Six patients with bradyopsia (slow vision) - Clinical features and course of the disease

Objective: Recently, it was discovered that subjects who showed a prolonged response suppression on their electroretinogram (ERG) and had symptoms of photophobia, problems adjusting to bright light, and difficulties seeing moving objects shared a mutation in the RGS9 (regulator of G-protein signaling 9) gene that is involved in the deactivation of photoreceptor responses. The disorder was termed bradyopsia (slow vision). This paper reports the clinical presentation and long-term follow-up of 6 bradyopsia patients. Design: Retrospective observational case series with a follow-up ranging from 6 to 30 years. Participants: Six patients with a homozygous mutation in the RGS9 gene. Methods: Clinical symptoms and signs were compared between the subjects and between their visits over time. Main Outcome Measures: Symptoms, visual acuity (VA), ocular findings, visual fields, dark-adaptation tests, color tests, fluorescein angiography, and ERG findings. Results: Data showed a consistency in the individual symptoms and ERG recordings, but an extreme variation in VA between visits. Beside some irregularities in the macula in some patients, no other related eye abnormalities were seen. The low-to-subnormal VA varied with background luminance and typically increased by 2 to 3 lines when pinholes were used. Dark-adaptation tests, color tests, and fluorescein angiography were normal. Visual field tests showed a minor diffuse sensitivity loss. No progressive changes were seen over time. Conclusions: No signs of progression were noted in the 6 bradyopsia patients. Photophobia, impaired movement perception, variable reduced VA that improved with the use of pinholes and ERG abnormalities were typical for the disease.