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P.A. Quiros, D. Fix Ventura, S.R. Salomao, V. Carelli, M. Gualtieri, A.G. Fernandes Oliveira, L.H. M. C. Pereira, M. Moraes, A. Berezovsky, A.A. Sadun; Selective Loss of Color Discrimination in Carriers of Leber’s Hereditary Optic Neuropathy from a Giant Brazilian Pedigree. . Invest. Ophthalmol. Vis. Sci. 2004;45(13):4336.
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© ARVO (1962-2015); The Authors (2016-present)
Objective: To determine colour thresholds in non–affected 11778 LHON carriers with the Cambridge Colour Test (CCT). Methods: Subjects were LHON carriers (n=46) from a previously described giant Brazilian pedigree. Subjects were divided into three age groups ( 8–30, 31–45, >45) and compared with age matched controls (n= 77). All subjects were tested monocularly. Inclusion criteria included absence of known ophthalmological complaints and 20/30 bc VA or better. We used the Trivector procedure of the Cambridge Colour Test – CCT (CRSLtd), with a VSG 2/5 card and a Sony Trinitron video monitor. The system was calibrated with a Minolta CS1000 photometer. McAdam Ellipses were obtained from carriers with altered Trivector thresholds. Results:35 of 46 carriers (76%) had both abnormal protan and deutan thresholds. Fewer carriers had abnormal tritan thresholds 15 of 46 (32%) than protan or deutan losses in the three groups. The lowest proportion of abnormal tests were in those above 30 years old. The Kruskal–Wallis ANOVA showed significant differences between carriers with abnormal thresholds and controls, for all age groups and color confusion axes (p<0.05). Further comparison between carriers with abnormal and normal results was statistically significant for the oldest age group. (p<0.05). Conclusion:Although 11778 LHON carriers have been regarded as "unaffected" there is a continuum of color vision loss in this population. The proportion of carriers with tritan loss is much smaller than those with protan or deutan losses, in all age groups. This result further supports the idea of LHON as a chronic disease; and is in line with our own finding of sparing of the tritan axis in severely affected LHON patients.
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