Sex-difference in progressive cone dystrophy. I

The authors report a family with an X-linked intermediate inherited progressive cone dystrophy. Both the affected males and heterozygote females present myopia and diminished acuity so that routine ophthalmological examination erroneously points to an X-linked dominant inherited myopia. Only the evaluation of the cone function by electroretinography and color vision examination reveals a sex-difference, thus visual function studies are a conditio sine qua non to make a correct diagnosis. the disease starts as a peripheral cone disease and progresses to a diffuse cone disease and perhaps at an advanced age to a cone-rod disease. Signs of the carrier state are myopia and a diminished visual acuity and to a minor degree some depression of the cone electroretinogram and an enlargement of the anomaloscope equation zone towards red.