cited By 0; International audience; Purpose: To evaluate the use of the Lens Opacities Classification System III grading (LOCS III) for the characterization of radiation-induced cataract, and to correlate the proton beam projection onto the lens with cataract location and grade as defined by the LOCS III. Design: Prospective, interventional case series. Methods: Fifty-two consecutive patients with cataract following proton therapy were included. All cataracts were graded using LOCS III. Relationships between proton beam and cataract subtypes, as well as between dose, proportion of lens irradiated, and extent of cataracts, were assessed. Results: Tumor diameter, volume, stage, and equatorial tumor location were associated with extent of posterior subcapsular cataracts (PSC) that were diagnosed at a median (interquartile range) 36 months (22;83) after treatment. In multivariate analysis, the tumor volume (P