Abstract
Purpose :
A subset of Retinitis Pigmentosa (RP) patients exhibit a perifoveal Ring of hyper-AutoFluorescence (RAF) that appears to demarcate normal and dystrophic retina as determined by Fundus AutoFluorescence (FAF) and Optical Coherence Tomography (OCT). We performed a cross-sectional OCT-Angiography (OCT-A) study to analyze macular Vessel Density (VD) of Superficial and Deep Retinal (SR and DR) vascular complexes in RP patients with RAF to determine if the microvascular changes reported in previous studies follow the same demarcation.
Methods :
Macular OCT-A images (3mm×3mm) were acquired in 15 eyes of 8 normal individuals and 15 eyes of 9 RP patients with RAF. En face OCT-A images of retinal vasculature (superficial and deep vascular complexes) were registered to FAF images using Adobe Photoshop CC (Adobe Inc, San Jose, CA). VD was calculated in ImageJ (NIH, Bethesda, MD) as the ratio of pixels occupied by the vessels to the total number of pixels per image, excluding the foveal avascular zone. Macular VD in SR and DR vascular complexes was calculated in 3 x 3 mm2 OCT-A images of controls and RP patients and in the area within the RAF in RP patients.
Results :
On 3 x 3 mm2 OCT-A images, RP patients (mean age 42 years; males, 55.6%) had a statistically significant lower mean VD in SR and DR vascular complexes than controls (mean age 24.6 years; males, 37.5%) (p = 0.00) (Table 1). No significant difference was found in SR and DR vascular complexes when VD within RAF was compared with total VD in RP patients (Table 2).
Conclusions :
Patients with RP had a lower VD in the SR and DR, which was consistent within RAF suggesting that the vascular changes are global across the normal and abnormal areas imaged by OCT-A. The variation in VD in different layers may represent a novel staging biomarker but a longitudinal study of longer cohorts is needed to validate this hypothesis.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.