Pachychoroid-Related Pigment Epithelial Detachment Treated with Photodynamic Therapy

Background: Pachychoroid pigment epitheliopathy (PPE) is a non-exudative entity within the pachychoroid disease spectrum characterized by increased choroidal thickness and isolated serous pigment epithelial detachment (PED) without subretinal fluid. Although photodynamic therapy (PDT) is established for chronic central serous chorioretinopathy (CSC), its efficacy in isolated pachychoroid-related PED remains insufficiently defined, with available evidence limited to small case series. Purpose: This study aims to characterize symptomatic pachychoroid-related PED and evaluate anatomical and functional outcomes following half-dose PDT (hd-PDT), with additional analysis according to lesion localization and CSC history. Methods: This retrospective study included 34 eyes of 27 patients treated with hd-PDT between June 2022 and December 2024. PEDs were categorized as central (fovea-involving) or paramacular. Best-corrected visual acuity (BCVA) and spectral-domain optical coherence tomography parameters-central subfield thickness (CST), mean subfield thickness (MST), macular volume (MV), subfoveal choroidal thickness (SFCT), and PED height-were assessed at baseline, 1 month, and 6 months. Treatment planning was based on indocyanine green angiography (ICGA) and spectral-domain optical coherence tomography (SD-OCT) findings. Statistical analyses employed non-parametric tests and generalized estimating equations. Results: Central lesions were associated with longer disease duration, worse baseline BCVA, and greater retinal thickness and PED height (p < 0.05). Complete PED resorption occurred in 79.4% of eyes at 1 month and 73.5% at 6 months (central: 86.3% and 81.8%; paramacular: 66.6% and 58.3%). Mean BCVA improved significantly from 0.22 ± 0.24 to 0.10 ± 0.16 logMAR at 6 months (p < 0.0001), with greater functional gain in central lesions. Significant reductions were observed in CST, MST, MV, and PED height, whereas SFCT remained stable. Better final BCVA correlated with younger age, shorter disease duration, smaller baseline retinal volume, smaller PDT spot size, and absence of CSC history. Non-responders had worse baseline BCVA, higher PED height, and larger treatment areas. No treatment-related complications were detected. Conclusions: Half-dose PDT was associated with favorable anatomical and functional outcomes in symptomatic pachychoroid-related PED, particularly in centrally located lesions. Baseline disease severity appeared to influence treatment response. Prospective studies with longer follow-up are warranted to confirm long-term efficacy and safety.