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Vision Deficiency (vision + deficiency)

Distribution by Scientific Domains
Medical Sciences100%

Kinds of Vision Deficiency

  • colour vision deficiency
    		•

    Selected Abstracts

    The ChromaGen contact lens system: colour vision test results and subjective responses

    OPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 3 2001
    Helen A. Swarbrick
    Summary The ChromaGen lens system is designed to enhance colour perception in colour vision deficiency (CVD). To investigate its efficacy, 14 CVD subjects were prescribed ChromaGen contact lenses. Colour vision tests (Ishihara, Farnsworth Munsell D-15, Farnsworth Lantern) were administered at baseline, lens dispensing, and after a 2-week lens-wearing trial during which subjective responses were recorded daily using visual analogue scales. ChromaGen lenses significantly reduced Ishihara error rates(p<0.001; ANOVA), particularly for deutan subjects. There was also a significant reduction in errors(p<0.005) on the D-15 test. Conversely, lens wear had no significant effect on Farnsworth Lantern test performance. Subjectively, subjects reported enhanced colour perception, but poor vision in dim light. Judgement of distance and motion were only slightly affected. We conclude that ChromaGen lenses may enhance subjective colour experience and assist in certain colour-related tasks, but are not indicated as an aid for CVD in occupations with colour vision-related restrictions. [source]

    Abnormal colour vision is a handicap to playing cricket but not an insurmountable one

    CLINICAL AND EXPERIMENTAL OPTOMETRY, Issue 6 2007
    Ross W Harris BAppSc LOSc FVCO
    Background:, Two studies have reported that abnormal colour vision is under-represented among cricketers, presumably because cricketers with abnormal colour vision have difficulty seeing the red ball against the green grass of the cricket field and the green foliage around it. We have previously reported on the difficulties of five cricketers with abnormal colour vision but we have also reported that one of Australia's finest cricketers was a protanope. This survey was undertaken to confirm the under-representation of abnormal colour vision among cricketers and to ascertain whether those playing tend to be (1) those with a mild colour vision deficiency, (2) bowlers rather than batsman and (3) prefer to field close to the batsman rather than in the outfield. Methods:, The colour vision of 293 members of seven Melbourne Premier cricket clubs was tested using the Ishihara test. Those who failed were examined further to confirm their abnormal colour vision, to assess its severity with the Farnsworth D15 test and to classify it as either protan or deutan using the Medmont C100 test. A questionnaire about cricketing ability and problems playing cricket was administered. Results:, Twenty-six (8.9 per cent) of the cricketers had abnormal colour vision, of whom six played in the First Grade (6.7 per cent of First Grade players). The proportion of cricketers with a severe deficiency was significantly less than expected for the First Grade players. There were only two protans. Bowlers were not over-represented among the colour vision defective cricketers but those preferring to field close to the batsman were significantly over-represented. Conclusion:, Abnormal colour vision is a modest handicap to playing cricket, especially at the higher levels of the game. It may impede batting and the ability to field in the outfield. [source]

    Assessment of inherited colour vision defects in clinical practice

    CLINICAL AND EXPERIMENTAL OPTOMETRY, Issue 3 2007
    Barry L Cole PhD MAppSc BSc LOSc
    Background:, Colour vision deficiency (CVD) has a high prevalence and is often a handicap in everyday life. Those who have CVD will be better able to adapt and make more informed career choices, if they know about their deficiency. The fact that from 20 to 30 per cent of adults with abnormal colour vision do not know they have CVD suggests that colour vision is not tested as often as it should be. This may be because of practitioner uncertainty about which tests to use, how to interpret them and the advice that should be given to patients on the basis of the results. The purpose of this paper is to recommend tests for primary care assessment of colour vision and provide guidance on the advice that can be given to patients with CVD. Methods:, The literature on colour vision tests and the relationship between the results of the tests and performance at practical colour tasks was reviewed. Results:, The colour vision tests that are most suitable for primary care clinical practice are the Ishihara test, the Richmond HRR 4th edition 2002 test, the Medmont C-100 test and the Farnsworth D15 test. These tests are quick to administer, give clear results and are easy to interpret. Tables are provided summarising how these tests should be interpreted, the advice that can be given to CVD patients on basis of the test results, and the occupations in which CVD is a handicap. Conclusion:, Optometrists should test the colour vision of all new patients with the Ishihara and Richmond HRR (2002) tests. Those shown to have CVD should be assessed with the Medmont C-100 test and the Farnsworth D15 test and given appropriate advice based on the test results. [source]

    One of Australia's greatest cricketers was a protanope: a genetic detective story solved with the help of Schmidt's sign

    CLINICAL AND EXPERIMENTAL OPTOMETRY, Issue 6 2005
    Ross W. Harris BAppSc LOSc FVCO
    Abnormal colour vision is under-represented among first class cricketers (Goddard N and Coull B BMJ 1994; 309: 16841685) and interviews with cricketers, all of whom had a mild colour vision defect, suggest there may be times when they lose sight of the red cricket ball against green surrounds (Hams and Cole Clin Exp Optom 2005; 88: 176,180). It is possible that severe abnormal colour vision precludes playing cricket at its highest competitive level. It is known that Bill Ponsford, who played Test cricket from 1924 to 1934 and was one of Australia's greatest batsmen, had abnormal colour vision. We have diagnosed him to be a protanope by tracing the abnormal colour vision exhibited by some of his descendents. We used Schmidt's sign using the Medmont ClOO colour vision test to identify carriers of the protan gene to trace the protanopic gene to Ponsford with greater certainty. That such an accomplished batsman and highly regarded outfielder should have a severe colour vision deficiency suggests that abnormal colour vision might not be, or at least need not be, a handicap to playing cricket at the most competitive levels. [source]

    Protan colour vision deficiency and road accidents

    CLINICAL AND EXPERIMENTAL OPTOMETRY, Issue 4 2002
    Barry L Cole PhD LOSc FAAO
    Background: Protans are precluded from holding a commercial driver's licence in Australia because they have a substantially reduced ability to see red lights and have more road accidents involving signal lights. This exclusion has been in place since 1994 but is likely to be abandoned following a current review of medical standards for commercial drivers. This paper reviews the level of risk of road accidents due to protan colour vision deficiency. It also addresses the question of whether it is fair to regard all protans as having a higher risk of road accident because some protans might have a sensitivity to red light that is as good as that of some people with normal colour vision. Methods: Data of two studies by Verriest and co-workers are re-analysed to estimate the degree of overlap of the protan and colour normal distributions of sensitivity to red light. Results: Field trial data show that protans have a very reduced visual range for red signals compared to colour normal observers but there is considerable variability among both classes of observers and the distributions do overlap. However, some variability is due to differences in observers' choices of a detection criterion, their speed of response and the measurement method. A laboratory study of the spectral sensitivity of protan and colour normal subjects that largely removes these sources' variability shows that all protans have a sensitivity to red light that is less than that of the least sensitive colour normal. Conclusion: It is reasonable to conclude that all protans, regardless of the severity of their defect, have a lesser ability to see red signals than colour vision normal observers and for that reason will have a higher risk of road accident. [source]