ABSTRACT Glaucoma is a common cause of severe vision loss, characterized by the progressive loss of retinal ganglion cells. Several large genome-wide association studies (GWAS) for primary open angle glaucoma (POAG) have been performed to date and have discovered over 127 risk factor genes. The mechanism by which these genes lead to POAG is almost completely unknown. Our proposal seeks to 1) translate these risk factor gene discoveries into useful data for patients and their doctors and 2) determine the mechanisms by which risk factor genes confer risk. This proposal will leverage the results of prior GWAS studies along with the unmatched, 20-years of prospective clinical data from the Ocular Hypertension Treatment Study (OHTS) to develop a POAG risk calculator that includes both clinical and genetic risk factors that will be useful to patients and doctors (AIM1A). We will also conduct association studies of the OHTS cohort to identify genetic risk factors for rapid progression of POAG as measured by visual field parameters, with validation in a local Iowa cohort (AIM1B). Identifying genes associated with progression of glaucoma has great potential to personalize and guide glaucoma management. We will also investigate the functional consequences of specific glaucoma risk alleles with a range of complementary technologies. AIM2A will test the effects of risk alleles on gene expression and pathways with studies of genotyped human donor eyes using single-cell RNA sequencing (scRNAseq). Immunohistochemistry and ELISA of genotyped human donor eyes will also be used to determine the effects of risk alleles on the abundance and localization of the proteins they encode. Finally, in AIM2B will use BiT- STARR-seq to locate the specific variants (SNPs) in glaucoma loci that confer risk for glaucoma. These studies will begin to define the precise molecular steps that connect the presence of specific genetic risk factors in one’s genome to the development of glaucoma. Our proposal will lead to improved tools for ascertainment of a patient’s risk for POAG or risk for rapid worsening of POAG that can be readily transferred to clinicians in the form of better diagnostic and prognostic tools. Our proposal will also define the specific mechanisms by which risk factor alleles alter gene expression in key tissues (retinal ganglion cells), which will identify disease mechanisms and new therapeutic targets to facilitate development of targeted treatments. Our proposal has great potential to improve glaucoma care and reduce vision loss.