Comparison of Retinochoroidal Vascular and Structural Changes after Half-Dose Photodynamic Therapy versus Half-Fluence Photodynamic Therapy Based on Optical Coherence Tomography Angiography in Eyes with Chronic Central Serous Chorioretinopathy

Abstract

Purpose: The aim of this study is to compare the efficacy of half-fluence photodynamic therapy (PDT) and half-dose PDT on the choroidal structure via perfusion of the retinal plexus and choriocapillaris in eyes with chronic central serous chorioretinopathy (cCSCR). Materials and Methods: This retrospective study included 43 eyes in 43 patients with cCSCR. Patients in group 1 received half-fluence (verteporfin 6 mg m⁻²) PDT and those in group 2 received half-dose (verteporfin 3 mg m⁻²) PDT. Enhanced depth imaging optical coherence tomography and optical coherence tomography angiography (OCTA) images were recorded 1 day before and 3 months after PDT. Total choroidal area (TCA), luminal area (LA), and stromal area (SA) were calculated using Image J software. Results: From baseline to 3 months post PDT TCA decreased from 2.43 ± 0.47 mm² to 2.08 ± 0.59 mm² (p < 0.001), LA decreased from 1.78 ± 0.11 mm² to 1.54 ± 0.26 mm² (p < 0.001), and SA decreased from 0.76 ± 0.33 mm² to 0.53 ± 0.37 mm² (p < 0.001) in group 1. Choriocapillaris vascular density measured via OCTA increased from 37.82 ± 10.99 at the initial visit to 44.96 ± 15.34 at month 3 after half-fluence PDT administered to the fovea (p < 0.001). Deep capillary plexus vessel density was 32.49 ± 11.36 at baseline and increased to 43.27 ± 11.40 at month 3 after half-fluence PDT administered to the fovea (p < 0.001) in group 1. TCA decreased to 2.00 mm² ± 0.51 mm² from 2.39 mm² ± 0.43 mm² (p < 0.001), LA decreased to 1.53 ± 0.29 mm² from 1.74 ± 0.16 mm² (p = 0.019). Although SA decreased from 0.76 ± 0.33 mm² to 0.53 ± 0.37 mm² in group 2, the difference was not significant (p = 0.07). Based on OCTA, choriocapillaris vascular density increased from 43.68 ± 10.38 mm² at baseline to 47.46 ± 6.42 mm² at 3 months after half-dose PDT onto the fovea (p = 0.049). Deep capillary plexus vessel density increased from 34.37 ± 9.36 mm² at the initial visit to 38.17 ± 8.81 mm² 3 months after half-dose PDT onto the fovea (p = 0.046) in group 2. At 3 months, post-PDT subretinal fluid (SRF) was significantly higher resolution in group 1 than in group 2 (p = 0.021). Conclusions: OCTA shows there is a significant increase in deep capillary plexus and choriocapillaris perfusion 3 months after both half-fluence PDT and half-dose PDT. Although there was a significant decrease in LA in both groups, based on OCTA there was a significant decrease in SA, a significant increase in choriocapillaris and deep capillary perfusion in group 1; therefore, the level of SRF resolution at month 3 post PDT might explain its higher incidence in group 1.