One-year choroidal thickness changes after photodynamic therapy for central serous chorioretinopathy evaluated by widefield optical coherence tomography

Purpose To evaluate the changes in choroidal thickness 1 year after half-dose photodynamic therapy (PDT) for central serous chorioretinopathy (CSC) using widefield swept-source optical coherence tomography. Methods We retrospectively reviewed 21 patients with CSC who unilaterally underwent half-dose PDT and completed a 12-month follow-up. Choroidal thickness was evaluated before and after PDT within an 18-mm circular grid centered on the fovea subdivided into nine areas in the treated and untreated fellow eyes. Results All 21 treated eyes showed complete resolution of subretinal fluid at 3 months after PDT, without any recurrence at 12 months. The mean choroidal thickness in all nine areas significantly decreased after PDT at 3 months (P < 0.05) and remained unchanged at 12 months (P < 0.05) compared with that at baseline. However, the subtracted choroidal thickness maps between 3 and 12 months detected significant variations among the cases, classified into an enhanced pattern in 10 eyes (47.6%), an attenuated pattern in six eyes (28.6%), and a stable pattern in five eyes (23.8%). The 21 untreated fellow eyes also showed a decrease in mean choroidal thickness in three of the nine subdivided areas at 12 months (P < 0.05), but this decrease was limited posteriorly. Conclusion The reduction in mean choroidal thickness after half-dose PDT for CSC was extensively maintained for 1 year. However, subclinical hemodynamic changes in the entire choroid occurred longitudinally even in the absence of disease recurrence. Key Messages What is known: The reduction in mean choroidal thickness after half-dose photodynamic therapy (PDT) for central serous chorioretinopathy (CSC) was extensively maintained for 1 year. What is new: The decrease in widefield choroidal thickness was extensive 3 months after half-dose PDT for CSC and remained unchanged at 1 year. The difference in choroidal thickness maps between 3 and 12 months showed significant variations among the cases, indicating widely occurring subclinical changes in choroidal hemodynamics after PDT.