Long-term effect of panretinal photocoagulation on optic nerve head parameters in diabetic retinopathy using Heidelberg retinal tomography III

PURPOSE: The aim of this study was to evaluate the effect of panretinal photocoagulation (PRP) in diabetic retinopathy patients using Heidelberg retinal tomography III (HRT). SUBJECTS AND METHODS: A total of 90 eyes of 90 consecutive newly diagnosed patients with diabetic retinopathy (nonproliferative diabetic retinopathy, NPDR, Group I and proliferative, PDR, Group II) were recruited for the study. The eyes with PDR were subjected to PRP. The effect of PRP was measured on optic nerve head (ONH) parameters using HRT. RESULTS: Follow-up up to 4 years in both groups indicated that in Group II proliferative diabetic retinopathy (PDR) participants undergoing PRP, the ONH parameters showed a significant difference in cup area (P = 0.023), cup volume (P = 0.001), mean cup depth (P = 0.015), maximum cup depth (P < 0.001), mean retinal nerve fiber layer (RNFL) thickness (P < 0.001) at 1 year of follow-up, and remained significant in all at 4 years of follow-up, whereas there was no significant difference in any of the optic disc parameters in the participants of Group I belonging to NPDR group as compared to PDR group after 4 years. CONCLUSION: PRP affected the ONH morphology in the PDR group and the effect of this change should be interpreted with caution. This may require setting a new baseline for RNFL measurements using the HRT when documenting RNFL loss or glaucoma progression in patients who have undergone PRP.