Glaucoma is a group of eye disorders characterized by progressive deterioration of the optic nerve that can lead to vision loss. Primary open-angle glaucoma (POAG) is the most common form in the United States. The risk of POAG increases with age, family history of glaucoma, type 2 diabetes mellitus, hypotension, hypothyroidism, obstructive sleep apnea, cardiovascular disease, and myopia. Up to one-half of patients are undiagnosed because a diagnosis often requires monitoring over years to document changes suggesting POAG. These include a cup-to-disc ratio of 0.3 or greater, intraocular pressure greater than 21 mm Hg on tonometry, nerve fiber layer defects identified on optical coherence tomography, and reproducible visual field defects. Topical intraocular pressure–lowering medications and selective laser trabeculoplasty are first-line treatments for POAG. Although POAG screening in the general adult population is not recommended, primary care physicians can help decrease POAG-related vision loss by identifying patients with risk factors and referring them for evaluation by an eye specialist. Medicare covers evaluations in patients at high risk. Primary care physicians should encourage medication adherence and identify barriers to treatment. The other type of glaucoma is angle-closure glaucoma, in which the flow of aqueous humor is obstructed. Angle-closure glaucoma can occur acutely with pupillary dilation and is an ophthalmologic emergency. The goal of treatment for acute angle-closure glaucoma is to reduce intraocular pressure quickly with medications or surgery, then prevent the recurrence of the obstruction to aqueous flow by a definitive ophthalmologic procedure.