Serial ERG monitoring of response to therapy in vitamin A deficiency related night blindness.

Two male patients with known systemic disorders who presented with complaints of nyctalopia underwent a complete ophthalmic examination including electrophysiological evaluation and serum vitamin A (retinol) levels. A significant vitamin A deficiency was detected, supplementation started and repeat electroretinogram (ERG) testing was carried out to monitor the timeline of recovery. Restoration of rod and generalised cone function was rapid within the first week of receiving treatment and near normal recovery was seen after 1 month of supplementation. Serial monitoring of ERG changes in vitamin A deficiency (VAD) associated night blindness plays an important role to demonstrate functional recovery post-treatment. The different effects of VAD on rod and cone function, and their rate of recovery, may reflect differences in the visual cycle between the two photoreceptors. We report the serial ERG changes in VAD related night blindness secondary to intestinal lipofuscinosis and liver cirrhosis in two patients.