Abstract
Purpose :
Though considerable work has been performed studying the retinal microvasculature in patients with uveal melanoma (UM) after plaque brachytherapy, the effects of proton beam therapy (PBT) on this microvasculature are not as well understood. We performed a cross-sectional study of patients with uveal melanoma who underwent proton beam therapy in order to assess retinal vascular changes at the macula and the peripapillary region using optical coherence tomography angiography (OCTA).
Methods :
We analyzed OCTA data from 17 adult patients with UM treated with PBT more than one year ago who returned for follow-up. OCT and OCTA data from the treated eye, including parafoveal capillary density from both superficial and deep plexuses, radial peripapillary capillary (RPC) density, and choriocapillaris flow ratio, were compared to the fellow untreated eye using Student’s t-test.
This study was approved by the University of California, Davis Institutional Review Board.
Results :
Several OCTA features demonstrated statistically significant differences between the two study groups. Peripapillary retinal nerve fiber layer (RNFL) thickness was decreased in the treated eyes as compared to the fellow eyes (88µm vs 102µm, p = 0.01). RPC density was also decreased in the same manner (42% vs 49%, p = 0.02). As previously described, the foveal avascular zone (FAZ) perimeter was increased in treated eyes.
Conclusions :
The microvasculature of the macula and notably radial peripapillary capillary density are negatively impacted in eyes which have undergone PBT for UM, even in eyes without clinical signs of radiation maculopathy or papillopathy. This is consistent with existing data showing similar changes with plaque brachytherapy. The susceptibility of this plexus to radiation damage is not fully understood but may be further elucidated with additional study of larger patient populations.
This is a 2021 ARVO Annual Meeting abstract.