Quantitative evaluation of damage to retinal capillaries caused by half-dose and half-time photodynamic therapy with optical coherent tomographic angiography

Abstract

Purpose: To determine and compare retinal capillaries damage in patients with chronic central serous chorioretinopathy (CSC) after half-dose and half-time photodynamic therapy (PDT) based on optical coherence tomographic angiography (OCTA). Methods: Thirty-three eyes of 33 patients and 32 eyes of 32 patients with active CSC were treated with half-dose PDT and half-time PDT respectively and followed up for 3 months. Fundus fluorescein angiography (FFA) and indocyanine green angiography (ICGA) were performed at baseline; best corrected visual acuity (BCVA) and OCTA were performed at baseline, 3-day, 7-day, 14-day, 1-month, and 3-month follow-up visits. Results: Twenty-eight patients in half-dose group and 27 patients in the half-time group finished the 3-month follow-up visits. BCVA was significantly improved at post-PDT 1 month and 3 months (both P < 0.05) and central macula thickness (CMT) was significantly decreased at all post-PDT time points (all P < 0.05) in both groups. 22 patients (78.57%) in the half-dose group and 21 patients (77.78%) in the half-time group had complete absorption of subretinal fluid (SRF) at post-PDT 3 months. There was no significant difference in the above-mentioned prognostic measurements between two groups. The mean vessel densities of superficial retina (VDSR) and inner retina (VDIR) layers were decreased at all post-PDT time points in both groups. However, the decrease of VDIR and VDSR at post-PDT 3 days and 3 months in the half-dose group was much severe than those in the half-time group (P < 0.05). Conclusions: Both half-dose and half-time modifications of PDT were similarly effective in improving the BCVA and decreasing the SRF for chronic CSC. However, the retinal capillaries damage in the half-time group was less severe than that in the half-dose group, so the half-time modification may be a more appropriate parameter for patients with chronic CSC.