Authors: Collier (Shangjun) Jiang, Netan Choudhry

Author Disclosure Block: C. Jiang: None. N. Choudhry: Consultant; Topcon. Topcon had no role in the study design, collection, analysis and interpretation of data in this report.

Abstract Body:

Purpose: Retinitis pigmentosa (RP) is a group of inherited retinal diseases characterized by progressive degeneration of photoreceptor cells. The ring of hyperautofluorescence is a well-recognized feature in retinitis pigmentosa (RP). These areas of increased autofluorescence correspond to an increase of lipofuscin in the retina pigment epithelium, which indicates increased metabolic activity and oxidative stress. However, little is known about the relationship between the area of hyperautofluorescence and vascular perfusion parameters as obtained by optical coherence tomography angiography (OCT-A).
Study Design: In this retrospective, cross-sectional study, we measured the area of the hyperautofluoresent ring in patients with RP, to determine correlation with visual acuity, foveal avascular zone (FAZ) size, and retinal capillary perfusion density (CPD).
Methods: 9 patients with bilateral RP were identified using fundus autofluorescence (AF) (California; Optos, Dunfermline, Scotland), totaling 18 eyes. Patient medial records were reviewed to obtain demographic and visual acuity data. Spectral domain optical coherence tomography angiography (OCT-A) (AngioVue; Optovue, Fremont, CA) was used to assess retinal vascular perfusion and calculate CPD in the superficial capillary plexus (SCP) and the deep capillary plexus (DCP) using both a 3.0 mm x 3.0 mm strategy, and a 6.0 mm x 6.0 mm strategy. In addition, OCT-A was used to measure and calculate the size of FAZ. ImageJ software (version 1.51k) was used to measure the area of the hyperautofluoresent ring in each eye with RP. Pearson correlation coefficients were calculated to determine the strength of linear relationship between hyperautofluoresent ring size and the following variables: visual acuity, SCP parafoveal CPD, DCP parafoveal CPD, and FAZ area. Regression analysis was performed to determine if the correlation between two measured variables were statistically significant.
Results: Hyperautofluoresent ring area was highly concordant between the right and left eyes in each patient (R = 0.99, P < 0.001). While hyperautofluoresent ring size and FAZ size were inversely correlated, the results were not significant (R = -0.36, P = 0.14). Visual acuity was not correlated with hyperautofluoresent ring size (R = 0.24, P = 0.33). There was no correlation between hyperautofluoresent ring size and parafoveal CPD using the 3.0 mm x 3.0 mm strategy or 6.0 x 6.0 mm strategy in the SCP (R = 0.08, R = 0.19; respectively), or DCP (R = 0.28, R = 0.27; respectively).
Conclusions: Assessing the hyperautofluoresent ring in RP is an important clinical tool for determining disease severity and progression. Previous studies have indicated that RP eyes had a significantly lower SCP and DCP parafoveal flow density compared to age-matched controls. Additionally, disease progression in RP has been shown to correlate with constriction in hyperautofluoresent ring size and decrease in visual function. While hyperautofluoresent ring size may be negatively associated with FAZ size, it is not a reliable predictor of visual acuity or retinal capillary perfusion density.