Panretinal Photocoagulation Versus Ranibizumab for Proliferative Diabetic Retinopathy: Factors Associated with Vision and Edema Outcomes

Purpose: To identify baseline factors associated with change in visual acuity or development of vision-impairing central-involved diabetic macular edema (DME) over 2 years when treating proliferative diabetic retinopathy (PDR) with ranibizumab or panretinal photocoagulation (PRP). Design: Post hoc analyses of randomized, multicenter clinical trial data. Participants: Eyes completing the 2-year visit (n = 328) or without vision-impairing central-involved DME at baseline (n = 302) in Diabetic Retinopathy Clinical Research Network Protocol S. Methods: Intravitreous ranibizumab (0.5 mg/0.05 ml) or PRP. Main Outcome Measures: Change in visual acuity (area under the curve) and development of vision-impairing (20/32 or worse) central-involved DME over 2 years. Results: After multivariable model selection with adjustment for baseline visual acuity and central subfield thickness, no factors were identified as associated with change in visual acuity or development of vision-impairing central-involved DME within the ranibizumab group. In the PRP group, worse change in visual acuity was more likely with higher hemoglobin A_1c level (–0.6 letters per 1% increase; 95% confidence interval [CI], –1.2 to –0.1 letters; continuous P = 0.03), more severe diabetic retinopathy (difference between high-risk PDR or worse vs. moderate PDR or better, –2.8 letters [95% CI, –5.5 to –0.2 letters]; continuous P = 0.003), and higher mean arterial pressure (difference between ≥100 mmHg vs. <100 mmHg, –2.0 letters [95% CI, –4.6 to 0.5 letters]; continuous P = 0.009). Development of vision-impairing central-involved DME was more likely with higher hemoglobin A_1c level (hazard ratio [HR] per 1% increase, 1.31 [95% CI, 1.13–1.52]; continuous P < 0.001), more severe diabetic retinopathy (HR for high-risk PDR or worse vs. moderate PDR or better, 1.46 [95% CI, 0.73–2.92]; continuous P = 0.03), and the presence of cystoid abnormalities within 500 μm of the macula center (HR, 2.90 [95% CI, 1.35–6.24]; P = 0.006). Conclusions: For eyes managed with PRP, higher hemoglobin A_1c level and more severe diabetic retinopathy were associated with less vision improvement and an increased risk of vision-impairing central-involved DME developing. When managing PDR with ranibizumab, eyes gained vision, on average, with no baseline characteristics identified as associated with visual acuity or central-involved DME outcomes.