Correlation between retinal vessel density and retinal layer thickness in eyes with proliferative diabetic retinopathy

Abstract

Purpose : To investigate the correlation between retinal capillary vessel density (VD) and retinal layer thickness (RT) in the macular region of eyes with proliferative diabetic retinopathy (PDR) and no macular edema

Methods : 40 eyes of 40 subjects were enrolled in this prospective,randomised clinical trial (RECOVERY:NCT02863354) and 35 eyes with OCT angiography (OCTA) were included in this analysis. All eyes had treatment naive PDR with no macular edema. All subjects underwent spectral-domain optical coherence tomography (SD-OCT) [Spectralis Heidelberg Retinal Angiogram (HRA+OCT) scans (20 x 20 degrees; 512 x 97; ART = 5)] and OCTA using the RTVue-XR 100 Avanti (Optovue, Inc). Baseline (pre-treatment) images were included in the analysis. Superficial (nerve fiber plus ganglion cell layers) and deep (inner plexiform, inner nuclear, & outer plexiform layers) inner retinal layer thickness values were generated after manual segmentation of all the B scans using custom reading center software (3D-OCTOR) by certified graders. Capillary VD was generated (superficial and deep) using RTVue review software. Both RT and VD measurements were generated within the entire scan area for both superficial and deep retinal layers. A bivariate correlation analysis (Spearman’s) was performed between the corresponding RT values and the VD for the superficial and deep layers, respectively. Statistical analysis was performed using SPSS, a p value of < 0.05 was considered as statistically significant.

Results : Thirty five eyes of 35 subjects (3 males, 32 females) were included in this analysis. The thickness measurements (microns), in mean + SD were as follows: superficial RT (SRT), 78.7 + 13.3; deep RT (DRT), 106.7 + 14.7 and total RT, 286.2 + 27.9. The corresponding capillary perfusion values (%), in mean + SD were: superficial VD (SVD), 42 + 4 and deep VD (DVD), 49 + 4. There was no significant correlation between SRT and SVD (r = 0.29, p = 0.24); DRT and DVD (r = 0.41, p = 0.09; TRT and SVC (r = 0.18, p = 0.48); TRT and DVD (r = 0.25, p = 0.33).

Conclusions : No correlation was observed between retinal thickness and capillary perfusion in either the superficial or deep inner retinal layers in eyes with treatment naive PDR and no macular edema. This lack of correlation suggests that other compensatory mechanisms may influence retinal thickness in these eyes with PDR, despite alterations in perfusion.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.