Abstract
Purpose :
Retinitis pigmentosa (RP) is an inherited neurodegenerative disease. The death of rod photoreceptors leads secondary cone death. Underlying mechanisms of disease progression remains unknown. To better understand the pathogenesis of RP, investigate the structure using latest high-resolution imaging technology is essential. This study was designed to evaluate the structural characteristics and microvasculature changes in corresponding retinal area using multiple imaging methods.
Methods :
We imaged 35 eyes from 20 RP patients using flood-illuminated AO camera (Imagine Eyes, Orsay, France) and OCTA (RTVue-XR Avanti; Optovue, Inc, Fremont, CA). Macular AO images covering an area of 2.4-mm diameter (8°) concentric annular zone was subdivided into six annular rings. Cone density (cells/mm2) was measured in total annular zone used a custom automated algorithm. Macular vascular density (VD) in superficial capillary plexus (SCP) and deep capillary plexus (DCP) were assessed using the built-in software of OCTA instrument. In addition, we investigated the correlation of these parameters with logMAR visual acuity and mean cone density in all study eyes.
Results :
The mean parafoveal cone density (C6) was significantly lower in RP patients group compared to normal group (P < 0.001). Furthermore, each annuli area (C1 to C5) separately revealed lower average cone densities in RP patients group compared to normal group (P < 0.001). Mean VD was lower in RP eyes compared with control eyes in both superficial (P < 0.001) and deep (P < 0.001) networks. In all eyes, there was a statistically significant negative correlation between logMAR visual acuity and the vascular density in both superficial (r = -0.35; P =0.02) and deep (r = -0.47; P =0.001) networks. The mean cone density had no correlation with superficial vessel density but had a moderate positive correlation with deep vessel density (r = 0.424; P =0.004). AO images revealed a distinct mosaics pattern of RPE cells in regions where it appeared that cones were missing. It indicated morphological changes of cone photoreceptor.
Conclusions :
There is a significant cone loss accompanied by degenerative changes in retinal capillary plexus in patients with RP. High-resolution image technologies show great potential in monitoring disease progression and identifying parameters that affect visual function.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.