Effects of Latanoprost, Bimatoprost and Travoprost in Patients With Latanoprost-resistant Glaucoma

Intraocular pressure (IOP) is considered to be the main risk factor for progression of glaucoma and therefore the main target of therapy. Pharmacologic treatment of glaucoma has changed considerably during the last decades due to the introduction of prostaglandin analogues. Three of these are commonly used in North America: latanoprost (Latanoprost T, Pfizer), Travoprost (Travatan TM, Alcon) and bimatoprost (Lumigan TM, Allergan).

There have been several studies to evaluate their effectiveness. The three seem to be equivalent, according to the only study that has compared the molecules. Latanoprost is employed initially, due to its paucity of side effects when compared to the other two analogues. However, if it is not effective, several studies ahve shown that a result is possible using either travoprost or bimatoprost. No study has been conducted to date systematically comparing the three molecules in cases of resistance to latanoprost. In actuality, the investigators patients will receive treatment identical to current practice with the exception of the group continuing with latanoprost. Several studies confirm the benefit of changing prostaglandin analogues if the first has not signficantly decreased the IOP (Palmberg et al. 2004). Each prostaglandin has unique properties which may cause the mechanism of action to vary slightly among patients. (cf. Pharmacological Aspects)

The goal of the study is thus to evaluate the efficaciousness of latanoprost, bimatoprost and travoprost in their IOP-lowering capacity in patients who do not initially respond to latanoprost.