Pilocarpine is used in the long-term treatment of glaucoma; it is generally administered as a 0.5% to 4.0% aqueous solution four times per day. It is the standard cholinergic agent for treatment of open-angle glaucoma. During episodes of acute primary angle-closure glaucoma with pupillary block, 1% or 2% pilocarpine is administered two or three times over a 30-minute period to produce miosis once IOP has been lowered by secretory supressants and hyperosmotic agents to the point where iridial blood flow has been restored. Miosis pulls the peripheral iris away from the TM, thereby allowing aqueous humor to leave the eye. The miotic action of pilocarpine is also occasionally utilized to overcome the mydriasis produced by anticholinergics or sympathomimetics. Alternated with mydriatics, pilocarpine is employed to break adhesions between the iris and the lens. Pilocarpine has been used in the treatment of Adie's syndrome.27 Prolonged drug delivery may be accomplished through the use of polymer emulsions28 or gels.29,30
Carbachol in 0.75% to 3.0% solution is used three times daily to decrease IOP in open-angle glaucoma. The 0.01% solution (0.5mL) is given intracamerally at the conclusion of cataract surgery to prevent postsurgical IOP elevation or to produce miosis during ocular surgery.
Because of its toxicity, echothiophate should be reserved for patients with one of the following conditions:
1. Open-angle glaucoma not satisfactorily controlled with short-acting miotics and other agents
2. Primary open-angle or nonuveitic secondary open angle glaucoma
4. Accommodative esotropia, because echothiophate enhances the cyclotonic effect of parasympathetic neuronal input to the ciliary muscle, necessitating less input to achieve accommodation and thus stimulating less accommodation-linked convergence
Echothiophate iodide is marketed as a powder accompanied by a separately packaged diluent; the two are mixed for clinical use. The 0.03% solution is the most commonly employed strength for treatment of open-angle glaucoma and accommodative esotropia. Demecarium bromide is available as 0.125% or 0.25% solutions and is applied once or twice a day.
Table 5.1 summarizes the cholinergic drugs used to treat glaucoma.
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