In open-angle glaucoma, the iridocorneal angle remains open, but the trabecular meshwork becomes stiff, slowing down the outflow of aqueous humor. This causes a buildup of aqueous humor in the anterior chamber, leading to a sudden increase in intraocular pressure. The treatment for open-angle glaucoma focuses on reducing the elevated intraocular pressure by either decreasing the secretion of aqueous humor or increasing its outflow.

Drugs such as carbonic anhydrase inhibitors, α₂- and β-adrenergic blockers (e.g., brinzolamide, brimonidine, and timolol) are used to reduce the secretion of aqueous humor. Conversely, drugs like rho kinase inhibitors, prostaglandins, and cholinomimetics (e.g., netarsudil, latanoprost, and pilocarpine) increase the outflow of aqueous humor. These medications are typically administered topically as eye drops.

Although these drugs effectively lower intraocular pressure, they can also have side effects. For instance, brinzolamide, brimonidine, and timolol may cause burning, sleepiness, and bronchoconstriction, respectively. Similarly, netarsudil, latanoprost, and pilocarpine can lead to blurriness, changes in iris pigmentation, and weakened vision, respectively.