Color Matching and Foveal Densitometry in Patients and Carriers of an X-linked Progressive Cone Dystrophy

We describe a family with an as yet undescribed form of X-linked progressive cone dystrophy in a five-generation pedigree, from which we report here the results of 17 male patients and 31 obligate and 13 possible female carriers. The affected males showed the characteristic picture of cone dystrophy. Foveal cone photopigment density was impaired (judged from anomaloscope settings and foveal densitometry), even at an early stage of the disease. The carriers showed no fundus abnormalities, except occasional changes due to myopia. The anomaloscope demonstrated mild pseudoprotanomaly in 27 of 31 obligate carriers and in six of 13 possible carriers. Foveal densitometry findings performed in 11 carriers always agreed with the anomaloscope findings. We conclude that the findings of pseudoprotanomaly and abnormal density differences in females of this family were the only ocular abnormalities and thus are indicative of the carrier state.