Clinical phenotype as a prognostic factor in Stargardt disease.

Abstract

To determine the prognostic significance of widespread flecks, described as fundus flavimaculatus, in patients with Stargardt disease. Historical cohort study. Patients with Stargardt disease were identified by searching preexisting databases at the University of Iowa and Oregon Health Sciences University. The medical records of these patients were evaluated for the validity of the diagnosis, initial and final visual acuity, length of follow-up, and initial and final phenotype. Phenotype was graded as I, II, or III on the basis of the distribution of flecks and the extent of atrophy. The relationship between final visual acuity and final clinical appearance (phenotype I versus II versus III) was evaluated controlling for length of follow-up and age using a Cochran-Mantel-Haenszel test. The clinical progression of visual acuity loss for each phenotype was analyzed using life tables and Kaplan-Meier survival analysis for age and length of follow-up effects. A total of 214 patients were confirmed to have Stargardt disease; 131 patients were seen at multiple visits. Eighty-two patients were identified with phenotype I, 62 with phenotype II, and 70 with phenotype III. The final visual outcome was significantly better for patients whose ophthalmoscopic abnormalities were limited to the macula (phenotype I): 80 of 82 patients with phenotype I (97.6%) maintained 20/200 or better visual acuity in at least one eye as compared to 40/62 (64.5%) patients with phenotype II and 13/70 (18.6%) patients with phenotype III (P < 0.0001). Survival analysis showed a similarly significant difference in the survival probabilities (likelihood of maintaining 20/200 or better vision) for the three phenotypes considered over age and over follow-up length (P < 0.0001), with phenotypes II and III demonstrating significantly more deterioration in vision over time. The presence of midperipheral flecks, especially early in life, carries a poorer visual prognosis for patients with Stargardt disease than when disease is limited to the macula. The development of midperipheral flecks is an indicator of more extensive fundus involvement and thus poorer long-term visual prognosis.