Visual results of a long-term trial of a low-arginine diet in gyrate atrophy of choroid and retina.

Visual function has been serially assessed in two gyrate atrophy patients who have had long-term reduction of plasma ornithine concentrations by a low-arginine diet. One patient demonstrated subjective and objective improvement after 15 months of treatment. In addition to improvements in dark adaptation thresholds, enlargement of visual fields, and a more normal electroretinogram, there was marked improvement in cone function as measured by color vision. There has been no change noted in the second patient. These results suggest that reduction of plasma ornithine may be beneficial in gyrate atrophy patients and that the high ornithine concentrations characteristic of this disorder play some role in the pathophysiology.