One-year follow-up of macular ganglion cell layer and peripapillary retinal nerve fibre layer thickness changes after panretinal photocoagulation

Background/aims To assess the changes of ganglion cell-inner plexiform layer (GCIPL) thickness, retinal nerve fibre layer (RNFL) thickness, and central subfield thickness (CST) after panretinal photocoagulation (PRP) in diabetic retinopathy for 1 year. Methods This prospective, interventional case series study examined 35 patients (35 eyes) undergoing PRP, who were diagnosed with severe non-proliferative diabetic retinopathy to non-high-risk proliferative diabetic retinopathy without macular oedema. Macular GCIPL thickness, CST, and peripapillary RNFL thickness were measured by spectral-domain optical coherence tomography at baseline, and then at 1, 3, 6, 9 and 12 months after PRP. Results Macular GCIPL and peripapillary RNFL (average and all sections) thickness at each follow-up increased significantly from the baseline (p≤0.001, respectively). The average, superior and inferior RNFL thickness at 12 months after PRP decreased significantly compared to the 1-month post-PRP (p=0.007, p=0.028 and p=0.025). The average GCIPL and temporal RNFL thickness showed a significant correlation at each followup (p≤0.001, respectively). CST at each follow-up increased significantly from the baseline ( p≤0.001, respectively). Conclusions The macular GCIPL and peripapillary RNFL thickness increased throughout the 1-year post- PRP. Furthermore, the macular GCIPL and temporal RNFL thickness showed a significant correlation throughout the 1 year of follow-up.