Half-Fluence, Half-Dose Photodynamic Therapy: Less Direct Damage but More Inflammation?

Objective: To present clinical findings and multimodal imaging of three patients who developed bacillary layer detachments (BALADs) shortly after half-fluence, half-dose (HFHD) verteporfin photodynamic therapy (PDT). Methods: Retrospective observational case series. Three patients were treated with HFHD-PDT for (1) macular neovascularisation five years after resolved central serous chorioretinopathy (CSC), (2) persistent serous retinal detachment (SRD) from chronic CSC, and (3) neovascular age-related macular degeneration with persistent SRD despite intravitreal anti-VEGF therapy. Results: Each patient developed a BALAD after HFHD-PDT. Acute fulminant exudation caused subretinal fluid expansion into the inner photoreceptor layer, cleaving myoid from ellipsoid zones in the central macula. Subretinal fluid and the BALADs subsequently resolved over 6-8 weeks. Conclusions: The subretinal fluid and BALAD following HFHD-PDT were transient and did not cause photoreceptor damage over a 6-month follow-up period. We speculate that the reduced-impact HFHD protocol decreases direct tissue damage but increases proinflammatory cytokines. The long-term pathophysiological consequences of the resolved BALADs are unknown.