Purpose : To evaluate the incidence of Leber’s Congenital Amaurosis (LCA) in low vision children referred to electrophysiology ward of Farabi Eye Hospital , and review the clinical features of disease and Electroretiongraphy (ERG) test values to confirm the diagnosis and severity of the disease in Iran .

Design: Prospective observational case series

Methods : Two-hundred and fifteen cases of low vision infants and young children were referred to electrophysiology ward of Farabi Eye Hospital during 18 months. Clinical LCA diagnosis was made and ERG tests were done and LCA diagnosis was confirmed. The symptoms, signs and the results of eye examination and ERG findings were recorded.

Results : The mean age of the patients was 27.43 (range, 1-120 months). Among low vision patients fourteen percent of patients had LCA. Fifty-four percent of the patients were female. Nystagmus and low vision were the two most common clinical manifestations of these patients. Hyperopia was the main refractive error (54.80%) and mild abnormalities in fundus examinations were found in 67.70% of cases. In nearly 90% of cases consanguinity was found. ERG was flat or unrecordable in more than 90% of cases, but in less than 10% of cases with recordable curves, severe decrease in amplitude of waves was encountered. ERG confirmed LCA diagnosis in 31 out of 37 patients (positive predictive value of 83.7%).

Conclusion : The incidence of LCA in low vision children is similar to other studies. ERG helped in confirmation of presence or absence of overall retinal dysfunction in the majority ³¹/₃₇ (83.7%) of LCA patients. It can differentiate these cases from other cases with poor vision in infantile age but genetic testing is recommended.