Microstructural changes after half-dose photodynamic therapy in patients with chronic central serous chorioretinopathy

Background: To evaluate the retinal and choroidal microstructural changes at fovea after half-dose photodynamic therapy (PDT) in patients with chronic central serous chorioretinopathy (CSC), using optical coherence tomography (OCT). Methods: The study included 35 eyes with unilateral chronic CSC treated with half-dose PDT. The foveal outer nuclear layer (ONL) and subfoveal choroidal thickness (SFCT) in the affected eyes were compared with baseline measurements at month 1, 3, and 6 after half-dose PDT, and those of the healthy contralateral eyes. Results: The mean baseline ONL thickness of the affected eyes was thinner compared to unaffected fellow eyes (66.9 +/- 16.5 mu m vs 111.5 +/- 11.6 mu m, p<0.001), and increased significantly to 68.6 +/- 17.0 mu m at month 3 and 68.9 +/- 17.3 mu m at month 6 after treatment (p = 0.025 and p = 0.014 respectively). The mean baseline SFCT of the affected eyes was thicker compared to unaffected fellow eyes (399.9 +/- 87.0 mu m vs 338.2 +/- 75.4 mu m, p<0.001), and decreased significantly after treatment at month 1, 3, and 6 (374.0 +/- 84.8 mu m, 369.7 +/- 81.8 mu m, 367.3 +/- 80.8 mu m respectively, p<0.001 for all). The responder group (n = 26), in which subretinal fluid was completely resorbed, showed a significant increase in ONL thickness and decrease in SFCT after treatment, whereas in the non-responder group (n = 9) ONL thickness and SFCT did not differ after treatment. Conclusions: In CSC patients, significant changes are observed in foveal ONL thickness and SFCT after half-dose PDT. ONL thickness and SFCT are suggested to be considered in the OCT examinations of CSC patients.