Transient accumulation of subretinal fluid after half-fluence photodynamic therapy in neovascular age-related macular degeneration

Background Photodynamic therapy (PDT) is known to occlude choroidal neovascularisation selectively, and there have been several reports on its adverse effects on the normal choroid and retinal pigment epithelium, resulting in decreased vision. Methods This retrospective interventional case series aimed to investigate the changes in visual acuity and retinal thickness in the immediate post-treatment period after half-fluence PDT, administered alone or with anti-vascular endothelial growth factor and steroids, in 29 eyes (26 patients) with neovascular age-related macular degeneration. The patients' best-corrected visual acuity (BCVA) and central foveal thickness (CFT) on optical coherence tomography images were measured 1 day, 1 week, and 1 month post-treatment. Results Compared to the pre-treatment CFT (270.38 mu m), the mean CFT was significantly increased 1 day post-treatment (387.07 mu m, P = 0.001), which then started to decrease, with a mean CFT of 269.32 mu m (P = 0.516) at 1 week, and of 240.66 mu m (P = 0.066) at 1 month post-treatment. All CFT increases were due to the accumulation of subretinal fluid (SRF), rather than the intraretinal or subretinal pigment epithelium fluid. Relative to the pre-treatment BCVA (0.59 logMAR), the mean BCVA at 1 day (0.74 logMAR, P = 0.005) and 1 week (0.75 logMAR, P = 0.002) post-treatment was significantly deteriorated; however, it recovered to 0.62 logMAR at 1 month. The patterns of change in CFT and BCVA did not differ according to treatment modality. Conclusions Half-fluence PDT resulted in accumulation of SRF in the immediate post-treatment period; this damage mostly recovered within a week, and the BCVA was restored within a month.