Glaucoma Treatment

Glaucoma is a disease caused by increased intraocular pressure (IOP) resulting either from a malformation or malfunction of the eye’s drainage structures. Left untreated, an elevated IOP causes irreversible damage the optic nerve and retinal fibers resulting in a progressive, permanent loss of vision. However, early detection and treatment can slow, or even halt the progression of the disease.

What causes glaucoma?

The eye constantly produces aqueous, the clear fluid that fills the anterior chamber (the space between the cornea and iris). The aqueous filters out of the anterior chamber through a complex drainage system. The delicate balance between the production and drainage of aqueous determines the eye’s intraocular pressure (IOP). Most people’s IOPs fall between 8 and 21. However, some eyes can tolerate higher pressures than others. That’s why it may be normal for one person to have a higher pressure than another.

Common types of glaucoma

Open Angle

Open angle (also called chronic open angle or primary open angle) is the most common type of glaucoma. With this type, even though the anterior structures of the eye appear normal, aqueous fluid builds within the anterior chamber, causing the IOP to become elevated. Left untreated, this may result in permanent damage of the optic nerve and retina. Eye drops are generally prescribed to lower the eye pressure. In some cases, surgery is performed if the IOP cannot be adequately controlled with medical therapy.

Acute Angle Closure

Only about 10% of the population with glaucoma has this type. Acute angle closure occurs because of an abnormality of the structures in the front of the eye. In most of these cases, the space between the iris and cornea is more narrow than normal, leaving a smaller channel for the aqueous to pass through. If the flow of aqueous becomes completely blocked, the IOP rises sharply, causing a sudden angle closure attack.

While patients with open angle glaucoma don’t typically have symptoms, those with angle closure glaucoma may experience severe eye pain accompanied by nausea, blurred vision, rainbows around lights, and a red eye. This problem is an emergency and should be treated by an ophthalmologist immediately. If left untreated, severe and permanent loss of vision will occur in a matter of days.

Secondary Glaucoma

This type occurs as a result of another disease or problem within the eye such as: inflammation, trauma, previous surgery, diabetes, tumor, and certain medications. For this type, both the glaucoma and the underlying problem must be treated.

Congenital

This is a rare type of glaucoma that is generally seen in infants. In most cases, surgery is required.

Signs and Symptoms

Glaucoma is an insidious disease because it rarely causes symptoms. Detection and prevention are only possible with routine eye examinations. However, certain types, such as angle closure and congenital, do cause symptoms.

• Angle Closure (emergency)
• Sudden decrease of vision
• Extreme eye pain
• Headache
• Nausea and vomiting
• Glare and light sensitivity
• Congenital
• Tearing
• Light sensitivity
• Enlargement of the cornea

Detection and Diagnosis

• Because glaucoma does not cause symptoms in most cases, those who are 40 or older should have an annual examination including a measurement of the intraocular pressure. Those who are glaucoma suspects may need additional testing.
• The glaucoma evaluation has several components. In addition to measuring the intraocular pressure, the doctor will also evaluate the health of the optic nerve (ophthalmoscopy), test the peripheral vision (visual field test), and examine structures in front of eye with a special lens (gonioscopy) before making diagnosis
• The doctor evaluates the optic nerve and grades its health by noting the cup to disc ratio. This is simply a comparison of the cup (the depressed area in the center of the nerve) to the entire diameter of the optic nerve. As glaucoma progresses, the area of cupping, or depression, increases. Therefore, a patient with a higher ratio has more damage.
• The progression of glaucoma is monitored with a visual field test. This test maps the peripheral vision, allowing the doctor to determine the extent of vision loss from glaucoma and a measure of the effectiveness of the treatment. The visual field test is periodically repeated to verify that the intraocular pressure is being adequately controlled.
• The structures in the front of the eye are normally difficult to see without the help of a special gonioscopy lens. This special mirrored contact lens allows the doctor to examine the anterior chamber and the eye’s drainage system.

Treatment

• Most patients with glaucoma require only medication to control the eye pressure. Sometimes, several medications that complement each other are necessary to reduce the pressure adequately.
• Surgery is indicated when medical treatment fails to lower the pressure satisfactorily. There are several types of procedures, some involve laser and can be done in the office, others must be performed in the operating room. The objective of any glaucoma operation is to allow fluid to drain from the eye more efficiently.
• All glaucoma surgery procedures (whether laser or non-laser) are designed to accomplish one of two basic results: decrease the production of intraocular fluid (aqueous humor) or increase the outflow (drainage) of this same fluid. Occasionally, a procedure will accomplish both.
• Currently the goal of glaucoma surgery and other glaucoma treatment is to reduce or stabilize intraocular pressure (IOP). When this goal is accomplished, damage to ocular structures – especially the optic nerve- may be prevented.
• No matter the treatment, early diagnosis is the best way to prevent vision loss from glaucoma. See your eye care practitioner routinely for a complete eye examination, including a check of your IOP. People at high risk for glaucoma due to elevated intraocular pressure, family history, ethnic background, age or optic nerve appearance may need more frequent visits to the eye doctor.

When Is Glaucoma Surgery Needed?

• Depending on the type of glaucoma you have, different treatment options may be considered. Non-surgical options include the use of topical eye medications (glaucoma eye drops) or oral medications (pills).
• Most cases of glaucoma can be controlled with one or more drugs. But some people may require surgery to reduce their IOP further to a safe level by improving the outflow or drainage of fluids. Occasionally, surgery can eliminate the need for glaucoma eye drops. However, you may need to continue with eye drops even after having glaucoma surgery.
• Some recent studies indicate that a laser procedure known as selective laser trabeculoplasty (SLT) may be equally as effective as glaucoma eye drops for lowering internal eye pressure. This laser surgery might be considered a primary treatment, particularly for people who find it difficult to comply with the strict, regular schedule needed for administering eye drops.
• Another procedure called a trabeculectomy creates an artificial drainage area. This method is used in cases of advanced glaucoma where optic nerve damage has occurred and the IOP continues to soar. A third common option is a shunt, a device that a surgeon implants in your eye to improve fluid drainage.
• Laser surgery for glaucoma may be required to open drainage channels, which helps reduce high internal eye pressure.

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Laser Trabeculoplasty

To increase outflow of internal eye fluid, an ophthalmologist performs laser trabeculoplasty with a laser that creates tiny holes in the filtration angle of the eye, where the cornea and iris meet.

A newer procedure, selective laser trabeculoplasty, creates minimal heat damage to adjacent tissue, which generally means the procedure can be repeated safely. Laser trabeculoplasties are usually performed as an adjunct to a patient’s ongoing eye drop therapy. Studies are now investigating whether SLT could be used routinely as a first-line therapy for treatment of open-angle glaucoma and other types of glaucoma, even before eye drops are used.

Trabeculectomy, Trabeculotomy and Goniotomy

• Your eye doctor may recommend that a surgical incision be made into the eye’s drainage system to create new channels for more normal flow of fluid. To accomplish this goal, a trabeculectomy involves partial removal of the eye’s drainage system.
• Trabeculectomy is the most common surgical non-laser procedure performed for glaucoma when the IOP is no longer controlled by eye drops, pills or laser trabeculoplasties.
• A Trabeculectomy creates a “controlled” leak of fluid (aqueous humor) from the eye, which percolates under the conjunctiva. A small conjunctival “bleb” (bubble) appears at the junction of the cornea and the sclera (limbus) where this surgically produced valve is made.
• A trabeculotomy is the same as a trabeculectomy, except that incisions are made without removal of tissue.
• A goniotomy typically is used for infants and small children, when a special lens is needed for viewing the inner eye structures to create openings in the trabecular meshwork to allow drainage of fluids.

Iridotomy and Iridectomy

• In an iridotomy, a laser is used to create a hole in the iris to enhance the drainage passages blocked by a portion of the iris.
• An iridectomy involves surgically removing a small piece of the iris that will allow a better flow of fluid in eyes with narrow-angle glaucoma.

The Future of Glaucoma Treatment

• Glaucoma specialists have differing viewpoints about the use of drug, laser and surgical intervention to control high IOP.
• Some glaucoma specialists, for example, say that long-term costs of drug treatments involving eye drops can be an economic burden that may be offset with the use of laser treatments.
• Others argue that treatments such as eye drops are far less invasive, are generally effective and have fewer risks of complications than laser or non-laser surgical approaches. Study results comparing long-term effectiveness of different treatments also vary

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