[Chorioretinal anastomosis as unfavourable prognostic factor during photodynamic therapy]

The aim of this study was the documentation of chorioretinal anastomosis in neovascular age-related macular degeneration (AMD) and correlation with functional and angiographic results following photodynamic therapy (PDT).

A total of 100 patients presenting with neovascular AMD and indication for PDT based on the presence of predominantly classic choroidal neovascularization (CNV), underwent ophthalmoscopic and angiographic screening for chorioretinal anastomosis. Conventional PDT using verteporfin was performed according to the recommended standard procedure. The pre- and post-treatment status at 3 and 6 months post-PDT in all patients and at 1 week in selected patients was documented with respect to the central visual acuity test (ETDRS), ophthalmoscopy as well as fluorescein (FA) and indocyanine green angiography (ICGA).

A primary chorioretinal anastomosis was found in 6% ( n=12) of all eyes with CNV and classic PDT indication. Mean visual loss within the first 6 months after therapy was 3 lines indicating lack of visual stabilization according to the PDT study criteria.Furthermore, an increase in visual acuity could not be documented in any case. Angiography demonstrated continuous progression of CNV size although PDT had been uneventful. The characteristic initial occlusion of the CNV with homogeneous hypofluorescence was absent angiographically at 1 week post-PDT. The anastomosis was detected by ICGA in all eyes and by ophthalmoscopy or optical coherence tomography (OCT) in most eyes.

Chorioretinal anastomosis is not a rare finding associated with predominantly classic CNV. The presence of anastomosis appears to be an unfavourable prognostic factor during PDT. If a chorioretinal shunt is suspected evaluation by ICGA and/or OCT should be performed and the indication for PDT should be rediscussed.