Session Title: Free Paper Session 12: Imaging I
Session Date/Time: Friday 08/09/2017 | 14:30-16:00
Paper Time: 15:06
Venue: Room 111
First Author: : T.Alabduljalil CANADA
Co Author(s): : R. Patel A. Alqahtani S. Gao R. Weleber M. Pennesi P. Yang
To study imaging of the outer retina, RPE and choriocapillaris (CC) in Stargardt disease using OCT-Angiography (OCT-A) and en face OCT.
This is a cross-sectional observational case series of 23 cases with Stargardt disease. This study was performed at Casey Eye Institute, Portland, OR, USA.
After obtaining an informed consent, clinical exam and multimodal imaging was performed including en face OCT, OCT-A, and fundus autofluorescence (FAF) for each patient. OCT slabs were manually adjusted in each case to best capture the IS/OS and RPE layers using custom Matlab software. To quantify loss, three experienced masked graders measured the defect area of the IS/OS and RPE in 6x6mm en face OCT image of each respective layer. The split-spectrum amplitude-decorrelation angiography (SSADA) algorithm was employed to quantify the choriocapillaris vascular density (CCVD) for the 6x6 mm OCT-A image. Graphpad Prism (v.7.0) was used to perform non-parametric linear regression analysis.
The mean age at imaging was 37 (range 13-62, SD 17) years. There was a high degree of agreement between the graders as measured using Spearman r correlation (e.g. RPE loss for TA vs. AAA: r= 0.96 (95% CI 0.90 – 0.98, <0.0001). The areas of loss within the right and left eye were very symmetric (r2 =0.97 for RPE; r2 =0.98 for IS/OS). In all eyes, the area of loss in the IS/OS was larger than that of the RPE by a ratio of 1.76:1 (r2 =0.939, p <0.0001). The CCVD showed a trend toward decline with more IS/OS loss (r2 =0.69, p<0.0001) and with more RPE loss (r2 =0.57, p<0.0001).
We show here for the first time, to our knowledge, quantitative evidence that photoreceptor degeneration in Stargardt disease likely precedes that of RPE, both of which correlate with CC density. As retinal gene therapy and other therapeutic strategies for Stargardt disease evolve, quantitative analysis of en face OCT and OCT-A may be potentially useful as a tool for future clinical trials.