Mohamed Ahmed

Visual Acuity Change Over 24 Months and its Association With Foveal Phenotype and Genotype in Individuals With Stargardt Disease: ProgStar Study Report No. 10

Importance Limited data from prospective studies are available to understand the natural history of ABCA4-related Stargardt disease (STGD1). Such data are important for determining appropriate outcome measures for future STGD1 trials. Objective To estimate the rate of loss of best-corrected visual acuity (BCVA) during 2 years and to estimate the associations of BCVA loss with foveal phenotype and genotype in patients with STGD1. Design, Setting, and Participants This multicenter prospective cohort study included 259 participants (489 study eyes) with molecularly confirmed STGD1 who were 6 years or older. The participants were enrolled at 9 centers in the United States and Europe and were followed up every 6 months for 2 years. Exposures Baseline BCVA and presence and type of foveal lesion (determined via fundus autofluorescence images) and genotype (classified into 4 groups based on the number and pathogenicity of ABCA4 mutations). Main Outcomes and Measures Rate of BCVA change per year. Results The mean (SD) age was 33 (15) years. Of 259 the participants, 141 (54%) were female, and 222 (85%) were white. The overall rate of BCVA loss was 0.55 (95% CI, 0.20-0.90) letters per year during the 2 years. Eyes with baseline BCVA worse than 20/200 showed an improvement of 0.65 (95% CI, 0.1-1.2) letters per year. At baseline, the mean BCVA for eyes without foveal lesion was 20/32, and their BCVA change rate over time was 0.1 (95% CI, −1.2 to 1.35) letters per year (P = .89). Eyes with a foveal lesion but having BCVA of 20/70 or better at baseline lost BCVA at a rate of 3 (95% CI, 1.5-4.4) letters per year (P < .001). Genotype was neither associated with baseline BCVA nor with the rate of BCVA change during the follow-up. Conclusions and Relevance A clinically small BCVA loss was observed during 2 years, and the change rate varied depending on baseline BCVA. Eyes without lesion in the fovea had better BCVA at baseline and showed minimal change of BCVA throughout 2 years. Eyes with no or modest acuity impairment but with a foveal lesion at baseline had the fastest loss rate. For trials of STGD1 with 2 years of duration, it may be difficult to show efficacy using BCVA as an end point owing to its slow rate of change over this time.

Scotopic Microperimetric Assessment of Rod Function in Stargardt Disease (SMART) Study: Design and Baseline Characteristics (Report No. 1)

Purpose: To describe the study design and characteristics at first visit of participants in the longitudinal Scotopic Microperimetric Assessment of Rod Function in Stargardt Disease (SMART) study. Methods: Scotopic microperimetry (sMP) was performed in one designated study eye in a subset of participants with molecularly proven ABCA4-associated Stargardt disease (STGD1) enrolled in a multicenter natural history study (ProgStar). Study visits were every 6 months over a period ranging from 6 to 24 months, and also included fundus autofluorescence (FAF). Results: SMART enrolled 118 participants (118 eyes). At the first visit of SMART, the mean sensitivity in mesopic microperimetry was 11.48 (±5.05; range 0.00–19.88) dB and in sMP 11.25 (±5.26; 0–19.25) dB. For FAF, all eyes had a lesion of decreased autofluorescence (mean lesion size 3.62 [±3.48; 0.10–21.46] mm2), and a total of 76 eyes (65.5%) had a lesion of definitely decreased autofluorescence with a mean lesion size of 3.46 (±3.60; 0.21–21.46) mm2. Conclusions: Rod function is impaired in STGD1 and can be assessed by sMP. Testing rod function may serve as a potential outcome measure for future clinical treatment trials. This is evaluated in the SMART study.

The Progression of the Stargardt Disease Type 4 (ProgStar-4) Study: Design and Baseline Characteristics (ProgStar-4 Report No. 1)

Background/Aims: To describe the design and baseline characteristics of patients enrolled in the multicenter, prospective natural history study of Stargardt disease type 4. Methods: Fifteen eligible patients aged 6 years and older at baseline, harboring disease-causing variants in the PROM1 gene, and with specified ocular lesions were enrolled. They were examined at baseline using a standard protocol, with 6 monthly follow-up visits for a 2-year period including best-corrected ETDRS visual acuity, spectral-domain optical coherence tomography, fundus autofluorescence (FAF), mesopic and scotopic microperimetry (MP). Areas of definitely decreased FAF (DDAF) and questionably decreased FAF were outlined and quantified on FAF images. Results: Amongst the 15 patients (29 eyes) that were enrolled at 5 centers in the USA and Europe, 10 eyes (34.5%) had areas of DDAF with an average lesion area of 3.2 ± 3.5 mm2 (range 0.36–10.39 mm2) at baseline. The mean retinal sensitivity of the posterior pole derived from mesopic MP was 8.8 ± 5.8 dB. Conclusions: Data on disease progression in PROM1-related retinopathy from this study will contribute to the characterization of the natural history of disease and the exploration of the utility of several modalities to track progression and therefore to potentially be used in future interventional clinical trials.