Long term follow-up of Stargardt dystrophy

Abstract

Purpose : To investigate the progression rate of patients with Stargardt dystrophy (STGD) in the longitudinal follow-up from 1 to 18 yrs (mean 9.2 yrs).

Methods : 33 patients with STGD aged 8 yrs and older were enrolled (26 F, 7 M; mean age first visit, 24.7 yrs; mean age last visit, 33.9 yrs). Patients were recruited based on typical clinical picture and genetic analysis. Snellen VA, qualitative and quantitative analysis of autofluorescence (AF) images (Heidelberg Engineering, Germany) and electrophysiology (ERG) were done. Areas of definitely decreased autofluorescence (DDAF) and questionably decreased autofluorescence (QDAF) were measured (ImageJ, 1.52r version) in 13 out of 33 patients, and progression rates per year were calculated. Based on electrophysiological abnormalities, patients (28/33) were classified into group 1 with only macular involvement, group 2 with abnormal cone responses and group 3 with abnormal scotopic and photopic responses. Right patients' eyes were taken for analysis.

Results : Mean VA was 0.26±0.29 SD at baseline and 0.11±0.11 SD at the end. Qualitative analysis of AF at baseline and last exam showed: flecks (63.6%;75.7%), flecks beyond the arcades (45.4%;60.6%), increased autofluorescence at DDAF lesion edge (27.3%;27.3%), background heterogeneity (30.3%;48.5%), and peripapillary sparing (94.0%;88.0%), respectively. AF images from a subset of 13 patients (11 F, 2 M; mean age, 31.3 yrs; mean follow-up 8.4 yrs) were further analysed. 12 of 13 patients had DDAF (mean lesion size 1.74 mm² at baseline), and combined DDAF and QDAF (mean lesion size 4.67 mm² at baseline). The estimated progression per year was calculated. The mean progression of DDAF was 0.77 mm² per year, and the total area of DDAF and QDAF was 1.43 mm² per year. At the beginning of the follow-up, ERG was done in 28 out of 33 patients; 15 were classified only as macular involvement, 7 with abnormal cone responses and 6 with abnormal scotopic and photopic responses. Patients in the last group had a tendency to progress quicker.

Conclusions : Area of DDAF was progressing 0.77 mm² per year, which is in accordance with larger multicenter studies. A combination of electrophysiology with qualitative and quantitative analysis of AF images is an important tool for better understanding of the clinical presentation and progression of the disease. DDAF and combination of DDAF and QDAF may serve as an outcome measure for future clinical trials.

This is a 2020 ARVO Annual Meeting abstract.