Screening for Glaucoma
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The purpose of screening is early diagnosis and treatment. Screening tests are usually administered to people without current symptoms, but who may be at high risk for certain diseases or conditions. Since glaucoma usually has no symptoms and can occur in anybody regardless of risk factors, everybody should be screened for the disease as recommended by their physician.
Regular eye exams by an eye care professional are the best way to screen for glaucoma. Because most people experience no symptoms with glaucoma, it is important to schedule a regular eye exam. The frequency depends on your age, risk factors, and general health. See the screening guidelines below.
During your eye exam, your eye care professional may do the following tests:
Visual acuity —This test measures how well you see at various distances. You will be asked to look at a chart of letters or numbers and identify what you see.
Tonometry —This test measures the pressure inside the eye. There are several types of tonometry; in air tonometry, a puff of air is blown onto the cornea to take the measurement. Another type uses a small plastic device (Goldman tonometer) that lightly pushes against your eye in order to measure your intraocular pressure. For this test, the eye is first numbed with an eye drop, so you do not feel anything.
Gonioscopy —The eye care professional can see the drainage angle of your eye using a special lens. This can help determine if you are at risk for closed-angle glaucoma.
Pupil dilation —Drops are put in your eyes that enlarge/dilate your pupils. This allows the eye care professional to see more of the inside of your eye. Your close-up (near) vision may remain blurred for several hours afterwards and you may be sensitive to bright light. Ask your doctor for a pair of sunglasses after the dilation.
Ophthalmoscopy —Once your pupils are dilated, the eye care professional will examine your optic nerve and the rest of your retina with an instrument called an ophthalmoscope. The color and appearance of the optic nerve may indicate if damage from glaucoma is present and how extensive it is. Your doctor will probably take pictures of your optic nerve for future comparison.
Perimetry (visual field test) —This test produces a map of the complete field of vision. It is used to check whether there is damage to any area of vision. Since glaucoma slowly affects your peripheral, or side vision, you may not know you have any problems until detected on this test.
Pachymetry —Your physician may measure the thickness of your cornea using a special machine called a corneal pachymeter.Your eye is numbed with a drop first and it does not hurt.
Nerve Fiber Layer Analysis —Your doctor may use a special machine, such as an OCT, GDx, or HRT, to measure the thickness of the nerve fiber around your optic nerve. This can often be compared to normative data from other people without glaucoma of your age, sex, and race. It also can be rechecked in the future to see if there is any loss of nerve fiber thickness with time.
Ask your doctor for guidelines specific for your individual situation. The American Academy of Ophthalmology recommends the following general screening guidelines healthy adults with no risk factors for eye disease:
- At least once between age 20-29
- At least twice between age 30-39
- Age 40-64: every 2 to 4 years
- Age 65 and older: every 1 to 2 years
You should be screened more often, or as directed by your doctor, if you:
- Have risk factors for glaucoma or other eye diseases
- Have a family member who has glaucoma
- Have a personal or family history of eye disease
- Are African American or African heritage or of Latin heritage
- Have had a serious eye injury in the past
- Had eye surgery in the past
- Are taking a corticosteroid medication
- Have diabetes, ]]>high blood pressure]]> , or other chronic illness
Cautionary Note: If you currently have eye symptoms, you should call your provider immediately for an evaluation. In case of an emergency, call for an ambulance immediately.
American Academy of Ophthalmology website. Available at: http://www.aao.org/ .
Friedman DS, Wolfs RC, O'Colmain BJ, et al. Prevalence of open-angle glaucoma among adults in the United States. Arch Ophthalmol. 2004;122:532.
Glaucoma Research Foundation website. Available at: http://www.glaucoma.org/
National Eye Institute website. Available at: http://www.nei.nih.gov/ .
Weinreb RN, Khaw PT. Primary open-angle glaucoma. Lancet. 2004;363:1711.
Last reviewed June 2008 by ]]>Marcin Chwistek, MD]]>
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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