the classic categorization of macular chromatic damage and to investigate psychophysical and clinical correlations. METHODS: Color-contrast discrimination was measured using 2 different psychophysical strategies in age-matched control (n = 41) and patient (n = 34) eyes. The first strategy measured performance along 3 main confusion lines (testing cone function), and the second evaluated discrimination ellipses (modified Cambridge Color Test). The main outcome measures were chromatic discrimination variables (confusion line length, ellipse length, angle, and axis ratio) and visual acuity (VA). RESULTS: Significant loss of performance was seen in all color axes in our patients, and it increased monotonically with staging, becoming significant in Fishman stages 2 and 3. The classically assumed preferential type I red-green deficit was true only for stage 4. Substantial chromatic dysfunction occurred even with relatively preserved VA despite that negative correlations between all test variables and VA reached statistical significance. Partial correlation analysis showed that protan/deutan loss was related to VA independent of tritan loss. Statistically significant positive correlations were also found between lesion size and chromatic dysfunction. CONCLUSIONS: Chromatic discrimination is often impaired in Best disease, even when VA is still spared. Our quantitative psychophysical approach shows that the classic categorization as a type I red-green deficit is valid only for disease stage 4.

Adult↗

PubMed1978

Congenital achromatopsia in a Finnish family.

A family with two achromatic members, a sister and brother, is described. Their parents were first cousins. Eye examination of the 34 relatives examined revealed no abnormalities in 32. The son of their youngest brother was deuteranomalous. However, since this recessive trait is X chromosome linked, this failure was not related to the achromatopsia gene. The granddaughter of their eldest brother had difficulties in colour vision tests and was interpreted as an anomalous trichromat of unclassified nature. This might be a slight intermediate heterozygotic manifestation of the gene. The information of those relatives not examined revealed only a deceased paternal aunt who had had poor vision of an unknown cause. Congenital achromatopsia is rare but nevertheless should be kept in mind in cases of unexplained amblyopia. The nature of this disorder justifies the opthalamologist to inform these patients of the hereditary character of this disease and to give advice on educational guidance to them.

Adult↗

PubMed1983

Chromograms of color normals and multiple sclerosis patients.

The Gunkel chromograph was tested on 81 volunteers with normal color vision as indicated by screening with Ishihara plates and the panel D-15. Most of these color normals located their neutral area superior to the geometric center of the chromogram. A minority located their neutral area at the geometric center. Recognition of this variation may prevent misdiagnosis of chromographs of patients suspected of having color vision defects. All 29 eyes with history and VEP findings consistent with optic nerve demyelinization had enlargement of the neutral area, even though visual acuity could be corrected to 20/20.

Adolescent↗

PubMed1991

A survey of color discrimination in German ophthalmologists. Changes associated with the use of lasers and operating microscopes.

Color vision tests were performed on 211 German ophthalmologists during their annual meeting at Essen. The subjects also answered detailed questionnaires about their use of lasers and operating microscopes, and their ocular and general health. It was found that 33% of doctors who use lasers or operating microscopes have decreased color discrimination for colors in a tritan color-confusion axis (greater than 2 standard deviations above normal). There is a relationship between number of patients treated and the degree of threshold elevation. Thirty hours of using the operating microscope produces an increase in tritan threshold equivalent to one panretinal photocoagulation.

Adult↗

PubMed1985

Color-axis determination on the Farnsworth-Munsell 100-hue test.

Error scores on the Farnsworth-Munsell 100-hue test were partitioned into those representing red-green and those representing blue-yellow losses. Data from two groups of normal observers were used. One group showed results characteristic of published norms; one group showed superior performance. Both observers showed a correlation between red-green and blue-yellow scores indicative of a strong performance factor in this test. The difference between blue-yellow and red-green scores eliminates their correlated variance and allows evaluation of the axis. Both groups showed an increase in difference scores, with age indicating development of a blue-yellow axis. This increase was significant for the observers characteristic of the norms. We suggest cutoff scores to allow a decision as to whether a given patient shows a blue-yellow or red-green axis.

Adolescent↗

PubMed1982

Lanthony's new color test. IV. Neutral zone and neutral grays.

The classification of neutral grays is helpful for the differential diagnosis of color vision defects, especially when anomaloscopic examination is not possible. In congenital color vision defects the PR, RP region of the spectrum appears 'dark' to protan-defective subjects and 'light' to deutan-defective subjects. Acquired color vision defects have a common base type, the type III blue-yellow defect. The defect develops depending on the site of the primary lesion and also on the fixation mode. Classification of neutral grays may help in differentiating optic nerve diseases from retinal diseases; when visual functions become mediated by rods, sensitivity shifts and the BV, B region of the spectrum will appear relatively 'light' to the patient.

Color Perception Tests↗