Purpose: The long-term clinical outcome of adjuvant stereotactic radiotherapy (SRT) in neovascular age-related macular degeneration (nAMD) patients was evaluated.
Methods: This case-control study included patients with unilateral nAMD, who underwent SRT complementary to standard anti-VEGF treatment. Only patients with monthly follow-up over at least three years were considered. Number of intravitreal injections, visual acuity (VA), central retinal thickness (CRT), and subfoveal choroidal thickness (SFCT) were evaluated and compared to baseline as well as to an age- and gender-matched control group, who received anti-VEGF monotherapy.
Results: Twenty patients were irradiated and had complete follow-up. Cumulatively, SRT patients needed significantly less injections than non-irradiated ones over three years (14 vs. 18, p = 0.014), while median VA did not show statistically significant changes (0.4 logMAR at baseline to 0.65 logMAR at final follow-up, p = 0.061). CRT remained steady, but SFCT showed a continuous thinning of almost 50 μm (p = 0.031) in irradiated patients over three years. Multiple linear regression analysis revealed that SFCT and VA at time of irradiation are significant prognostic factors of VA change in SRT patients over the following three years (F(2,17) = 23.946, p<0.001, R2 of 0.738).
Conclusions: SRT significantly reduced the cumulative anti-VEGF treatment burden over three years, however, this was mainly driven by the results of the first year after irradiation. A thinner SFCT at time of irradiation was associated with poorer visual outcome. While further research and investigation are warranted to elucidate the underlying pathogenesis, SFCT could be a potential biomarker when evaluating a patient's suitability for SRT.
Keywords: Neovascular AMD; Optical coherence tomography; Stereotactic radiotherapy; Subfoveal choroidal thickness.
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