Long-Term Effects of Anti-VEGF Therapy versus Panretinal Photocoagulation on Retinal Vessel Caliber in Eyes with Proliferative Diabetic Retinopathy.

PURPOSE

To evaluate the long-term effects of ranibizumab compared with panretinal photocoagulation (PRP) on retinal vasculature in eyes with proliferative diabetic retinopathy (PDR).

DESIGN

Post hoc analysis of DRCR Retina Network Protocol S randomized clinical trial.

PARTICIPANTS

Adults with type 1 or 2 diabetes and PDR in at least 1 eye.

METHODS

Integrative Vessel Analysis software was used to measure central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE) of vessels at 1 disc diameter from the optic nerve edge on fundus photographs at baseline, 2 and 5 years for study eyes randomized to ranibizumab or PRP treatment for PDR. Changes in CRAE and CRVE were analyzed using mixed linear regression models with multivariable adjustments.

MAIN OUTCOME MEASURES

Mean change in CRAE and CRVE from baseline to 2 and 5 years.

RESULTS

Data from 107 eyes (90 participants) in the ranibizumab (n = 48) and PRP group (n = 59) were analyzed. For the ranibizumab versus PRP groups, CRAE decreased by a mean of 2 versus 12 μm at 2 years (mean difference, 10 μm; 95% confidence interval [CI], 4-16; P = 0.003); and 9 versus 13 μm at 5 years (mean difference, 4 μm; 95% CI, -2 to 10; P = 0.22). Central retinal venular equivalent decreased by 14 versus 19 μm at 2 years (mean difference, 4 μm; 95% CI, -3 to 11; P = 0.26) and 18 versus 28 μm at 5 years (mean difference, 11 μm; 95% CI, 3-19; P = 0.01).

CONCLUSIONS

In patients with PDR, CRAE and CRVE decreased in both the ranibizumab and PRP groups at 5 years, but the rates of change before and after 2 years may be different. In this subset of eyes from Protocol S, the greater reduction in CRAE in the PRP group was statistically significant at 2 years but not at 5 years. For CRVE, the PRP group decreased more than the ranibizumab group, but the difference was statistically significant at 5 but not 2 years. Future research may investigate the underlying causes for retinal arteriolar and venular narrowing after treatment for PDR, and the possibility of an anatomic correlation with visual field loss.

FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.