Prostaglandin Analogues

photographs depicting hyperemiaThis is the newest class of glaucoma drugs, which includes travoprost and latanoprost. Prostaglandin analogues were first introduced in 1996. They all work by increasing the flow of aqueous humor out of they eye, thus lowering IOP. Prostaglandin analogues are dosed once a day, preferably at bedtime and effectively control IOP for many years.

Prostaglandins can cause eyelash growth and occasionally can darken the lids. One of the more common side effects of prostaglandin analogues is hyperemia (also known as redness of the eye). If hyperemia occurs it is usually rated as mild, as shown in the pictures at left. In patients new to the prostaglandin analogues, the hyperemia may appear more pronounced, but it usually subsides to a mild level within a few weeks.

In a small number of patients, prostaglandin analogues may gradually darken eye colour by increasing the amount of brown colouring in the iris. Although these changes can occur slowly, they may be permanent.

Beta Blockers

These drugs have been around to treat glaucoma for decades. The most commonly used beta blocker is timolol. The dosing of beta blockers ranges from once to twice daily. Beta blockers work by decreasing production of aqueous humor, which lowers IOP. Some of the side effects include low blood pressure, slow heart rate, and general fatigue.

Alpha Agonists

Brimonidine is the most common alpha agonist. It should be dosed two times a day in the eye. Alpha agonists cause an increase in outflow, as well as a decrease in production, of aqueous humor to lower IOP. Side effects may include ocular allergic reactions, dry mouth and drowsiness.

Carbonic Anhydrase Inhibitors

Carbonic anhydrase inhibitors are available in oral formulations or eye drops like brinzolamide or dorzolamide. Dosing for these eye drops is three times a day. Carbonic anhydrase inhibitors lower IOP by decreasing production of aqueous humor. The severe side effects, such as nausea and diarrhea, common with the oral forms, are largely avoided with eye drops. The eye drops are fairly well tolerated, but may cause a minor ocular stinging or burning sensation.


Pilocarpine is the most common miotic. It has been around for decades and is usually dosed three to four times a day. Miotics decrease IOP by increasing outflow of aqueous humor. Side effects may include blurred vision, brow ache, and small pupil size.

Information on this page provided by Alcon Canada Inc.