Assessment of visual function in patients with gyrate atrophy who are considered candidates for gene replacement

Objective: To assess the course of change of visual function outcome variables in 5 patients with gyrate atrophy before a gene replacement therapy clinical trial. Methods: The outcome variables selected were visual field sensitivity and electroretinogram amplitude. The course of change of these outcome variables was determined by calculation of their half-lives. Results: In the 4 to 6 years during which each patient was followed up for this study, median visual field half-lives were 17.0 years (static perimetry) and 11.4 years (kinetic perimetry). Median electroretinogram half-lives were 16.0 years (maximal response) and 10.7 years (flicker response). Conclusions: The course of the decline of visual function outcome variables is frequently slow. Thus, a long-term clinical trial would be required to assess the efficacy of the intervention in the preservation of visual function.