Pharmacological therapy for glaucoma - A review

For some time the medical treatment of glaucoma has consisted of topical be ta-blockers, adrenergic agents, miotics and oral carbonic anhydrase inhibit ors (CAIs). However, the therapeutic arsenal available for the medical trea tment of glaucoma has recently extended with new classes of ocular hypotens ive agents i.e. prostaglandins, local CAIs and alpha(2)-adrenergic agents. beta-Blockers are still the mainstay in glaucoma treatment and are first li ne drugs. However, even if they are applied once daily, as with timolol in gel forming solution and levobunolol, the possible cardiopulmonary adverse effects of beta-blockers remain a cause for concern. When monotherapy with beta-blockers is ineffective in reducing intraocular pressure (IOP) or is hampered by adverse affects, a change of monotherapy t o prostaglandins, local CAIs, alpha(2)-adrenergic agonists (brimonidine) or to dipivalyl epinephrine is advised. Prostaglandins, local CAIs and alpha(2)-adrenergic agonists, such as brimon idine, may in time become first line drugs because they reduce IOP effectiv ely and until now systemic adverse effects have rarely been reported with t hese agents. The development of a pro-drug of either a local CAI or an alph a(2)-adrenergic agonist with a sustained and continuous effect on IOP lever , which could be applied once a day is suggested. Because of these new developments, miotics, i.e, pilocarpine and carbachol, are recommended as second or third line drugs. The cholinesterase inhibito rs are considered third line drugs as better agents with fewer local and sy stemic adverse effects have become available. Oral CAIs may be used temporarily in patients with elevated IOPs e.g, posts urgery or post-laser, or continuously in patients with glaucoma resistant t o other treatment. Combining ocular hypotensive drugs is indicated when the target pressure fo r an individual patient cannot be reached with monotherapy. Combination the rapy of beta-blockers is additive with prostaglandins, topical CAIs and mio tics. Prostaglandins such as latanoprost can be combined with beta-blockers , adrenergic agents, local CAIs and miotics. Combinations with brimonidine or local CAIs need further investigation. Treatment of glaucoma with the new ocular hypotensive agents, either in mon otherapy or combination therapy, may provide lower IOPs and delay or postpo ne the need for surgery.