Changes in choroidal vasculature predict visual outcomes in Stargardt disease

Abstract

Purpose : Vascular status of the choroid in ABCA4-related Stargardt disease (STGD1) remains unclear. We hypothesized that alterations in choroidal vasculature contribute to changes in visual acuity. In this analysis, we evaluated the morphofunctional relationship between choroid and visual acuity in a Stargardt disease cohort.

Methods : Enhanced depth imaging (EDI) optical coherence tomography (OCT) scans and best-corrected visual acuity (BCVA) were collected at baseline, six, and 12 month follow-up visits from 37 eyes of 37 subjects from the prospective multicenter “Natural History of Progression of Stargardt Disease” (ProgStar) study. Various choroidal parameters at the sub-fovea including choroidal area (CA), luminal area (LA) and choroidal vascularity index (CVI: proportion of LA to CA) were computed using a previously reported image binarization technique (Figure 1). Repeated measures ANOVA was used to study the changes in vision and choroid during subsequent visits. The correlation between choroidal parameters and BCVA was assessed using Pearson and multiple linear regression analysis.

Results : Results are expressed as mean ± standard deviation. The mean age of study subjects was 33 ± 14 years (range: 11-67), and 17 were female. BCVA was 0.82 ± 0.32 logMAR with spherical equivalent (SE) of refractive error of -3.02 ± 2.69 diopters. The mean CA, LA and CVI were 0.76 ± 0.21 mm² (range: 0.34-1.26), 0.49 ± 0.14 mm² (range: 0.22-0.80) and 0.64 ± 0.03 (0.56-0.70), respectively. CVI was negatively correlated (r = -0.44, p = 0.01) with logMAR equivalent BCVA, and positively correlated with LA (r = 0.34, p = 0.04), indicating worse visual acuity was associated with reduced choroidal vasculature. Age (r = -0.15, p = 0.38), SE (r = -0.07, p = 0.69) and CA (r = 0.21, p = 0.22) did not show a significant correlation with CVI. Multiple linear regression analysis also demonstrated CVI as a significant (p = 0.01) predictor of BCVA. The choroidal parameters and BCVA did not significantly change between follow-up visits.

Conclusions : The vascular component of the choroid appears to be related to visual function in Stargardt disease. Further replicative studies are required to confirm this relationship and better define the pathophysiologic mechanisms.

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

 

Figure 1. EDI-OCT B-scan from a Stargardt patient’s eye. (A) Raw OCT B-scan. (B) OCT B-scan image following binarization; CA (within red) and LA (dark pixels within CA).