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6.19:

Open Angle Glaucoma: Treatment

JoVE Core
Pharmacology
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JoVE Core Pharmacology
Open Angle Glaucoma: Treatment

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Recall that in open-angle glaucoma, the stiff trabecular meshwork impedes the aqueous humor outflow, increasing intraocular pressure. It is treated by reducing aqueous humor secretion or improving aqueous humor outflow to lower the intraocular pressure. To decrease humor secretion, drugs acting on adrenergic receptors of the ciliary body  are commonly used. For instance, brimonidine binds to α2-adrenergic receptors. While timolol binds to both β1 and β2 receptors on the ciliary epithelium. In addition, carbonic anhydrase inhibitors, such as brinzolamide, are also used to decrease aqueous humor secretion. Alternatively, to increase aqueous humor outflow, cholinomimetic drugs, such as pilocarpine, bind to muscarinic receptors and stimulate ciliary muscle contraction, thereby lowering intraocular pressure. Similarly, rho kinase inhibitors and prostaglandins also enhance the outflow and lower intraocular pressure. These drugs are administered topically as eye drops. However, they may exert several side effects. For example, brimonidine can cause sleepiness, timolol may lead to bronchoconstriction, and pilocarpine may weaken vision.

6.19:

Open Angle Glaucoma: Treatment

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.