Objective: To determine whether the long-term reduction of plasma ornithine levels by way of an arginine-restricted diet in patients with gyrate atrophy will slow the progression of this chorioretinal degeneration.
Design: Natural history study of 2 pairs of siblings with gyrate atrophy treated with an arginine-restricted diet.
Main outcome measures: Fundus photography and electrophysical and psychophysical retinal function tests.
Results: After 16 to 17 years of receiving an arginine-restricted diet, the younger sibling in each pair, who was prescribed the diet at an earlier age than the older sibling, demonstrated a slower progression of lesions compared with the older sibling.
Conclusions: If started at an early age, long-term substantial reduction of plasma ornithine levels may appreciably slow the progression of the chorioretinal lesions and, to a lesser extent, the progressive loss of retinal function in patients with gyrate atrophy.