Comparing Half-Dose Photodynamic Therapy with Subthreshold Micropulse Laser for the Treatment of Central Serous Chorioretinopathy

Abstract

To compare the anatomical and functional outcomes of half-dose photodynamic therapy (PDT) and yellow 577 nm subthreshold micropulse laser (SMLT) in treating patients with chronic central serous chorioretinopathy (CSCR). Prospective, double-masked, randomized controlled clinical trial. Patients with chronic CSCR confirmed by clinical features and multimodal imaging. Eligible patients were randomized (1:1) to receive half-dose PDT or SMLT. The same treatment was repeated if persistent subretinal fluid (SRF) was observed. Treatment responses were evaluated 1 month after treatment and every 3 months until the endpoint at 12 months. The primary outcome measure was the complete resolution of subretinal fluid on optical coherence tomography (OCT) scan at month 12. Secondary outcomes included the changes in best-corrected visual acuity (BCVA), central macular thickness (CMT) as measured by OCT, retinal sensitivity as measured by microperimetry, and vision-related quality of life using the National Eye Institute 25-Item Visual Function Questionnaire. Between April 2017 and October 2020, 68 patients were recruited. At one month after treatment, SRF resolved in 8/33 (24.2%) patients receiving SMLT and 20/34 (58.8%) patients receiving half-dose PDT. This increased to 23/28 (82.1%) in the SMLT group and 30/33 (90.9%) in the half-dose PDT group at 12 months of follow-up. Kaplan-Meier survival curves showed significantly faster resolution of SRF in the half-dose PDT group than SMLT group (p=0.016). Both groups showed significant improvement in BCVA (-0.12 ± 0.21, p=0.005 for SMLT; -0.13 ± 0.12, p<0.001 for half-dose PDT), CMT (-154.2 ± 105.6, p<0.001 for SMLT; -140.8 ± 94.0, p<0.001 for half-dose PDT), and retinal sensitivity (5.70 ± 5.02, p<0.001 for SMLT; 6.05 ± 3.83, p<0.001 for half-dose PDT) at 12 months compared with baseline. There was no significant difference between the two treatment groups at each time point in all investigations except BCVA at 3 months (p=0.03). When comparing half-dose PDT to subthreshold SMLT this study has shown both treatments to be viable options, with half-dose PDT achieving faster anatomical success and functional improvement.