Glaucoma: Screening & Diagnosis

If you’re at high risk for glaucoma, you should have a dilated pupil eye examination at least every one to two years. To help diagnose glaucoma, an ophthalmologist or optometrist will perform a comprehensive eye exam that may include the following tests:

Tonometry

This test measures the pressure inside the eye. Examples of tonometers include:

• The air puff or noncontact tonometer emits a puff of air. The test measures eye pressure by the eye's resistance to the air.
• The applanation tonometer touches the eye's surface after the eye has been numbed and measures the amount of pressure necessary to flatten the cornea. This is the most sensitive tonometer, but the cornea must be clear and regularly shaped for it to function properly.
• The electronic indentation method measures pressure by directly contacting anesthetized eyes with a digital pen-like instrument.

Pupil Dilation

Special drops temporarily enlarge the pupil so that the doctor can better view the inside of the eye.

Visual Field Testing

This test measures the entire area seen by the forward-looking eye to document straight-ahead (central) and side (peripheral) vision. It measures the dimmest light seen at each spot tested. Each time the patient perceives a flash of light, he or she responds by pressing a button.

Visual Acuity Test

This test measures sight at various distances. While seated 20 feet from an eye chart, the patient reads standardized visual charts with each eye, with and without corrective lenses.

Pachymetry

The eye doctor uses an ultrasonic wave instrument to help determine the thickness of the cornea and better evaluate eye pressure.

Ophthalmoscopy

The doctor examines the interior of the eye by looking through the pupil with a special instrument. This test can help detect damage to the optic nerve caused by glaucoma.

Gonioscopy

The doctor uses this instrument to view the front part of the eye (anterior chamber) to determine if the iris is closer than normal to the back of the cornea. This test can help diagnose closed-angle glaucoma.

Optic Nerve Imaging

Imaging helps document optic nerve changes over time. Nerve imaging techniques include:

• Stereo optic nerve photographs
• Scanning laser polarimetry (GDx)
• Confocal scanning laser ophthalmoscopy (Heidelberg Retinal Tomograph or HRT)
• Optical coherence tomography (OCT)

All four techniques are painless and noninvasive. Your doctor determines which method(s) to use, depending on your glaucoma condition.