Toxic risks and nutritional benefits of traditional diet on near visual contrast sensitivity and color vision in the Brazilian Amazon.

BACKGROUND: Visual functions are known to be sensitive to toxins such as mercury (Hg) and lead (Pb), while omega-3 fatty acids (FA) and selenium (Se) may be protective. In the Tapajós region of the Brazilian Amazon, all of these elements are present in the local diet. OBJECTIVE: Examine how near visual contrast sensitivity and acquired color vision loss vary with biomarkers of toxic exposures (Hg and Pb) and the nutrients Se and omega-3 FA in riverside communities of the Tapajós. METHODS: Complete visuo-ocular examinations were performed. Near visual contrast sensitivity and color vision were assessed in 228 participants (≥15 years) without diagnosed age-related cataracts or ocular pathologies and with near visual acuity refracted to at least 20/40. Biomarkers of Hg (hair), Pb (blood), Se (plasma), and the omega-3 FAs eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in plasma phospholipids were measured. Multiple linear regressions were used to examine the relations between visual outcomes and biomarkers, taking into account age, sex, drinking and smoking. RESULTS: Reduced contrast sensitivity at all spatial frequencies was associated with hair Hg, while %EPA, and to a lesser extent %EPA+DHA, were associated with better visual function. The intermediate spatial frequency of contrast sensitivity (12 cycles/degree) was negatively related to blood Pb and positively associated with plasma Se. Acquired color vision loss increased with hair Hg and decreased with plasma Se and %EPA. CONCLUSIONS: These findings suggest that the local diet of riverside communities of the Amazon contain toxic substances that can have deleterious effects on vision as well as nutrients that are beneficial for visual function. Since remediation at the source is a long process, a better knowledge of the nutrient content and health effects of traditional foods would be useful to minimize harmful effects of Hg and Pb exposure.

Night blindness, yellow vision, and yellow skin: symptoms and signs of malabsorption.

BACKGROUND: Rapidly progressing bilateral night blindness in an elderly patient suggests primarily a diagnosis of paraneoplastic retinopathy. Occasionally diffuse rod dysfunction can result from vitamin A deficiency. HISTORY AND SIGNS: A 70-year-old man complained of progressive night blindness and xanthopsia for the past 6 months. Visual acuity was 0.8 in both eyes with severe dyschromatopsia. Slit-lamp and fundus examination were normal. Visual field disclosed bilateral depression. Scotopic full-field ERG was severely reduced. The patient's medical history revealed an acute pancreatitis one year ago, followed by chronic jaundice and an increased blood bilirubin. Serum vitamin A level was decreased to 0.1 micromol/L (normal range 1.5 to 4.0). THERAPY AND OUTCOME: Intramuscular injections of vitamin A were provided. Subjective visual improvement was reported already one day after initiation of therapy. Scotopic full-field ERG was markedly improved 3 days after the injection and was only slightly subnormal 3 months later. CONCLUSIONS: In developed countries, vitamin A deficiency usually results from malabsorption syndromes and manifests initially by rod more than cone dysfunction. This diagnosis should be entertained early as vitamin A supplementation induces a rapid restoration of vision.

Intervention study on acquired color vision deficiencies in styrene-exposed workers.

The main aim of the study was to examine the possible effects of occupational exposure to styrene on color vision function and the course after reduction of exposure. Color vision function was examined in 22 styrene-exposed laminators and 11 control subjects at a boat manufacturing plant. The Lanthony D-15 desaturated panel was used to test acquired dyschromatopsia. In all, six examinations were performed: Monday morning and Thursday afternoon of the same week, before and immediately after a vacation of 4 weeks (altogether, phase 1), and approximately 10 months later (phase 2), after the exposure level of styrene had been reduced. Styrene uptake was objectified by biological monitoring measuring the metabolites mandelic acid and phenylglyoxcylic acid in urine samples taken on Thursday afternoon. In both Thursday examinations, styrene-exposed workers had higher color confusion index (CCI) values compared with controls, which indicated quantitative color vision loss. After an exposure-free period of 4 weeks, a significant decrease of CCI values to normal range was found in laminators. Reexamination 10 months later showed also lower CCI values in exposed workers, indicating a dose-effect relationship. Abnormal CCI values occurred primarily in subjects with an excretion of approximately 500 to 600 mg mandelic acid plus phenylglyoxcylic acid per gram creatinine or more. We concluded that styrene-induced color vision dysfunction is reversible after an exposure-free interval of 4 weeks. The current Biological Tolerance Value of 600 mg mandelic acid plus phenylglyoxcylic acid per gram creatinine, as used in Germany, protects styrene-exposed workers from this subclinical effect.

Retinal function in Swedish ophthalmologists using argon lasers as reflected in colour contrast sensitivity. Normal thresholds in the great majority of the cases.

PURPOSE: To map the colour contrast sensitivity (CCS) and possible elevations of colour contrast thresholds in Swedish ophthalmologists operating argon lasers. MATERIAL AND METHODS: CCS was measured by a computer and colour monitor system developed by Arden and co-workers. CCS of 58 Swedish ophthalmologists, all users of argon laser, was compared to 26 age-matched controls. The ophthalmologists provided information on their professional use of lasers, whether the laser was equipped with a blue-absorbing filter, and the length of time spent in retinal surgery. RESULTS: There was no significant difference in colour vision comparing laser-users to controls (p>0.2). However, eight subjects showed elevated tritan thresholds (>1 SD above mean), in three of the cases an elevation >2 SD above mean. All these colleagues had an extensive exposure to blue-green laser and/ or a long time spent operating. Compared to others, they had performed more laser sessions prior to the lasers being equipped with protecting filters (p<0.01). CONCLUSION: Normal thresholds were found in a majority of the cases and no permanent impairment of retinal function was observed among these ophthalmologists. However, the laser-users with the greatest number of sessions seemed to show a certain decrease in retinal function as reflected in tritan thresholds.

[Computer-based determination of red/green color vision defects]. / Computer-basierte Bestimmung von Rot/Grün-Farbanomalien.

A commonly used method of investigating colour vision, that is, the ability of the human visual system to discriminate colours, is based on the use of isochromatic colour plates, such as those used in the Ishihara test. The present paper describes a new computer-based method of determining red/green colour vision deficiencies. The method involves the presentation of Ishihara colour plates on a computer monitor. It has been verified experimentally that, despite the differences between the spectral emission of the computer screen and the daylight reflected by the Ishihara plates, the method is capable of distinguishing between subjects with from those without colour vision deficiencies. For screening purposes, the use of a reduced number of plates is suggested. This suggestion makes use of nine instead of 14 plates, and the criterion of two incorrectly recognized plates to determine a colour vision deficiency.

Efficiency of the Ishihara test for identifying red-green colour deficiency.

The Ishihara test is the most widely used screening test for red-green colour deficiency. Results obtained by 401 people with red-green colour deficiency show that the combined sensitivity of the Transformation and Vanishing plates of the 38 plate Edition of the Ishihara plates is 95.5% on eight errors, 97.5% on six errors and 99.0% on three errors. The Hidden digit designs only identified approximately 50% of colour-deficient subjects. The protan/deutan classification plates were found to be more effective for deutans than for protans. No classification was obtained for 18% of protanopes and 3% of deuteranopes who saw neither figure on classification plates; 40% of protanomalous trichromats and 37.5% of deuteranomalous trichromats saw both classification figures and were classified on the relative luminance (clarity) of these figures. The specificity of the Ishihara test was determined in a previous study (Birch and McKeever, 1993) and the results combined with the present data to obtain the overall efficiency of the Ishihara plates for a representative cross section of colour-deficient subjects.

Performance of color-dependent air traffic control tasks as a function of color vision deficiency.

BACKGROUND: This experiment was conducted to validate the requirement for normal color vision in Air Traffic Control Specialist (ATCS) personnel who work at en route center, terminal, and Flight Service Station (FSS) facilities. METHODS: A data base was developed involving 121 individuals with normal color vision, 31 simple and 44 extreme anomalous trichromats, and 48 dichromats; both protans and deutans were included. The performance of subjects with normal color vision was compared with the performance of individuals with various classifications of color vision deficiencies on a battery of color-dependent ATCS tasks. Simulations of the ATC color tasks concerned color coding in flight progress strips (at en route centers), aircraft lights and Aviation Signal Light indicator (in tower operations), and color weather radar (at FSS's). RESULTS: Errors were rare among normal trichromats. Mean errors were significantly higher at every level (degree) of color vision deficiency. Approximately 6% of color deficient subjects were able to perform ATC color tasks without error. The 6% were all from the simple anomalous trichromat category; all extreme anomalous trichromats and dichromats were prone to error on ATC tasks. CONCLUSIONS: We conclude that these findings provide support for the requirement of normal color vision in the initial medical screening of ATCS personnel.

[Color vision test for detection and evaluation of dyschromatopsia]. / Test chromatique pour dépistage et étalonnage des dyschromatopsies.

METHODS: The color vision test for diagnosis and evaluation of the dyschromatopsias consists of a set of 92 colored test charts of the pseudochromatic type, a lamp and a test report giving a graphic image of the sensitivity to color deficiency. RESULTS: The test makes it possible to identify each neutral zone of all types of dyschromatopsia, places the neutral zone within the color spectrum and establishes its extent according to 6 axes (Protan, Deutan, Tritan, Tetartan, Scotopic and Monochromatic) and 10 levels. The visual sensitivity to color is measured on a 10 point scale, just as visual acuity is. Between a normal sensitivity to color, which is marked 1, and an anopia (i.e complete lack of visual sensitivity to color along one axis), marked 0, there are 9 intermediary levels marked 0.9; 0.8: 0.7; 0.6: 0.5; 0.4; 0.3; 0.2 and 0.1. CONCLUSION: Testing is important for all kinds of eye diseases or common diseases which affect eyesight making possible not only early diagnosis of a disease but also treatment follow-up.

Color vision testing of healthcare personnel.

The purpose of the study was to identify and describe color vision testing of healthcare personnel who do glucose monitoring within a hospital. The subjects were 359 members of a nursing staff. Data were collected from nurses participating in a certification program for blood glucose monitoring. The lshihara plates were used to screen for a color vision deficiency. The results offered no evidence that screening of staff provided any benefit for patient care.

Colour vision screening in children: an evaluation of three pseudoisochromatic tests.

We examined 513 children (258 boys and 255 girls), between 3 and 11 years of age, with three pseudoisochromatic tests which involve different visual tasks. These were a selection of numeral designs from the Ishihara test, the Ishihara test for Unlettered Persons and the Velhagen Pfügertrident test. Eighteen children were found to be colour deficient. The symbol designs of the Unlettered Persons test were found to be the quickest and most effective method for examining children under 7 years of age. After 7 years of age the symbol designs of the Unlettered test and the numeral designs of Ishihara test were equally effective. The preferred numeral designs for screening children with the Ishihara plates are listed. Verbal identification always produced the most accurate results. Drawing over the figures or selecting replicas increased the viewing time and assisted children with normal colour vision to see both figures in transformation designs, especially pathway designs. The Velhagen Pfügertrident test was found to be unreliable for colour vision screening and younger children had difficulty performing the figure matching task.

Color-vision deficiency--what does it mean?

Color-vision deficiency is a disorder affecting a significant proportion of the population, yet it remains poorly understood by school personnel as well as the general public. This article examines the many ways abnormal color perception affects peoples' lives. The role of the school nurse in detection of the problem, plus education and counseling of the affected student, parents, and teachers is discussed.

Failure of many ophthalmologists to use lasers safely.

In 1990, after the detection of impairment of colour discrimination in laser operators, the College of Ophthalmologists recommended safety guidelines for the use of lasers. We measured the effectiveness of these guidelines and their impact on ophthalmological practice in the United Kingdom. Previously, in ophthalmologists not following the guidelines, there was a deterioration in colour discrimination after a laser session. No such deterioration was found in 10 ophthalmologists tested who adhered to the guidelines, but their colour discrimination was significantly worse than that of controls. Replies to a questionnaire disclosed that one third of senior ophthalmologists were unaware of the practices recommended.

The True Daylight Illuminator (TDI): a less expensive source of illumination for color vision screening.

This experiment was designed to examine the feasibility of using the True Daylight Illuminator (TDI) as an illumination option for conducting color vision screening with the Ishihara Test(s). The MacBeth Easel Lamp was designed to provide proper illumination for performing color vision screening with a variety of pseudoisochromatic (PIC) plate tests including the Ishihara. However, over the years, the MacBeth Lamp has become so expensive that many smaller programs cannot afford to purchase one. This problem has promoted the use of alternate light sources that have had a deleterious effect on test results and in some instances contributed to job discrimination. Recently the MacBeth Division of the Kollmorgan Corporation discontinued the manufacture of the MacBeth Lamp due to lack of demand. Thus, it is important to find an inexpensive illumination option for conducting color vision screening. Two groups of subjects were used to compare test results for the 24-plate edition of the Ishihara Test using both the MacBeth Lamp and the True Daylight Illuminator. The first group contained 45 subjects with inherited color defective vision. The second group was made up of 30 color normals. The Nagel anomaloscope was used to confirm the color vision status of the subjects in both groups. Statistics to test the significance of differences between group means clearly demonstrated that there were no significant differences between the mean error scores of the two groups for these two pieces of equipment. Thus, it was concluded that the TDI can be used in lieu of the MacBeth Easel Lamp for screening color vision with the Ishihara test.

Pre-employment colour vision testing.

Male candidates (1020) for employment in occupations that required discrimination of colour were subjected to the Ishihara test and two trade tests of colour perception, the Giles Archer Lantern test and the Electricity Supply Industry (ESI) wire test. One hundred candidates failed the Ishihara test, 61 of the 100 passed both trade tests; 16 of the 100 passed the wire test alone and 7 of the 100 passed the lantern test alone but only 16 failed all 3 tests. Seventy-seven of the 84 who passed some part of their colour perception assessment were offered employment appropriate to their colour vision ability. Eleven of the 16 who passed the wire test alone and 3 of the 6 who passed the lantern test alone successfully entered employment. The Ishihara test, whilst being a useful screening test, is not sufficient on its own as a test of suitability for employment; one or more trade tests should be administered before rejecting candidates who fail it.

Colour vision testing in pre-school-aged children.

84 children aged from 2 to 6 years were tested with three different pseudo-isochromatic plates: Velhagen Pflügertrident test, Lanthony Tritan Album and Ishihara test. The Velhagen test was correctly interpreted by all of the 6- and 5-year olds, by 80% of the 4-year olds and by 20% of the 3-year olds. The Lanthony Tritan Album was well performed by all of the 6-, 5- and 4-year olds, and by 80% of the 3-year olds. The Ishihara test was acceptably performed by all of the 6- and 5-year olds, by 90% of the 4-year olds and by 40% of the 3-year olds. None of the 2-year olds could understand any of these tests. In the Ishihara test, the winding lines in the plates No. 30 and 32 were difficult for children; the incomplete interpreting of them must be accepted for a correct answer.

[Mass screening of blue color vision in divers with the desaturated Lanthony-15-Hue Test]. / Reihenuntersuchung des Blausinnes bei Tauchern mit dem desaturierten Lanthony-15-HUE-Test.

We tested 1002 persons, 572 divers (including 38 who had diving accidents) and 430 nondivers, for defects of the blue-sensitive system during the years 1988 and 1989. Recent research has shown functional disorders of color vision in divers, linked to previously described alterations of the retinal capillary system and pigment epithelium. The desaturated Lanthony-15-HUE test was used as a screening method. No defect of the blue-sensitive system was found, either in divers or in nondivers. Our results are similar to those of other researchers. One exception was that we found no correlation between age and error score. We found no evidence for retinal damage caused by diving.

[Early diagnosis of congenital disorders of color vision with the Velhagen "Pflügerhaken Color Charts for evaluating color perception" in 3,375 preschool children]. / Frühdiagnostik kongenitaler Farbensehstörungen mit den "Pflügerhaken-Tafeln zur Prüfung des Farbensinnes" von Velhagen bei 3375 Vorschulkindern.

In three series of examinations, 3375 male preschool-age children and 93 adult normal trichromates were tested using the Velhagen Pflügerhaken charts. The authors recommend modifying the evaluation of the results slightly by introducing a "doubteful" category for children who make one mistake or who show hesitation and lack of assurance in interpreting the charts. Using this modified form of assessment, diagnoses of "probably achromatopic" and "doubtful" were made in 7.16% and 2.13% respectively of 1689 preschool-age boys. The failure rate during the test and the duration of the examination were age-dependent, and declined with increasing age from 4.15% to 0.45% and from 1.18 min to 0.59 min, respectively. Most mistakes were made with charts nos. 9, 3, and 5. The results of tests with Pflügerhaken charts are fully comparable with those of other internationally used tests for adults. They can be recommended for screening preschool-age children.

[Screening of early color vision loss in diabetic patients]. / Dépistage des altérations précoces de la vision des couleurs chez les patients diabétiques.

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.

A new test for screening color vision: concurrent validity and utility.

Recognizing the need for an effective test for screening color vision in young children, we have developed a new pseudoisochromatic (PIC) plate test which is useful for a wide variety of observers at different ages. The test consists of four plates and responses can be used to categorize color vision as normal or as either red-green or blue-yellow defective. Results of this validation study with adults, both color normal and red-green defective, show a high degree of correlation between the new test and the Nagel anomaloscope: there were no false positives and only a few false negatives, which occurred with mild deuteranomalous observers. The validity of the test compares favorably to the Ishihara, F-2, and the AO-HRR screening plates. Results with toddlers (3 to 6 years) indicate that the task demands of the test are well suited for testing young children. The percentage of color defectives identified in the toddler sample using the new test is closer to the adult prevalence than results obtained with the F-2 and AO-HRR screening plates, which gave dramatically higher failure rates. The new test is culture-free and can be administered rapidly to both verbal and nonverbal observers using pointing or preferential looking.