[Color vision defect. A early sign of Sorsby retinal dystrophy?].

In 34 asymptomatic patients from three families at 50% risk of developing Sorsby's fundus dystrophy, colour contrast sensitivity was measured. In 16 the thresholds--mainly of the tritan axis--were raised above the normal values. It is concluded that testing of colour vision is useful in detecting the abnormal genotype. Raised colour contrast sensitivity was not observed before the first fundus or fluorescein angiographic changes in two of the families, while the colour defect occurred in the absence of ophthalmoscopic abnormality in the third family. Therefore, our results support the clinical suggestion that Sorsby's fundus dystrophy is more than one disease.