Incidence and Sequelae of Macular Edema Post Pan-retinal Photocoagulation for Proliferative Diabetic Retinopathy

Purpose To study the incidence and sequelae of macular edema after Panretinal photocoagulation (PRP) for the treatment of proliferative diabetic retinopathy (PDR). Patients and Methods A prospective interventional clinical study included 42 eyes treated by PRP, for proliferative diabetic retinopathy over three sessions on three consecutive weeks. Baseline and 1-month postoperative data were collected including best-corrected visual acuity, detailed fundus examination and Spectral Domain Optical Coherence Tomography Macula (SD-OCT); to assess the Central Subfield Macular Thickness (CSMT) using the ETDRS Map. Results Forty-two eyes of 31 patients were included in the study with mean duration of diabetes of 16.9±5.7 years and mean HbA1c of 9.1±1.4. Mean pre-PRP vision was 0.44±0.2 log units, which improved to 0.41±0.2 log units (P=0.6). Mean pre-laser CSMT was 245.6±25.5 µm, which increased to 265.5±33.5 µm at 1-month follow-up after PRP (P=0.003). Four eyes (9.5%) had CSMT more than 300 µm with intraretinal edema. The mean change and percentage of change from baseline in CSMT between those patients and remaining patient were statistically insignificant (P=0.055 and 0.115 respectively). Changes in CSMT and changes in Log MAR BCVA at 4-week follow-up were inversely correlated. Conclusion Macular edema can be an unavoidable side effect of PRP especially in cases with baseline increased macular thickness. Vision is mostly not affected by PRP, however, changes in vision may be directly affected by macular thickness post-PRP.