The special procedure of measuring visual fields is called perimetry. It is specifically indicated in glaucoma and other neurologic conditions. It is an automated procedure, where a repeated light stimulus of varying intensities appears in different parts of the visual field. Fields are charted on the basis of patient’s perception of these lights, while his/her eye is focused on a central spot. The results obtained from the patient are then compared with those of the age matched normal population and the amount of damage is quantified.

It is a simple, painless outpatient procedure and takes approximately 15 minutes. This test is invaluable in diagnosing, and monitoring the treatment in patients with glaucoma. A patient typically requires multiple sittings of this investigation over a period of time to monitor the progression of the disease.

It is also useful in certain neurological conditions that may affect the optic nerve of the eye and can be used the quantify defects of some visually toxic medications.