Visual fields

Right eye – visual field

This is a “map” of the entire area that the retina normally sees, even at the edges of vision, (known as “peripheral vision”).

It is measured by Optometrists or Ophthalmologists, either as a regular part of the eye examination, especially after the age of 40, or if a person notices a change in his/ her vision.

Testing the visual fields, demonstrates how much “side”, or peripheral vision a person has, in particular, (although it refers to the entire area of vision of each particular eye).

The fields of the two eyes overlap giving an overall horizontal field of 160 to 170 degrees for binocular (“2 – eyed”) vision.

This can roughly be assessed by the clinician by the “confrontation” method, where the person keeps their eye fixed on the examiner’s nose, and tells the examiner when a moving finger is detected, moving from the periphery.

This is tested horizontally and vertically.

Abnormal blind spots may show up on this test as well. A blind spot results from the absence of visual receptors in part of the retina. We all have a natural “blind spot” in each eye and this is at the part of the retina where the optic nerve enters the eye, and where there are no rods or cones. Abnormal blind spots occur when there is damage to the retina, for a variety of reasons.

The discovery of abnormal blind spots or reduced peripheral vision may be the first indication of glaucoma, and this is why it is routinely tested for, by Opticians.