Six Tests for Glaucoma

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.


Intraocular pressure testing for glaucoma. Westend61

Tonometry is a very common test to measure the pressure inside the eye, also known as intraocular 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. Although most people fall into a certain normal range, it is possible to have glaucoma with lower eye pressure and not to have glaucoma with higher pressures. What is more important is whether the pressure fluctuates up and down a lot and what that particular eye pressure is doing to your eye.


Boy getting an eye exam
Boy getting an eye exam. NEI/NIH

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. Sometimes, stereo photographs are taken to give a 3-dimensional picture in order to better assess the overall shape of the optic nerve. 


Dilating the pupil is part of a comprehensive eye exam.. be happy!

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. Gonioscopy can also be completed using optical coherence tomography.

Visual Field Testing

A visual field test

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. Visual field testing usually needs to be repeated several times before the doctor can make a valid assessment. 

Nerve Fiber Analysis

An image of the eye
An image of the eye. National Eye Institute

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.


Eye doctor examination the cornea.. IAN HOOTON/SPL
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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