Night blindness and Crohn's disease.

Signs of malnutrition are common clinical features in Crohn's disease; and bowel resection, commonly needed in these cases, can aggravate malnutrition. These patients are at risk of developing vitamin A deficiency, which can lead to night blindness. We present a 60-year-old male, with history of Crohn's disease and multiple resections for strictures and fistulas leading to short bowel syndrome, with progressive bilateral loss of night vision (nyctalopia). Serum vitamin A level was markedly depleted (11 µg/dL, reference 20-120 µg/dL), and full-field electroretinogram testing demonstrated extinguished scotopic (rod function) responses and decreased amplitudes of photopic responses on 30 Hz flicker (cone function). He was started on vitamin A supplementation (initially intramuscular). His vitamin A level was back to normal (78 µg/dL), and night vision problems subjectively improved. Patients with Crohn's disease should be inquired about night vision problems. The presence of nyctalopia should prompt vitamin A level measurement and ophthalmology referral for further evaluation.