Identification of type 1 retinopathy of prematurity (ROP) relies heavily on the presence of characteristics of plus disease, especially tortuosity. However, a relatively infrequent subset of eyes with type 1 ROP, eyes with zone 1, stage 3 ROP without plus disease, is included in treatment indications. We examined if posterior pole vessel width is associated with type 1 ROP in a subset of eyes with zone 1, stage 3 ROP without plus disease and whether vessel width differentiates type 1 from non-type 1 ROP.