How is Glaucoma Diagnosed ?

An eye doctor (ophthalmologist) can usually detect those individuals who are at risk for glaucoma (because of, for example, a narrow filtering angle or increased intraocular pressure) before nerve damage occurs. The doctor also can diagnose patients who already have glaucoma by observing their nerve damage or visual field loss. The following tests, all of which are painless, may be part of this evaluation.
 

Tonometry

determines the pressure in the eye by measuring the tone or firmness of its surface.

Applanation

Pachymetry

Pachymetry determines the thickness of the cornea.. Recent studies have shown that central corneal thickness can affect the measurement of intraocular pressure. Thicker corneas may give falsely high eye pressure readings and thinner corneas may give falsely low pressure readings. Furthermore, thin corneas may be an additional risk factor for glaucoma.

Gonioscopy.

The mirrors enable the doctor to view the interior of the eye from different directions. The purpose of this test is to examine the filtering angle and drainage area of the eye. In this procedure, the doctor can determine whether the angle is open or narrow. As indicated earlier, individuals with narrow angles have an increased risk for a sudden closure of the angle, which can cause an acute glaucomatous attack. Gonioscopy can also determine if anything, such as abnormal blood vessels, might be blocking the drainage of the aqueous fluid out of the eye.

Visual Field Ttesting

It actually maps the visual fields to detect any early (or late) signs of glaucomatous damage to the optic nerve. This test can be done by having the patient look straight ahead and count the fingers shown by the examiner from the side. More typically, however, visual fields are measured by a computerized assessment. For this procedure, one eye is covered and the patient places his or her chin in a type of bowl. Then, when the patient sees lights of various intensities and at different locations, he or she pushes a button. This process produces a computerized map of the visual field.
 

Nerve Fiber Layer Analysis

This is important test for earliest detection of glaucoma where thickness of retinal nerve fiber layer is measured. Since nerve layer fiber is earliest site of damage this test assumes importance in detecting glaucoma at earliest stage so that it can be treated early to arrest or slowdown further damage to the nerve. We have OCT (RTVue 100 ,USA) and GDxVCC (Carl Zeiss,Germany) for this test.