[Clinical findings in autosomal recessive syndrome of blue cone hypersensitivity].

BACKGROUND

Intrafamilial variability of the syndrome of night blindness, maculopathy, and enhanced S-cone hypersensitivity was examined.

PATIENTS AND

METHODS

Siblings with a history of night blindness and reduced visual acuity were examined clinically, psychophysically, electroretinographically (ERG), and electro-oculographically (EOG).

RESULTS

The siblings had had night blindness since early childhood and reduced visual acuity since the age of 20 years. Ophthalmoscopy showed degenerative, pigmented changes and subretinal spots, while one sibling had cystic lesions in the fovea. Scotopic ERG showed no rod-driven responses, while large, slow waveforms were detected in response to bright flashes. Photopic ERG induced responses similar in time, amplitude, and configuration to those of the dark-adapted ERG. The b-wave configuration was unchanged in response to chromatic stimuli. However, photopic ERG was more sensitive to blue and white than to red stimuli. The light peak on EOG was reduced.

CONCLUSIONS

The enhanced S-cone sensitivity syndrome was expressed to a different degree of severity and probably inherited in an autosomal recessive mode. These unusual ERG findings may be due to a depressed rod system and an increased number of S-cone photoreceptors, postreceptoral circuits, and S-cone sensitive ganglion cells.