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Xiangrong Kong, Rupert Wolfgang Strauss, Beatriz Munoz, Ann-Margret Ervin, Artur V Cideciyan, Michel Michaelides, Mohamed Ahmed, Janet Cheetham, Sheila West, Hendrik P Scholl; Visual acuity loss during two years in Stargardt Disease: The ProgStar Study. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4647.
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Prior studies of Stargardt disease were often based on retrospective chart reviews where data quality may be limited due to inconsistency in testing procedures. Using prospective data from the ProgStar study, we estimated VA loss over two years and determined associations with demographic and clinical factors.
259 molecularly (ABCA4 gene mutations) confirmed Stargardt disease type 1 (STGD1) patients (489 study eyes) were enrolled from nine sites, and were followed every 6 months for up to 24 months. Monocular best corrected VA was measured using the ETDRS protocol. Linear models with generalized estimating equations were used to compare baseline VA (in LogMAR) by participant characteristics. With available longitudinal data up to 24 months, linear mixed effects models were used to estimate the VA loss rate.
At baseline, the median age was 31 (range 7-69) years, and 54% were female. Median age of symptom onset was 19 (range 4-64) years, and median duration of symptoms was 9 (range 0-55) years. There were 29 (11%) current smokers, and 37 (14%) reported vitamin-A supplementation use. The mean baseline VA was 0.78 LogMAR (SD=0.32). RPE pigmentation, flecks outside the arcades, juvenile symptom onset (onset age≤18 years), and longer symptom duration since symptom onset was associated with worse VA (p<.05). VA was not significantly associated with smoking or vitamin-A use. Over the 24 months, the overall rate of VA loss was 0.01 LogMAR (i.e. 0.1 line)/year (p=.004). The rate was 0.03 (p=.03) and 0.1 (p=.002) LogMAR/year in eyes with initial VA better than 20/70 and in eyes with VA between 20/70 and 20/200, respectively. In eyes with initial VA worse than 20/200, VA improved at a rate of 0.01 LogMAR/year (p=.02). Symptom duration was associated with VA change rate (p=.001). Age of symptom onset, presence of flecks outside the arcades, RPE pigmentation, smoking, or vitamin A use was not associated with VA change rate. From baseline to the 24-month visit, 12 eyes (3%) lost ≥3 lines, and 57 eyes (16%) lost ≥1 line. For eyes with initial VA better than 20/200 (N=282), 27 eyes (9.6%) had VA worse than 20/200 at 24 months.
Overall, VA declined during the 24 months at a statistically significant but clinically small rate. The VA change rate depended on initial VA. A small but statistically significant improvement of VA was found in eyes with severe impairment at baseline.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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