Changes in choroidal vascular parameters following pan-retinal photocoagulation using swept-source optical coherence tomography.

Background: To assess the effect of pan-retinal photocoagulation (PRP) on choroidal vascular parameters in eyes with advanced diabetic retinopathy (DR).

Methods: Forty patients (65 eyes) with severe nonproliferative DR or proliferative DR who underwent PRP were included. Changes in choroidal vascular parameters were assessed at 3, 6, and 12 months after PRP by using swept-source optical coherence tomography (OCT) and OCT angiography and were compared with baseline values.

Results: Choroidal vascularity index (CVI) significantly decreased from 66.27% ± 1.55% at baseline to 65.85% ± 1.61%, 65.77% ± 1.29%, and 65.74% ± 1.60% at 3, 6, and 12 months after PRP, respectively. The ratio of luminal area to stromal area (L/S ratio) also significantly decreased from 1.98 ± 0.15 at baseline to 1.94 ± 0.14, 1.95 ± 0.13, and 1.93 ± 0.14 at 3, 6, and 12 months after PRP, respectively. The subfoveal choroidal thickness (SFCT) similarly showed a significant decrease from 319.50 ± 56.64 μm at baseline to 299. 07 ± 51.14 μm, 294.70 ± 58.96 μm, and 280.93 ± 53.57 μm at 3, 6, and 12 months after PRP, respectively. However, the choriocapillaris vessel density in both the fovea and parafovea showed no significant differences following PRP.

Conclusion: Eyes with advanced DR showed a significant reduction in CVI, L/S ratio, and SFCT over 12 months after PRP treatment.