Biomedical subjects

Ross W Harris

Publications and source records attributed to Ross W Harris.

3 recordsLinked to original sources

PubMed2005

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

Abnormal colour vision is under-represented among first class cricketers 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. 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 C100 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 out-fielder 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.

Australia↗

PubMed2005

Five cricketers with abnormal colour vision.

Five cricketers with abnormal colour vision, all of whom had mild deuteranomaly, reported occasions when they had lost sight of the ball when the background was the green grass of the playing field or the green of grassy banks or trees surrounding the playing field. While these five cricketers demonstrate that mild deuteranomaly does not preclude playing cricket successfully at a competitive level, their responses to questions at interview suggest that those with more severe forms of abnormal colour vision may be at a disadvantage. This conclusion is consistent with the under-representation of abnormal colour vision in a sample of first class county cricketers in England reported by Goddard and Coull (BMJ 1994; 309 1684-1685).

Adult↗

PubMed2005

Diagnosing protan heterozygosity using the Medmont C-100 colour vision test.

BACKGROUND: A surprisingly high 15 per cent of women in Caucasian societies are carriers of the genes for abnormal colour vision but there is no clinical method to identify them. It has long been known that heterozygotes for the protan colour vision deficiencies can demonstrate a reduced luminous sensitivity to red light. This is known as Schmidt's sign, which is thought to arise from mosaicism (Lyonisation). The Medmont C-100 colour vision test measures relative spectral sensitivity using flicker photometry to differentiate protans and deutans. It should be able to diagnose Schmidt's sign. METHOD: We tested six known protan heterozygotes (four whose sons have a protan colour vision deficiency and two whose fathers are protan) with the Medmont C-100 test. RESULTS: All six heterozygotes made average settings of -1.75 or more negative at the Medmont C-100 test, settings which are at or beyond the boundary of the distribution of settings made by observers with normal colour vision. There have been two previous cases reported in the literature of protan heterozygotes, who made protan settings on the Medmont C-100 or its predecessor test, the OSCAR. We also tested six daughters of the known heterozygotes, 50 per cent of whom are likely to be heterozygotes. Four of the six (66 per cent) made protan settings on the Medmont C-100. The other two made normal 0.0 settings. CONCLUSION: We conclude that the Medmont C-100 can be used clinically to diagnose carriers of protan colour vision deficiency.

Color Perception Tests↗