ACQUIRED UNILATERAL NIGHT BLINDNESS ASSOCIATED WITH A NEGATIVE ELECTRORETINOGRAM WAVE-FORM

Purpose: The authors performed clinical, electrophysiologic, psychophy sical, and immunologic studies in a patient who presented with an acqu ired night blindness in one eye to better define the clinical and func tional changes in this rare disorder. Methods: In addition to an ophth almologic examination, the patient underwent the measurement of electr oretinogram responses, dark-adapted thresholds using a Tubingen perime ter (Oculus, Tubingen, Germany), color vision assessment, kinetic visu al-field testing using a Goldmann perimeter, and immunologic testing t o determine if the serum contained autoantibodies to retinal bipolar c ells. Results: Fundus examination showed no clinically apparent abnorm ality 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 thr esholds in the right eye were normal centrally and slightly elevated i n the far periphery. Immunologic testing did not show circulating auto antibodies to retinal cells. Conclusions: The patient examined in this study showed phenotypic similarities to patients with congenital stat ionary night blindness and to patients with an acquired form of night blindness associated with cutaneous melanoma (MAR syndrome). The elect roretinogram 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 b lindness remains obscure.