Rod densitometry in congenital stationary night blindness

Rod densities were measured in ten patients with congenital stationary night blindness (CSNB) using the Utrecht densitometer. In five patients rod density was within the range observed in a group of control subjects. One of these patients reached a normal rod two-way density after a prolonged regeneration time. In five patients with different hereditary patterns of CSNB we found decreased amounts of rhodopsin. These observations deviate from the findings on four CSNB patients hitherto described in the literature, where normal concentrations and kinetics of rhodopsin were found. We observed no relationship between the age of CSNB patients and mode of rhodopsin kinetics. No inconsistencies between rod densitometry and electro-retinography were revealed. The different electroretinography patterns were not helpful in predicting the densitometric responses in CSNB. The present results included, five of fourteen CSNB patients ever studied with the technique of retinal densitometry show abnormal rhodopsin kinetics. We propose a schema of CSNB subtyping based on the different rhodopsin kinetics.