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Performance of air traffic control tasks by protanopic color defectives.

Air traffic controllers perform a number of tasks which involve color identification, color discrimination, and color naming. Normal color vision is required for air traffic controllers, although the requirement is currently under review. The most critical task involving color is the distinction of red and black on flight strips; the distinction must be made reliably, quickly, and routinely for flight safety. In this study of four protanopes and three normals, all the protanopes were unable to make this distinction reliably under the lighting levels encountered at air traffic control (ATC) centers, whereas none of the normals had any difficulty. Protanopes also made numerous errors with other ATC tasks involving color. The use of a red filter, often recommended to aid color defectives, actually made performance worse and additionally compounded the usual protanopic loss of brightness for red light. When Snellen visual acuity was tested using the red filters, protanopes needed up to four times larger letters than the color normals. It is concluded that protanopes have inadequate vision for safe performance of some current ATC tasks.

Aviation

Limited improvement of color deficient vision with colored filters.

For over a hundred years, colored filters have helped people with less than normal color vision, to discriminate colors. Filtered light does not restore missing or abnormal pigments within the defective eye. Contrast and discrimination provided by a suitable colored filter can help discrimination of a given set of colors, but may prevent seeing other sets of colors. The use and limitations of color filters are described as aids for color deficient vision.

Color Vision Defects

A study of some genetic markers among Ramgarhias, an artisan caste of Punjab.

156 males and 63 females belonging to the Ramgarhia community, an endogamous group of Punjab, were taken for the study of genetical markers like taste ability to PTC, mid digital hair and colourblindness, whereas 75 (50 males and 25 females) were tested for serum proteins. 71.70% males and 73.85% females were found to be tasters. The mid digital hair was absent in 67.34% of females and 64.74% of males. No female was found to be colourblind, however, 4.48% males were found having defective colourvision. The phenotypic frequencies of Hp 2--2, Hp 2--1 and Hp 1--1 were found to be 64.00%, 32.00% and 4.00%, respectively. No variant of transferrins and albumin was found.

Blood Proteins

[Incidence of color blindess in East African Negroes].

1008 Bantu and 295 Nilotes of Kenya were tested with regard to protanopia-deuteranopia by means of the ISHIHARA-Plate No. 11 (16 plates edition). Four (0.55%) of the male Bantu and two (1.03%) of the male Nilotes showed a partial or total red-green-blindness. With the females of these samples no case of defective colour vision was observed.

Black People

Gene frequency and type of colour blindness in Ethiopians.

All 954 boys and 1064 girls attending two schools in north-western Ethiopia were tested in February 1988 for colour blindness using the Ishihara plates. A total of 40 colour blinds (4.2%) were found among males and 2 (0.2%) among females. There were 31 (3.2%) deutans and 9 (0.9%) protans among males. Both female colour blinds were deutans. This study confirms a previous observation on the gene frequency of colour blindness in this population. For the first time it also provides information on the frequency of this polymorphism in female Ethiopians, as well as types of red-green defects.

Adolescent

Xenon arc and argon laser photocoagulation in the treatment of diabetic disc neovascularization. Part 2. Effect on colour vision.

Patients with long-standing diabetes develop acquired colour vision defects in parallel with retinal vascular changes. This may take the form of an overall loss of hue discrimination or a specific tritan (blue) defect. A battery of colour vision tests can be used to monitor the different features of diabetic retinopathy and to assess the effects of treatment. Diabetic disc new vessels form when approximately a quarter of the retina is ischaemic. The colour vision defect in these patients is usually severe and is frequently tritanopic. The effect of both argon laser and xenon arc panretinal photocoagulation is to increase the severity of the colour defect. All the eyes examined were tritanopic after treatment and did not recover during the 12-month follow-up period. The severity of this acquired colour vision defect can result in practical difficulties for the patient.

Adult