In this review, we distinguish among risk factors associated with the development of open-angle glaucoma in individuals with healthy eyes, predictive determinants for the development of open-angle glaucoma in subjects with ocular hypertension, and prognostic factors for the progression of open-angle glaucoma in individuals who already have the disease. We primarily reviewed recent longitudinal population-based epidemiological studies, prospectively planned clinical trials, and cohort studies. Risk factors consistently associated with the development of open-angle glaucoma in individuals with healthy eyes include older age and an approximately 1 mm Hg increase in intraocular pressure (IOP) at baseline. Family history for open-angle glaucoma may be associated with the development of open-angle glaucoma as well. Predictive factors for the development of open-angle glaucoma in individuals with ocular hypertension may be older age, thinner central corneal thickness, higher cup-to-disk ratios of the optic disc, and higher pattern standard deviation values on the Humphrey automated perimeter at baseline. Given multi-center trials that showed similar predictive factors for the development of open-angle glaucoma in individuals with ocular hypertension, a calculator is available to clinicians for assessing the 5-year likelihood of developing open-angle glaucoma in ocular hypertensive patients with certain characteristics. Prognostic factors for the progression of open-angle glaucoma in individuals who already have the condition include older age at baseline, higher IOP at baseline, and thinner central conreal thickness. Self-report of diabetes may be associated with open-angle glaucoma progression. In conclusion, the only modifiable factor associated with open-angle glaucoma that has been consistently identified is elevated baseline IOP. Future research needs to evaluate the importance of others modifiable factors such as IOP fluctuation or nutritional factors.