Glaucoma is a group of diseases that cause optic nerve damage and can lead to vision loss or blindness. Glaucoma is usually associated with elevated levels of pressure in the eye (called intraocular pressure, or IOP) that occur when the balance of fluids that are produced by and drained from the eye is not maintained. Several types of medications are used to treat glaucoma.
Beta Blockers
According to the University of Maryland Medical Center (UMMC), beta blockers are the drugs most commonly prescribed to treat glaucoma. They work to lower eye pressure by decreasing production of intraocular fluid (also called aqueous humor). Nonselective beta blockers affect all types of beta receptors throughout the body. Although that makes them effective at lowering IOP, it also means they may cause a number of side effects, including impaired heart function and breathing. Nonselective beta blockers include levobunolol HCI ophthalmic solution, timolol hemihydrate, carteolol, metipranolol, timolol maleate, timolol maleate ophthalmic solution and timolol maleate ophthalmic gel forming solution. Selective beta1 adrenoceptor beta blockers, including betaxolol HCI and levobetaxolol, bind to only one type of beta receptor in the body. They effectively reduce IOP and have fewer side effects on the heart than nonspecific beta blockers.
Alpha 2-Adrenergic Agonists
Alpha 2-adrenergic agonists are drugs that increase drainage of aqueous humor and decrease production of fluid in the eye. Alpha 2-adrenergic agonists available for glaucoma treatment include apraclonidine HCI and brimonidine tartrate. Brimonidine tartrate may be particularly effective for long-term treatment, and may be safer for use in those who are pregnant and those with asthma, according to UMMC.
Prostaglandin Analogs
Prostaglandin analogs are hormone-like substances that help promote drainage of intraocular fluid. Prostaglandin medications include unoprostone, latanoprost, travaprost and bimatoprost. According to the Glaucoma Research Foundation, 5 to 15 percent of people who use these medications will experience a gradual change in eye color.
Miotic Medications (Cholinergic Agonists)
Miotics, or cholinergic agonists, cause the iris to narrow and pupils to dilate which promotes drainage of aqueous humor and lowers IOP. Miotic medications used to treat glaucoma include pilocarpine HCI, pilocarpine HCI gel, pilocarpine HCI ophthalmic solution and carbachol.
Carbonic Anhydrase Inhibitors
Carbonic Anhydrase Inhibitors (CAIs) help to treat glaucoma by decreasing the production of aqueous humor in the eye, thus lowering IOP. CAI eye drops include brinzolamide ophthalmic suspension and dorzolamide HCI. Oral forms of CAIs include acetazolamide, methazolamide and dichlorphenamide. While oral CAI medications are more effective, they cause more side effects and are not typically used for long-term treatment. According to UMMC, CAIs are usually used when other glaucoma medications have failed.
Combination Medications
Combination medications are convenient for patients who would otherwise have to take multiple medications each day. Combination medications include brimonidine tartrate and timolol maleate (combination beta blocker and alpha agonist) and dorzolomide HCI and timolol maleate (combination beta blocker and carbonic anhydrase inhibitor).
