Visual acuity in Stargardt disease patients after age 40

Abstract

Purpose : In order to better define visual loss in Stargardt disease patients later in life, we investigated the most recent visual acuity in a cohort of Stargardt disease patients beyond 40 years of life.

Methods : The most recent best corrected visual acuities (BCVA, Snellen or Feinbloom Low Vision Chart) in the better-seeing eye of 225 patients with Stargardt disease over 40 years of age were recorded in this retrospective study. Also included in the analysis were the age of subjective onset for symptoms and duration of symptoms (“duration”=age-onset). The Mann-Whitney U test was used to compare differences between groups (BCVA), while the Spearman rank-order correlation was used to measure associations between continuous variables (BCVA versus age, onset, and duration of symptoms).

Results : The median age of the Stargardt disease patients was 53.1 years, with an interquartile range (IQR) of 46.9-61.3 and a range of 41 to 88 years. The median BCVA of all patients showed a bimodal distribution (shown in Figure 1), with a median BCVA of 1.00 logMAR (20/200 Snellen, IQR 0.22 to 1.10 logMAR). Twenty-five patients (11.1%) had worse than 20/400 vision, and ten patients (4.4%) had worse than 20/800 vision. In the subset of 19 patients with subjective onset of age 10 or younger, the median BCVA was 1.30 logMAR (20/400, IQR 1.00 to 1.60). Eleven of these 19 patients had BCVA of 20/400 or better, four were between 20/500 and 20/800, and the remaining four had BCVA worse than 20/800. There was only a modest correlation of BCVA with age (r_s=0.17, P=0.01), but there were stronger correlations between BCVA and both subjective onset (r_s=-0.62, P<0.001) and duration of symptoms (r_s=0.7, P<0.001).

Conclusions : Although many Stargardt disease patients lose visual acuity to the 20/200-20/400 range, and some lose visual acuity beyond 20/400, only a small number of our patients were found to have “counting fingers” vision or worse, even with early onset of symptoms. These numbers will be valuable in counseling Stargardt disease patients on visual loss and could have value in planning treatment trials.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

 

Figure 1: Histogram of best corrected visual acuity (BCVA) in 225 Stargardt disease patients between 41 and 88 years of age. Note the bimodal distribution of visual acuity, with 38% of patients falling in the 20/15 to 20/50 range and 44% falling in the 20/125 to 20/400 range.