Use of apraclonidine in the treatment of acute angle closure glaucoma

A comparative study of Ocusert Pilo 40, intensive pilocarpine and low-dose pilocarpine in the initial treatment of primary acute angle-closure glaucoma

Acetazolamide and pilocarpine have a central role in the initial management of primary acute angle closure glaucoma (PACG), but there is no consensus concerning their mode of delivery, as borne out by a recent survey of senior UK ophthalmologists reported below. Ocusert Pilo 40 was developed to remain in situ releasing pilocarpine for up to one week. In view of its potential advantages, a trial of Ocusert Pilo 40's efficacy in PACG was conducted. In two separate controlled studies, eyes diagnosed with PACG were randomised to receive Ocusert Pilo 40, and either an intensive pilocarpine regimen or a low-dose pilocarpine treatment. All patients also received Diamox 500 mg i.v. Two hours after starting topical treatment, the study was terminated and ocular and systemic response to treatment and the eventual outcome were assessed. In both studies, intravenous Diamox caused a fall of intraocular pressure (IOP) within 30 min. Over the treatment period, a comparable reduction in IOP was seen in the Ocusert-treated, the intensive-pilocarpine-treated, and the low-dose-pilocarpine-treated groups. No damage to the corneas were observed.

Pharmacological advances in the treatment of glaucoma

Glaucoma is a potentially blinding disease. The goal of glaucoma therapy is to reduce intraocular pressure to a predetermined target level. There are currently 5 classes of compounds used for the medical management of glaucoma. Four classes that appear promising for the long term management of glaucoma are in different phases of clinical investigation, and include the topically active carbonic anhydrase inhibitors, selective alpha 2-adrenergic agonists, prostaglandins and ethacrynic acid. The topically active carbonic anhydrase inhibitor dorzolamide (MK-507) is effective and well tolerated in clinical trials of up to 1 year's duration. Animal studies have demonstrated that this drug lowers intraocular pressure by reducing aqueous humour formation. The selective alpha 2-adrenergic agonists, brimonidine and apraclonidine, have been shown to be effective in reducing intraocular pressure in the short term. Long term effectiveness of these agents is under investigation. Prostaglandins (PG) of the PGF2-alpha isopropylester series caused marked reductions of intraocular pressure in laboratory and clinical trials. The newest prostaglandin analogue, latanoprost (PhXA41), effectively lowered intraocular pressure and was well tolerated in clinical trials of up to 4 weeks' duration. Prostaglandins reduce intraocular pressure by enhancing uveoscleral outflow. Ethacrynic acid enhanced traditional outflow facility and lowered intraocular pressure when applied topically or intracamerally in laboratory studies and clinical trials. Corneal adverse effects of ethacrynic acid have been noted. Reformulation of ethacrynic acid ointment may resolve this problem. These 4 classes of compounds will enhance our options for the medical management of glaucoma. They may be used instead of or in combination with some of the drugs currently in use, and may be better tolerated.

Apraclonidine prophylaxis for postcycloplegic intraocular pressure spikes

A randomized, prospective, double-masked study was undertaken to determine the risk of postcycloplegic intraocular pressure spikes in patients with open-angle glaucoma and to evaluate apraclonidine prophylaxis in minimizing these spikes. Patients were stratified as miotic treated or untreated and each group was randomized to receive either placebo (artificial tears) or apraclonidine in both eyes before instillation of tropicamide. In both the miotic treated and untreated groups that received placebo, there was a high incidence, (37% and 38%, respectively) of clinically significant (greater than or equal to 6 mmHg) intraocular pressure spikes after instillation of tropicamide. In both the miotic treated and untreated groups, there was a statistically significant difference in postcycloplegic intraocular pressure between the subgroup that received placebo and the group that received apraclonidine prophylaxis (P = 0.003 and P = 0.006, respectively). Additionally, four eyes that received placebo had a spike of over 10 mmHg (range, 12 to 27 mmHg), while only one eye had an increase of greater than 10 mmHg (12 mmHg) in the apraclonidine group. Thus, apraclonidine appears to be a useful agent for minimizing precipitous increases in intraocular pressure after cycloplegia in eyes of open-angle glaucoma patients prone to this complication of cycloplegia.