Kimiko Shimizu, Yohei Hashimoto, Keiko Azuma, Yoko Nomura, Ryo Obata, Hidenori Takahashi, Yasuo Yanagi

To evaluate the morphological changes in retinal microstructures following modified photodynamic therapy (PDT) for chronic central serous chorioretinopathy. Retrospective study of 21 consecutive eyes (age, 59±8.0 years [mean ± SD]) of 21 patients with chronic central serous chorioretinopathy. Inner foveal thickness (the distance between the internal limiting membrane and external limiting membrane), photoreceptor outer segment (PROS) length at the point without serous retinal detachment and choroidal thickness were assessed with enhanced depth imaging optical coherence tomography before treatment and at 1, 3 and 6 months after modified PDT. Six eyes had half-dose and 15 eyes had half-fluence PDT. PROS length within the irradiated area was significantly decreased by 3.9% at 1 month compared with that before modified PDT (43.5±5.72 and 40.5±7.53, P=0.020 [paired t-test]) and returned to baseline length at 3 and 6 months (43.0±5.42 and 43.5±4.33 μm [mean ± SD]; P=0.53 and 1.00 [paired t-test]). PROS length of the nonirradiated area at 1, 3 and 6 months after modified PDT did not significantly differ from that before PDT (41.8±6.35, 41.4±5.33, 41.9±4.67 and 42.3±4.26 μm [mean ± SD]; P=0.66, 0.90 and 0.60, respectively [paired t-test]). There was no significant change in inner foveal thickness during the observation period. At all time points, choroidal thickness was significantly thinner than it was before PDT (P<0.001, paired t-test). Modified PDT may cause mild temporary microstructural changes.