Diagnosis
A diagnosis of glaucoma no longer simply relies on the presence of pressure within the eye. It requires that there be optic nerve damage or a strong suggestion of damage, which can be clearly seen during a dilated eye examination of the optic nerve. In general, the hallmark sign of this condition is a loss of peripheral vision. With peripheral vision loss a person can see in front of him- or herself but has lost the vision to the side.
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| The optic nerve carries the information of vision from the eye to the brain. |
Because chronic glaucoma has no warning symptoms, half of its victims are unaware that they have the condition. Early diagnosis, however, is the key to successful treatment of glaucoma. One study reported that the more years since the last visit to an eye professional, the greater the risk for having visual loss.
Recommendations for Glaucoma Screening
- Everyone over age 65 and African Americans over 40 years old should have periodic eye exams, including tests for glaucoma, every other year.
- African Americans between ages 20 and 39 should have eye examinations every 3 to 5 years.
- Other people at higher risk (people with diabetes, history of eye injuries, a family history of glaucoma, or those taking corticosteroid medications) should have eye examinations every year after age 35.
- People with known glaucoma should have frequent examinations to check peripheral vision and to be sure treatment is maintaining a safe eye pressure. After such examinations, the ophthalmologist will assess current treatment and make necessary adjustments.
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Tonometry and Pressure Tests
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Doctors determine the intraocular pressure (IOP) of the aqueous humor inside the eye using tonometry, which measures the force necessary to make an indentation in the eye. There are several methods:
- In the Schiotz method, the doctor first anesthetizes the eye with drops, then presses very lightly against it with tonometer, a tiny smooth instrument that is used to measure the pressure.
- In the applanation method, the doctor touches a strip of orange-dyed paper to the side of the eye. The stain helps with the examination and rinses out with tearing. The doctor uses a slit-lamp, which is moved forward toward the patient's face until the tonometer touches the eye.
- The noncontact approach applies a puff of air and measures the force needed to indent the eye.
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