[Effect of low-dose PDT on perfusion of the choriocapillaris in cCSCR : An OCT-angiography-based study]

In patients with chronic central serous chorioretinopathy (cCSCR) it is assumed that low-dose photodynamic therapy (PDT) induces short-term hypoperfusion of the choriocapillaris, which leads to long-term choroidal vascular remodeling and subsequent reduction of vascular hyperpermeability and leakage; however, it remains unclear whether the hypoperfusion completely returns to normal. The main aim of the retrospective study was to analyze the choroidal flow signal after treatment with low-dose PDT by optical coherence tomography-angiography (OCT‑A).

In this study 16 eyes with a total of 19 treated areas were included. Aside from visual acuity and metamorphopsia checks, all patients underwent enhanced depth imaging-OCT (EDI-OCT) and OCT‑A in the areas treated with low-dose PDT. In the present study, the flow signal in the choriocapillaris and choroidal thickness were measured retrospectively both in the PDT-treated area and in a non-treated reference area located in close proximity with similar eccentricity to the center of the fovea.

The study found a mean reduction of 33% (p < 0.001) of the choroidal flow signal in the treated area compared to the reference area and an average decrease in choroidal thickness of 71 µm (p = 0.001). In the long term 7 out of 10 patients suffered from metamorphopsia despite the low-dose PDT; however, visual acuity was improved in almost half of the patients by the treatment.

Using OCT‑A it could be shown that at the choriocapillaris level, hypoperfusion persists in spite of low-dose PDT. Thus, the choroidal vascular remodeling is not able to completely compensate for the hypoperfusion induced by thrombosis.