Using the MTAG POAG GWAS summary statistics and large-scale protein quantitative trait locus (pQTL) associations of European ancestry, we performed Mendelian randomization (MR) and identified 33 proteins that were potentially causally associated with risk of POAG (FDR adjusted P < 0.05; Supplementary Table 10), including the protein encoded by ENG that was also identified in the TWAS analysis based on retinal tissue. Here, ENG is linked to open-angle glaucoma.