Initiating Proton Ocular Behandelings on General-Purpose Beamlines: Challenges and Trends From the Survey of US Facilities

Historically, ocular melanomas and other eye cancers accounted for a substantial share of proton therapy patients. Although the number of proton facilities in the United States increased rapidly in the last decade, as of 2025, only roughly 1 out of 6 had active ocular proton therapy (OPT) programs. Despite the robust growth in the number of proton treatments overall, eye treatments appear to have peaked in 2016. We aimed to identify barriers to the expansion of the availability of hypofractionated proton therapy for ocular cancer patients.