Purpose: To determine the association of statins, five classes of antihypertensive medications, and proton pump inhibitors with (1) primary open-angle glaucoma (POAG) progression and (2) conversion of POAG suspects to POAG. Methods: We retrospectively investigated the records of a cohort with POAG cases and suspects from the Groningen Longitudinal Glaucoma Study. To quantify visual field (VF) deterioration in cases, we used the rate of progression of the mean deviation (MD). Suspects were considered to have converted at the time point after which two consecutive VF tests for at least one eye were abnormal (glaucoma hemifield test outside normal limits). Progression and conversion were analyzed with quantile and logistic regression, respectively, with the systemic medications as predictors, controlling for age, sex, body mass index, pretreatment IOP, corneal thickness, and baseline MD. The multivariable models were built with and without IOP intervention. Results: No systemic medications were associated with POAG progression in the final IOP/treatment-adjusted or unadjusted model. However, angiotensin II receptor blockers (ARBs) appeared to slow progression in older patients (b = 0.014, P = 0.0001). Angiotensin-converting enzyme inhibitors (ACEIs) were significantly associated with a decrease in POAG suspect conversion in both the IOP/treatment-adjusted and -unadjusted model (odds ratio [OR] 0.23, 95% confidence interval [CI] 0.07-0.79, P = 0.012; OR=0.24, 95% CI 0.07-0.78, P = 0.021, respectively), as were ARBs (OR 0.12, 95% CI 0.01-0.98, P = 0.014; OR 0.11, 95% CI 0.01-0.87, P = 0.005, respectively). Conclusions: No overall association of VF progression with systemic medication was found; ARBs delayed progression in older patients. ACEIs and ARBs were associated with lower risk of suspect conversion. The pathophysiology of this relationship is to be disentangled.