Primary Angle-Closure Glaucoma Medication

Updated: May 09, 2016
  • Author: Clement Chee-yung Tham, BM, BCh, MA, FRCS(Glasg); Chief Editor: Hampton Roy, Sr, MD  more...
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Medication

Medication Summary

The first step in the management of primary angle-closure glaucoma (PACG) is often a surgical procedure to open up, as far as possible, those segments of the drainage angle that are appositionally closed or narrow. Options may include laser peripheral iridotomy, argon laser peripheral iridoplasty, and lens extraction, depending on the mechanism(s) of angle closure. Intraocular pressure (IOP) may, however, remain increased after these procedures, which may be the result of extensive residual synechial angle closure. IOP-lowering medications are indicated if a safe IOP level cannot be reached after angle-opening procedures. [68]

In the past, timolol and pilocarpine were extensively used in PACG. Recent studies have demonstrated the superior IOP-lowering efficacy of prostaglandin analogue monotherapy over these conventional drugs, and even some combination therapies, in PACG. The IOP-lowering effect of prostaglandin analogues does not appear to be related to the degree of angle closure or to the extent of peripheral anterior synechiae (PAS). Once-daily prostaglandin analogue regimes are generally well tolerated by patients with PACG. Prostaglandin analogues have become an important member in the medical arsenal against PACG. [69]

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Miotic agents

Class Summary

These agents directly stimulate cholinergic receptors in the eye, decreasing resistance to aqueous humor outflow.

Pilocarpine ophthalmic (Isopto Carpine, Pilopine HS Gel)

Instillation frequency and concentration are determined by response. Individuals with heavily pigmented irides may require higher strengths.

If other glaucoma medication also is being used, at bedtime, use gtt at least 5 min before gel.

Patients may be maintained on pilocarpine as long as IOP is controlled and no deterioration in visual fields occurs.

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Beta-adrenergic Blocker

Class Summary

Thought to decrease IOP by reducing aqueous formation; however, some studies observed increased outflow.

Timolol ophthalmic (Betimol, Istalol, Timoptic, Timoptic-XE, Tiimoptic Ocudose)

May reduce elevated and normal intraocular pressure (IOP), with or without glaucoma by inhibiting inflow. Available in various solutions and gels with varying recommended application frequency.

The brands Timoptic XE and Istalol are both administered once daily. However, Timoptic XE is a gel-forming solution while Istalol is an aqueous solution.

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Prostaglandin, ophthalmic

Class Summary

Reduces IOP by increasing uveoscleral outflow.

Travoprost ophthalmic solution (Travatan Z)

Prostaglandin F2-alpha analog and selective FP prostanoid receptor agonist. Exact mechanism of action unknown but believed to reduce IOP by increasing uveoscleral outflow.

Latanoprost (Xalatan)

May decrease IOP by increasing outflow of aqueous humor.

Bimatoprost (Lumigan, Latisse)

Prostaglandin agonist that selectively mimics effects of naturally occurring substances, prostamides. Exact mechanism of action unknown but believed to reduce IOP by increasing outflow of aqueous humor through trabecular meshwork and uveoscleral routes. Used to reduce IOP in open-angle glaucoma or ocular hypertension.

Tafluprost (Zioptan)

Prostaglandin agonist that selectively mimics effects of naturally occurring substances, prostamides. Exact mechanism of action unknown but believed to reduce IOP by increasing outflow of aqueous humor through trabecular meshwork and uveoscleral routes. Used to reduce IOP in open-angle glaucoma or ocular hypertension.

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Carbonic anhydrase inhibitor

Class Summary

Inhibits aqueous humor formation by inhibiting carbonic anhydrase 2 (CA-II).

Brinzolamide (Azopt)

Catalyzes reversible reaction involving hydration of carbon dioxide and dehydration of carbonic acid. May use concomitantly with other topical ophthalmic drug products to lower IOP. If more than one topical ophthalmic drug is being used, administer drugs at least 10 min apart.

Dorzolamide (Trusopt)

Reversible carbonic anhydrase inhibitor that may decrease aqueous humor secretion, causing a decrease in IOP. Presumably, it slows bicarbonate ion formation with subsequent reduction in sodium and fluid transport.

Systemic absorption can affect carbonic anhydrase in the kidney, reducing hydrogen ion secretion at renal tubule, and increasing renal excretion of sodium, potassium bicarbonate, and water.

Used concomitantly with other topical ophthalmic drug products to lower IOP. If more than one ophthalmic drug is being used, administer the drugs at least 10 min apart.

Acetazolamide (Diamox Sequels)

Reduces rate of aqueous humor formation by direct inhibition of enzyme carbonic anhydrase (CA) on secretory ciliary epithelium, causing in turn a reduction in intraocular pressure (IOP). More than 90% of CA must be inhibited before IOP reduction can occur. May reduce IOP by 40-60%. Effects are seen in about an hour, they peak in 4 h, and trough in about 12 h. Derived chemically from sulfa drugs. If one form is not well tolerated, another form may be better or lower dose of the drug may be better tolerated.

Used for adjunctive treatment of chronic simple (open-angle) glaucoma and secondary glaucoma and preoperatively in acute angle-closure glaucoma when delay of surgery desired to lower IOP

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Alpha2-adrenergic agonist agent, ophthalmic

Class Summary

Reduces aqueous humor production and increases uveoscleral outflow.

Brimonidine (Alphagan P)

Relatively selective alpha2-adrenergic receptor agonist, decreases IOP by dual mechanisms. Reduces aqueous humor production and increases uveoscleral outflow. Has minimal effect on cardiovascular and pulmonary parameters. A moderate risk of allergic response to this drug exists. Caution should be used in individuals who have developed an allergy to Iopidine.

The brand Alphagan-P contains the preservative Purite and has been shown to be much better tolerated than its counterpart Alphagan.

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Diuretic, Osmotic

Class Summary

These agents elevate glomerular filtrate osmolarity, resulting in decreased tubular reabsorption of water, thereby inducing diuresis.

Mannitol (Osmitrol)

Reduces elevated intraocular pressure when the pressure cannot be lowered by other means.

Initially assess for adequate renal function in adults by administering a test dose of 200 mg/kg, given IV over 3-5 min. Should produce a urine flow of at least 30-50 mL/h of urine over 2-3 h.

In children, assess for adequate renal function by administering a test dose of 200 mg/kg, given IV over 3-5 min. Should produce a urine flow of at least 1 mL/kg over 1-3 h.

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