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 follow-up (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.