VisionAware

Edited by Sefy Paulose, M.D., March, 2022

Glaucoma is a chronic condition that must be monitored for life. With proper monitoring and compliance with treatment, glaucoma can be managed to minimize any limitations to your vision or lifestyle.

Prostaglandin Analogs
Carbonic Anhydrase Inhibitors
Alpha-Adrenergic Agonists
Beta-Adrenergic Blockers
Combination Drugs
Bottle Cap Colors
Complying with Your Eye Medication Regimen
Laser Treatment
Surgery
Surgical Alternatives
Alternative Treatments, Clinical Trials, and Research

Prostaglandin Analogs

Prostaglandin analogs are the most widely prescribed eye drops. Prostaglandin is a naturally-occurring blood protein that can lower intraocular (within the eye) pressure, in addition to having many other therapeutic effects. Analogue, or “analogous,” means that the drug is comparable, or similar, to prostaglandin, but has a slightly different chemical composition.

Thus, prostaglandin analogues (PGAs) are drugs that are used in the treatment of open-angle glaucoma or ocular hypertension. These medications work by increasing the outflow or drainage of the aqueous humor from the eye and thus decrease intraocular pressure.

Some of the more common PGAs include

• Travatan (generic name: travoprost)
• Xalatan (generic name: latanoprost)
• Lumigan (generic name: bimatoprost)
• Zioptan (generic name: tafluprost)

Carbonic Anhydrase Inhibitors

Carbonic anhydrase inhibitors are pharmaceutical substances that repress the action of carbonic anhydrase, which is an enzyme that plays a major role in regulating pH and fluid levels in the human body. Carbonic anhydrase inhibitors reduce the body’s uptake of bicarbonate ions and decrease salt absorption, which has the effect of lowering fluid levels in the body.

Thus, carbonic anhydrase inhibitors (CAIs) are drugs that decrease pressure in the eye by reducing the fluid production of the eye itself.

These medications include the following:

• Trusopt (generic name: dorzolamide hydrochloride)
• Azopt (generic name: brinzolamide)

If additional medication is needed to control eye pressure, carbonic anhydrase inhibitors are also prescribed in oral, or pill, forms. These oral medications include

• Diamox (generic name: acetazolamide)
• Neptazane (generic name: methazolamide)

The pill form may also be prescribed for people who are not able to tolerate eye drops.

Alpha-Adrenergic Agonists

These drugs decrease intraocular pressure by reducing the production of aqueous humor and also increasing the outflow of the fluid.

These medications include the following:

• Alphagan (generic name: brimonidine tartrate)
• Iopidine (generic name: apraclonidine hydrochloride)

Beta-Adrenergic Blockers

These drugs reduce the production of aqueous humor and thereby reduce intraocular pressure. They are well-tolerated and are effective. However, your doctor may avoid them if you have asthma or slow heart rate (bradycardia).

These medications include the following:

• Timoptic (generic name: timolol maleate)
• Betimol (generic name: timolol hemihydrate)
• Betagan (generic name: levobunolol hydrochloride)
• Betoptic (generic name: betaxolol hydrochloride)
• Ocupress (generic name: carteolol)

Combination Drugs

Combination drugs combine two medications into one formulation, including

• Cosopt (combining dorzolamide hydrochloride and timolol maleate)
• Combigan (combining brimonidine tartrate and timolol maleate)
• Simbrinza (combining brinzolamide and brimonidine tartrate)

Bottle Cap Colors

If you use more than one type of eye drop, you may need to take each medicine in a certain order. You can use the color of the bottle cap to help you keep track of each type of eye drop:

• Prostaglandin analogues have turquoise bottle caps.
• Carbonic anhydrase inhibitors have orange bottle caps.
• Alpha-adrenergic agonists have purple bottle caps.
• Beta-adrenergic blockers have yellow or blue bottle caps.
• Combination drugs usually have blue bottle caps.

 

A listing of color codes for topical ocular medications

Complying with Your Eye Medication Regimen

If you have been diagnosed with glaucoma, it is critical that you follow the eye medication regimen prescribed by your ophthalmologist. In order for the medication to lower your intraocular pressure effectively, consistent daily adherence to your prescribed eye drop regimen is essential.

At times, compliance can be difficult because there can be some discomfort when administering your eye drops.

One tip for this problem is to refrigerate your drops. By refrigerating them, the drops will be cool and feel soothing on instillation. Another benefit of refrigerating your drops is that you will feel when they go in giving you assurance that you have properly administered your eye drops. If you have ongoing problems, such as pain, blurred vision, or headaches after taking your drops, talk to your doctor about using another type of eye drop. For additional/alternative techniques, adaptations, and assistive devices to help you take your glaucoma medications, see Tips for Taking Glaucoma (and Other) Eye Drops. 

Helpful Steps for Administering Drops (National Eye Institute)

• Always wash your hands before you begin.
• Tilt your head back.
• Hold the bottle upside down.
• Hold the bottle in one hand and place it as close as possible to your eye.
• Be careful not to let the tip of the dropper touch any part of your eye.
• With the other hand, pull down your lower eyelid. This forms a “pocket.”
• Place the prescribed number of drops into the lower eyelid pocket. If you are using more than one eye drop, be sure to wait at least five minutes before applying the next eye drop.
• Close your eye or press against the lower lid lightly with your finger for at least one minute. Either of these steps keeps the drops in the eye and helps prevent the drops from draining into the tear duct, which can increase your risk of side effects.

Either of these steps keeps the drops in the eye and helps prevent them from draining into the tear duct, which can increase your risk of side effects.

Laser Treatment

If eye drop medications do not adequately control the glaucoma, your doctor may consider a laser treatment as the next step. The type of laser procedure will vary based on the type of glaucoma you have. Ultimately, the laser treatment will lower pressure by increasing the drainage of the fluid from the eye. The procedure is relatively short, essentially painless, and usually performed in the doctor’s office at a specifical microscope called the slit lamp. First, they will instill an anesthetic on the surface of your eye, and they will use a special large contact-like lens so that your doctor can focus on the structure they need to laser. This laser is different from the laser surgery you may have heard for refractive errors such as LASIK and PRK.

There are various kinds of laser treatments, Each kind is specific to the type of glaucoma you have – angle closure glaucoma vs open angle glaucoma.

Laser peripheral Iridotomy (LPI)

This laser creates a small hole in the outskirts of the iris to provide an alternative pathway for aqueous to pass into the back of the eye. This allows the angle to be less narrow.

Peripheral Iridoplasty (or gonioplasty)

• This laser treats a layer of the peripheral iris stroma which ultimately expands the drainage system of the eye. By doing so, the angle of the eye will be less narrow

Laser trabeculoplasty (LTP)

In this procedure, laser energy is directed at the trabecular meshwork, which is the drainage system of the eye. The laser treatment lowers pressure by increasing the drainage of the fluid from the eye. There are various types of lasers that can be used. A few are the following:

• Argon laser trabeculoplasty (ALT) has been used for more than two decades.
• Selective laser trabeculoplasty (SLT) is a newer laser treatment
• Micropulse laser trabeculoplasty (MLT) is another newer laser treatment

Side effects from all types of lasers include mild inflammation in the eye and a possible temporary pressure rise. A short course of a mild steroid or non-steroidal anti-inflammatory eye drop is used to treat any resulting inflammation.

Surgery

Surgery to treat glaucoma is usually only undertaken as a final step for those patients who have not achieved adequate pressure control with either eye drop medications or laser treatment.

Depending on the type of glaucoma and associated risk factors, two basic types of surgeries are available:

• Filtering Surgery: Trabeculectomy: In a trabeculectomy, a small incision is made in the sclera (the white of the eye). Fluid slowly leaks from this incision into a “bleb,” which is a covered space made in the conjunctiva (the thin, transparent tissue that covers the outer surface of the eye). The fluid in the bleb is slowly reabsorbed by the eye. This surgery provides a “natural” alternate drainage for aqueous to flow out of the eye.
• Drainage Device Surgery: Drainage device surgery partially inserts an artificial tube implant into the eye. Fluid drains through the tube and out to a reservoir. This surgery provides an “artificial” alternate drainage for aqueous to flow out of the eye.

Both types of surgeries have been proven effective in lowering eye pressure. Some patients may still need to use post-surgery eye drop medications to maintain healthy eye pressure.

Surgical Alternatives

Recently, several surgical options other than those mentioned above have been developed:

• Express mini-shunt: A small stainless steel device the size of a grain of rice is implanted in the eye to drain the fluid.
• Trabectome: A device is inserted into the eye through a very small incision at the edge of the cornea. A small portion of the eye’s trabecular meshwork, which is responsible for fluid outflow, is removed, which improves drainage. This is usually done as part of cataract surgery.
• Canaloplasty: An incision is made in the eye and a microcatheter is inserted into the eye drainage system to encourage fluid outflow. This is usually done as part of cataract surgery.
• Other newer procedures are called MIGS (minimally invasive glaucoma surgeries) and are drawing lot of attention from eye surgeons. The currently available iStent is very small and recommended for use at the time of cataract surgery.

You can find more information about these surgical procedures at the Glaucoma Research Foundation.

Alternative Treatments, Clinical Trials, and Research

The Glaucoma Research Foundation has posted information on alternative treatments for glaucoma, as well as a discussion of medical marijuana’s usefulness in treating glaucoma. Marijuana has not been approved in the treatment of glaucoma due to its short-lived effect on intraocular pressure lowering. However, there is ongoing research in this field.

A great deal of research is taking place in the glaucoma field in topics ranging from identifying the genes that cause glaucoma to finding better treatments to manage and monitor intraocular pressure and protect the optic nerve.  You can visit the National Eye Institute and the Glaucoma Research Foundation for information about clinical trials.

Also see VisionAware’s Patient’s Guide to Living with Glaucoma and Guía del Paciente: Vivir con Glaucoma.