Acquired unilateral night blindness associated with a negative electroretinogram waveform.

PURPOSE

The authors performed clinical, electrophysiologic, psychophysical, and immunologic studies in a patient who presented with an acquired night blindness in one eye to better define the clinical and functional changes in this rare disorder.

METHODS

In addition to an ophthalmologic examination, the patient underwent the measurement of electroretinogram responses, dark-adapted thresholds using a Tübingen perimeter (Oculus, Tubingen, Germany), color vision assessment, kinetic visual-field testing using a Goldman perimeter, and immunologic testing to determine if the serum contained autoantibodies to retinal bipolar cells.

RESULTS

Fundus examination showed no clinically apparent abnormality in either eye. The patient showed a selective reduction in the b-wave amplitude of the rod electroretinogram and an abnormality of the cone electroretinogram ON response in the affected left eye, whereas the rod and cone electroretinograms of the right eye were normal. Rod thresholds in the affected eye were elevated markedly, whereas rod thresholds in the right eye were normal centrally and slightly elevated in the far periphery. Immunologic testing did not show circulating autoantibodies to retinal cells.

CONCLUSIONS

The patient examined in this study showed phenotypic similarities to patients with congenital stationary night blindness and to patients with an acquired form of night blindness associated with cutaneous melanoma (MAR syndrome). The electroretinogram findings from the patient are consistent with an acquired defect in signal transmission from photoreceptors to ON-type bipolar cells. However, the etiology of this unique form of unilateral night blindness remains obscure.