Microvascular abnormalities and long-term efficacy after stereotactic radiotherapy under continued intravitreal anti-VEGF treatment for neovascular AMD

Polypoidal Choroidal Vasculopathy after Stereotactic Radiotherapy for Neovascular Age-Related Macular Degeneration: A Case Report with Long-Term Follow-Up

Several adjunct therapies to the gold standard anti-vascular endothelial growth factor (anti-VEGF) intravitreal injections have been discussed for the treatment of neovascular age-related macular degeneration (nAMD). Low-dose stereotactic radiotherapy (SRT) showed the potential to lower the treatment burden by reducing the anti-VEGF treatment frequency at least over 2–3 years but was associated with retinal microvascular abnormalities in a few cases. We report a 6-year follow-up of a case with bilateral nAMD under anti-VEGF treatment which developed multiple polypoid choroidal vasculopathy (PCV) lesions in the eye adjunct treated with low-dose SRT. The fellow eye suffering from nAMD for the same period of time but never been treated with SRT did not show PCV during the long-term follow-up. We hope to increase the awareness of possible choroidal changes such as PCV in similar patients by sharing this report.

In vitro evaluation of simulated stereotactic radiotherapy for wet age-related macular degeneration on three different cell lines

Low energy stereotactic radiotherapy has been proposed for the treatment of neovascular age related macular degeneration. We investigated the in vitro effect of the radiotherapy on pericytes, retinal pigment epithelium and endothelial cells. Primary human retinal pigment epithelium cells, human umbilical vein endothelial cells and human pericytes from Placenta were cultivated. In a pairwise protocol, one plate was irradiated at a dose of 16 Gy, while the second plate served as a non-irradiated control. Thereafter, cells were cultivated either in serum-free (non-permissive) or serum-stimulated (permissive) conditions. A life/dead assay, an XTT and a BrdU assay were performed up to 7 days after irradiation. No cell death occurred at any timepoint in any cell line after treatment nor in the control. Compared to the unirradiated controls, cell viability and metabolic activity were significantly reduced in irradiated cells in the XTT assay, except for non-permissive RPE cells. In the BrdU assay, proliferation was inhibited. While no cell death was detected in vitro, viability and proliferative capacity of all cell lines were significantly reduced. Therefore, it seems that low energy stereotactic radiotherapy inhibits angiogenesis without a direct induction of apoptosis but influencing microvascular function and stability.