Birla S, Gupta D, Somarajan BI, et al. - Using cluster analysis, researchers classified unrelated patients with juvenile onset primary open angle glaucoma (JOAG) into clinically useful phenotypes. Of the 527 unrelated JOAG patients, 414 patients with all the phenotypic characteristics needed for the study were included. A cluster analysis was conducted to classify the individuals based on their iris and angle morphology, age of onset, highest untreated intraocular pressure (IOP), worst mean deviation and greatest vertical cup disc ratio of the worst eye. Identified four major clusters were: Cluster 1 with normal iris crypts (NIC) and normal angles had the lowest untreated IOP and higher age of onset among all clusters. Cluster 2 with NIC and featureless angle was found to be linked to the earliest age of onset. Cluster 3 had NIC and either elevated insertion of the iris or prominent iris processes. Cluster 4 was a heterogeneous cluster with a maximum number of patients in a group of PIC patients and high insertion of iris. Findings suggested that cluster analysis has extracted four JOAG phenotype subgroups that have clinical and prognostic significance and can be useful in assessing these patients in clinics.