Visual Field Test (Perimetry)


The field of vision is that portion of space in which objects are visible at the same moment during steady fixation of gaze in one direction. Various visual field tests using advanced "Humphrey perimeter" are performed at Tehran-Iran Noor Eye Hospital.

Perimetry is the main test to detect glaucoma and track any visual changes over time. It also helps diagnose various types of neurological diseases and visual pathways through the brain.

If your ophthalmologist recommends perimetry for you, it means that your optic nerve is suspected; this may be due to ocular or neurological problems, the most common and important of them are elevated intraocular pressure (such as glaucoma), damage to the optic nerve pathway, Increased cerebrospinal fluid pressure and optic neuritis (inflammation of the optic nerve).

A visual field test is an eye examination performed clinically by asking the patient to follow a moving object like a pen with eyes while keeping the head still.

In this examination, we quantify the visual angle that a person is able to see and understand the object as the patient's peripheral visual field. If the visual field testing is performed by computers, the diagnosis will be accurate and reliable. A perimeter, with a hemisphere shaped bowl (hollow sphere), is the systematic measurement of differential light sensitivity in the visual field by the detection of the presence of ligth stimuli on a white screen.

Perimetry Methods

This test has three methods:

1. Kinetic perimetry

In this method the light stimuli move inside a spherical hallow bowl, in front of the patient, to see them.

 2. Static perimetry

 The location of each ligth stimulus is constant and requires the observer to press a special button to see those points.

3. Humphrey

Humphrey is the most commen automated visual field Analyser used for perimetry. This assessment is conducted regularly in people who are taking "hydroxychloroquine" because of rheumatic disease or lupus (due to the possibility of deposition of chloroquine on the retina) at regular intervals of six months. Iran-Tehran Noor Eye Hospital offers all these services with the best quality to patients.