Octa evaluation of macular and optic disc vascular changes after PRP

This study aimed to evaluate the impact of panretinal photocoagulation (PRP) on macular and optic nerve head microvascular parameters using optical coherence tomography angiography (OCTA) in eyes with proliferative diabetic retinopathy (PDR) and very severe non-proliferative diabetic retinopathy (NPDR). In this prospective study, 56 treatment-naive eyes diagnosed with PDR or very severe NPDR and without diabetic macular edema were enrolled. PRP was performed over two sessions using a pattern scan laser in multispot mode. For each eye, the total laser ablation area (LAA) was calculated. OCTA imaging was performed before PRP, after the first PRP session, and at the 1-month follow-up. The following parameters were assessed: central macular thickness (CMT), subfoveal choroidal thickness (SFCT), foveal avascular zone (FAZ), superficial capillary plexus (SCP) vascular density (VD), deep capillary plexus (DCP) VD, and radial peripapillary capillary plexus (RPCP) VD. Twenty-seven eyes had very severe NPDR and 29 had PDR. One month after PRP, CMT increased significantly, while SFCT and best-corrected visual acuity remained unchanged. SCP-VD values (whole image, superior/inferior hemi-fields, parafoveal and perifoveal regions) were significantly reduced both 30 min and 1 month after PRP. DCP-VD values were significantly reduced at 30 min in all regions but returned to baseline by month one. FAZ area and perimeter did not change significantly, whereas foveal density-300 (FD-300) decreased both at 30 min and at one month. Regarding optic nerve head parameters, RPCP-VD inside the disc decreased at 30 min, and peripapillary RPCP-VD decreased significantly at the one-month visit. No correlation was found between LAA and changes in any OCTA parameter or OCT metrics. OCTA revealed that PRP induces measurable microvascular alterations in both the macula and optic nerve head. These findings suggest that PRP has acute and subacute effects on retinal and peripapillary microvasculature independent of total laser ablation area. What is known. • Panretinal photocoagulation (PRP) is the standard treatment for proliferative diabetic retinopathy (PDR) and may alter retinal vascular structure. • Optical coherence tomography angiography (OCTA) is a non-invasive imaging modality that enables quantitative evaluation of retinal and optic disc microvasculature. What is new. • This study quantitatively assessed early and one-month vascular changes in the macula and optic disc following PRP using OCTA. • Significant reductions in vessel density were observed early after PRP in both superficial (SCP) and deep (DCP) capillary plexuses; while DCP values returned to baseline by one month, some SCP parameters remained reduced. • Peripapillary vessel density (RPCP) showed significant early and sustained decreases in arterio-venous analysis post-PRP, but these changes were not correlated with the total laser application area.