Insight into Glaucoma: Protecting Your Vision
Patients with glaucoma-a group of diseases of the eye that cause damage to the optic nerve-may have questions about risk factors, diagnosis, and treatment options.
Patients with glaucoma—a group of diseases of the eye that cause damage to the optic nerve—may have questions about risk factors, diagnosis, and treatment options.
Glaucoma is a group of diseases of the eye that cause damage to the optic nerve (the bundle of nerve fibers that carry information from the eye to the brain). The condition may develop in 1 or both eyes and can initially lead to loss of side (peripheral) vision and, if left untreated, blindness. In the majority of cases, damage to the optic nerve is caused by an increase in eye pressure, also known as intraocular pressure. Glaucoma can also occur if the eye pressure is normal. As the optic nerve becomes more damaged, blank spots may appear in your field of vision.
Glaucoma is considered to be one of the leading causes of blindness, especially among African Americans and Hispanics. In the United States, an estimated 4 million people have glaucoma. An estimated 67 million people worldwide have the condition. More than half of the people who have glaucoma are not aware of it, because the disease often has no symptoms in the early stages. The rate of glaucoma increases around the age of 65 years; however, it may occur at any age.
The 2 most common forms of glaucoma are open-angle and angle-closure. Other types of glaucoma include normal tension and congenital glaucoma. Both open-angle and angleclosure glaucoma can be classified as primary or secondary conditions. If the cause is not known, it is called primary glaucoma. If the cause is known, it is referred to as secondary glaucoma, such as with an eye injury, inflammation, advanced cataracts, or diabetes.
Open-angle glaucoma accounts for an estimated 95% of glaucoma cases and has no symptoms at first; however, side vision gradually decreases until, at some point, side vision disappears altogether. If left untreated, gradual vision loss or blindness may result. Although there are often no symptoms, a complete eye exam may detect the condition. Most cases of open-angle glaucoma react well to treatment with medication if caught early and treated.
Angle-closure glaucoma (also referred to as closed-angle glaucoma) is responsible for an estimated 10% to 15% of glaucoma cases. This type of glaucoma occurs when the normal flow of the aqueous humor (fluid in the eye) between the iris (the colored part of the eye around the center) and the lens is blocked. This typically occurs in those people with a structural defect that causes a narrow angle between the iris and the cornea. Angle-closure glaucoma is considered a medical emergency, because without proper treatment, people can lose their sight in as little as 1 to 2 days. Individuals with this type of glaucoma experience a sudden increase in eye pressure and may have symptoms such as severe eye pain, nausea, blurred vision, redness of the eye, and seeing a rainbow halo around lights. If you experience any of these symptoms, you should seek treatment immediately. Prompt and proper treatment, including laser surgery and medications, may clear any blockage and preserve eyesight.
Risk Factors for Open-Angle Glaucoma
Although glaucoma can affect anyone, certain factors may increase an individual’s risk of developing the condition. Glaucoma is 6 to 8 times more common in African Americans than among Caucasians. Risk factors include:
• Family history of glaucoma
• Elevated eye pressure
• 40 years of age or older and African American
• 60 years of age or older among the general population
• African, Asian, or Hispanic ancestry
• Having uncontrolled diabetes and/or hypertension
• History of migraines
• Physical injury to the eye
• Previous eye surgery
• Routine or long-term use of corticosteroids
• Having severe nearsightedness
• Having thinner central cornea thickness
Testing for Glaucoma
To detect glaucoma during a complete eye exam, your doctor will measure your eye pressure, using an instrument known as a tonometer; test both central and side vision; measure visual clearness by using an eye chart; determine the thickness of the corneal area; examine the interior and front part of the eyes; and take an image of the optic nerve.
If left untreated, glaucoma can cause progressive vision loss and eventually blindness. Although no cure exists for glaucoma and any damage to an individual’s vision that has occurred is irreversible, various treatments are available. These treatments include eye drops, sometimes oral medications, laser therapy, and/or surgery, or a combination of these therapies. In general, medications used for glaucoma are indicated to reduce increased eye pressure and prevent damage to the optic nerve.
Various eye drops are available for the management of glaucoma. The types of eye drops include medications known as beta-blockers (timolol, levobunolol, and carteolol), prostaglandins (latanoprost, bimatoprost, and travoprost), alphaadrenergic drops (brimonidine and apraclonidine), cholinergic agents (pilocarpine), and carbonic anhydrase inhibitors (dorzolamide and brinzolamide). Some of these eye drops are available as combination products as well. Your doctor will determine which eye drop is best for you. You should discuss the required dose, dosing intervals, and possible side effects with your physician or pharmacist. You should tell your doctor about any allergies, other medical conditions that you may have, and if you are currently taking any medications, including prescription, over-the-counter drugs, nutritional supplements, and alternative or homeopathic products. This information is crucial in preventing any possible drug—drug interactions or contraindications.
In order for eye drops to be effective, it is important that you understand how to properly administer the eye drops. Recommended steps for eye drop administration include:
• If you use both eye ointments and eye drops, always use the drops first.
• Always wash hands before applying drops.
• Tilt the head back and with one hand and pull down the lower eyelid to form a pocket.
• With the other hand, hold the bottle as close to the eye as possible without actually touching the eye. Apply drop of medication.
• After the drop has been applied, close the eye for at least 1 minute to prevent the drop from draining out.
• If another drop from another medication is needed, wait at least 5 minutes before administering another drop.
• Wash hands after administering the drops. Store medication in a proper place.
More detailed information on administering eye drops can be found on the Glaucoma Research Foundation Web site at www.glaucoma.org/treating/eyedrop_tips_1.php. Some individuals may require surgery, especially if medication is not sufficient or not tolerable. Final Thoughts In addition to medication for therapy, it is important that you maintain routine checkups with your eye specialist and get an eye examination, including dilation, at least every 1 to 2 years or as directed by your health care provider. The American Academy of Ophthalmology currently recommends that individuals with no signs or risk factors for eye disease should get a baseline eye screening exam at the age of 40.
For the treatment to be effective, it is important for you to adhere to the treatment prescribed for the management of your glaucoma and to take your medications as directed. If you experience any adverse effects, you should discuss these with your health care provider. Because glaucoma and some of the medications used for glaucoma can make your eyes very sensitive to light and glare, you may want to use sunglasses to help protect your vision. Your sunglasses should block at least 99% of UVB rays and 95% of UVA rays. Although a diagnosis of glaucoma may seem overwhelming, the majority of cases of glaucoma can be successfully managed with early detection, proper treatment, and routine monitoring. â–
For more information on glaucoma, please visit the following Web sites:
• Glaucoma Research Foundation Web site: www.glaucoma.org
• The Glaucoma Foundation Web site: www.glaucomafoundation.org
• American Glaucoma Society Web site: www.glaucomaweb.org
• National Eye Institute Web site: www.nei.nih.gov/nehep
• American Academy of Ophthalmology Web site: www.aao.org/eyesmart/
• American Optometric Association Web site: www.aoa.org
Ms. Terrie is a clinical pharmacy writer based in Haymarket, Virginia.