Advances in topical glaucoma therapy

Significant advances have recently been achieved in the development of topical glaucoma medications. The primary advantage of a topical preparation is the reduced incidence of adverse systemic effects attributable to a given drug compared to its systemically administered counterpart. However, the strong protective barrier of the eye forces topical ophthalmic preparations to be highly concentrated and in some cases, they have the potential to produce unwanted systemic effects, particularly in smaller animals. Oral carbonic anhydrase inhibitors are commonly associated with adverse effects in both humans and animals. Two recently developed topical carbonic anhydrase inhibitors, dorzolamide and brinzolamide, have shown promise in reducing intraocular pressure in animals and systemic side effects are apparently limited with their use. The topical alpha(2)-agonist apraclonidine, on the other hand, effectively reduces intraocular pressure in cats and dogs, but in its currently available form is likely to induce unwanted systemic effects. Latanoprost is a topical prostaglandin F,,, analog that has proven effective in reducing intraocular pressure in dogs and horses, but while systemic side effects have not yet been reported, this topical preparation may exacerbate pre-existing or concurrent ocular inflammatory disease.