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Six Tests for Glaucoma


Updated April 28, 2014

Glaucoma is an eye disease usually caused by having elevated pressure in the eye. Glaucoma can cause vision loss, often without any warning signs or symptoms. Regular eye exams, including specific diagnostic tests, are important for early detection of glaucoma. If diagnosed early enough, glaucoma can be properly managed to prevent major loss of vision. Following are six tests used to help detect glaucoma.

1. Tonometry

Tonometry is a very common test to measure the pressure inside the eye, also known as intra-ocular pressure (IOP). Having eye pressure higher than normal places a person at a higher risk for glaucoma. It is important to understand that having higher pressure than normal does not mean a definite diagnosis of glaucoma.

2. Ophthalmoscopy

Ophthalmoscopy is used to examine the inside of the eye. Ophthalmoscopy can be performed on a dilated or undilated eye. An eye doctor uses special magnifying lenses and medical devices to view the optic nerve. The color, shape and overall health of the optic nerve is important in glaucoma assessment. The doctor may also use a digital camera to photograph the optic nerve.

3. Gonioscopy

Gonioscopy is a test that uses a special mirrored device to gently touch the surface of the eye to examine the angle where the cornea meets the iris. Whether this angle is open or closed can tell the doctor what type of glaucoma is present, and how severe the glaucoma may be.

4. Visual Field Testing

Visual field testing, also known as perimetry, is a test that measures how sensitive a person's vision is. During a visual field test, you will look straight ahead at a small light or other target and will be asked to let the examiner know when you see a light flash off to the side in your peripheral vision. Most visual field testing today is computerized.

5. Nerve Fiber Analysis

Nerve fiber analysis is a newer method of glaucoma testing in which the thickness of the nerve fiber layer is measured. Thinner areas may indicate damage caused by glaucoma. This test is especially good for patients who may be considered to be a glaucoma suspect and also to indicate if a person’s glaucoma is progressively becoming worse.

6. Pachymetry

Pachymetry is the method of measuring the thickness of the cornea. Although research is still being conducted on the importance of corneal thickness, pachymetry is starting to play a larger role in glaucoma testing. The thickness of the cornea seems to influence the eye pressure reading when tonometry is performed.

Source: Eskridge, J. Boyd, Amos, John F., Jimmy D. Bartlett, "Clinical Procedures in Optometry." Copyright, 1991.

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