Glaucoma - Treatment

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Adrenergic Agonists

Adrenergic agonists activate muscles in the eye that dilate pupils and, therefore, increase outflow of aqueous fluid. Newer variations called alpha 2-adrenergic agonists reduce production of aqueous humor and also increase outflow through the uveoscleral pathway (the alternative channel to the trabecular meshwork).

Brands. Apraclonidine (Iopidine) and brimonidine (Alphagan) are the alpha 2-adrenergic agonists used for glaucoma treatment. They are generally used before glaucoma surgery, but may be useful as primary therapy when used in combination with beta-blockers or other standard drugs.

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Side Effects. The most common side effects of brimonidine and apraclonidine are dry mouth and altered taste. They may also trigger an allergic reaction that causes red and itching eyes and lids. Brimonidine causes less of an allergic response than apraclonidine. Unlike apraclonidine, however, it can cause lethargy and mild low blood pressure.

Miotics (Pilocarpine and Others)

Miotics, also called cholinergic agonists, narrow the iris muscles and constrict the pupil. This action pulls the iris away from the trabecular meshwork and allows the aqueous humor to flow out through the drainage channels, reducing the pressure inside the front of the eye.

Brands. Pilocarpine (Pilocar, Adsorbocarpine, Almocarpine, Isoptocarpine, Ocusert) was the most widely used anti-glaucoma drug before timolol was introduced. It is the preferred miotic. Because pilocarpine is used up by the body fairly quickly, however, patients must take it several times a day; many people, therefore, fail to take this medication regularly. Carbachol (Isopto) is another miotic.

Epinephrine and its derivatives are the older anticholinergics. Epinephrine is now rarely prescribed because of side effects. Dipivefrin (Dipivefrin), a newer form of epinephrine, is effective in low doses and causes few systemic side effects.

Side Effects. Side effects may include:

• Teary eyes, brow-aches, eye pain, and allergic reactions.
• A miotic narrows the pupil and so can cause nearsightedness. Vision can also become dim and it may difficult to see in darkened rooms or at night, when driving could be hazardous.
• Miotics increase the risk of cataract development and are therefore used mostly in patients in whom cataracts have already been removed. Retinal detachment is an uncommon but dangerous side effect in susceptible individuals.
• Epinephrine can produce burning in the eyes, enlarged pupils, and allergic reactions. It sometimes causes anxiety and headaches. Rare side effects include high blood pressure and disturbances in heart rhythm. It is rarely prescribed now. Although dipivefrin, the newer form of epinephrine, has fewer systemic side effects, it still causes problems in the eyes similar to those of epinephrine.