PURPOSE: Venous overload choroidopathy, showing pachyvessels, choroidal intervortex venous anastomoses, asymmetric venous drainage, choroidal vascular hyperpermeability (CVH), and increased choroidal thickness, is observed in most patients with central serous chorioretinopathy based on ultrawidefield indocyanine green angiography. This report investigates how photodynamic therapy alters signs of venous overload choroidopathy. METHODS: The CERTAIN study is a monocentric, retrospective study on consecutive central serous chorioretinopathy patients who underwent ultrawidefield indocyanine green angiography. For this report, patients who underwent ultrawidefield indocyanine green angiography twice were included. Two independent graders assessed changes in pachyvessels, choroidal intervortex venous anastomoses, AVD, choroidal thickness, and CVH when comparing pre-photodynamic and post-photodynamic therapy images of treated and untreated eyes. RESULTS: In total, 38 eyes (19 patients) were included. Of those, 19 eyes had undergone photodynamic therapy, and 19 had not. Photodynamic therapy had no significant effect on pachyvessels, choroidal intervortex venous anastomoses, and asymmetric venous drainage (all P >
0.05). Only choroidal thickness (-51 ± 48 vs. 1 ± 43 µ m, P = 0.006) and CVH within the photodynamic therapy treatment area (79% vs. 0% reduced CVH, P <
0.0002) were significantly decreased in treated versus untreated eyes. CONCLUSION: Photodynamic therapy reduced choroidal thickness and CVH within the treatment area while not significantly altering the overall choroidal vascular architecture associated with venous overload choroidopathy.