Abstract
Purpose :
The DRCR Retina Network Protocol S trial was a non-inferiority study that compared ranibizumab (RBZ) to PRP in eyes with high-risk PDR. To better understand the long-term effects of anti-VEGF therapy, we performed a post-hoc evaluation of retinal vasculature in PDR eyes treated with RBZ versus PRP.
Methods :
Fundus photographs of study eyes were evaluated for retinal vessel caliber at Baseline (BL), 2-Year (Y2), and 5-Year (Y5) time points. The Integrative Vessel Analysis (IVAN) software was used to measure Central Retinal Artery/Vein Equivalents (CRAE/CRVE) and the arteriovenous ratio (AVR) of vessels at 1 disc diameter from the optic nerve. Changes in CRAE, CRVE, and AVR over the 3 time points were analyzed between the RBZ and PRP groups using mixed linear regression models. Sensitivity analyses included censored eyes in each randomization group that received the alternate treatment.
Results :
107 eyes (83 participants) with gradable images for all 3 timepoints were analyzed: 48 eyes (35 participants) in the RBZ group and 59 eyes (48 participants) in PRP group. CRAE decreased significantly more in the PRP versus (vs) RBZ arm at Y2 (mean (SD) = -12 (17) µm vs. -2 (12) µm p=0.003), and there was a trend towards greater decrease in the RBZ arm between Y2 and Y5 (-1 (17) µm vs. -8 (18) µm, p = 0.13) with no difference between the groups at Y5 (-13 (18) vs. -9 (17), p = 0.22). CRVE decreased consistently in the PRP vs. RBZ arm at Y2 (-19 (25) vs. -14 (22), p = 0.26), with a larger decrease in the PRP arm at Y5 (-28 (27) µm vs. -18 (21) µm, p = 0.01). However, this decrease was not sustained following sensitivity analysis. In the RBZ group, the mean (SD) number of injections was 22.0 (11.4) at Y5 with no difference between BL/Y2 and Y2/Y5. In the final models, inclusive of ocular factors, BL demographics and randomization stratification factors, the only additional factor associated with changes in CRAE and CRVE was BL diabetic retinopathy.
Conclusions :
Decreases in arteriolar and venular caliber were seen over 5 years in both the RBZ and PRP groups. While most of the arteriolar narrowing occurred within the first 2 years for the PRP group, it occurred after 2 years in the RBZ group, suggesting that these treatments may affect the retinal vasculature at differential rates.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.