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Computerised Visual Fields

What is a visual field?

Your retina is made up of photoreceptors, which perceive the light entering the eye. This information is transmitted to the brain from each photoreceptor via the special nerve (glanglion) cells that make up the optic nerve.

The central area of the retina is the part that is most sensitive to light, which is why we see best what is directly in front of us. The peripheral areas of the retina are less sensitive, but they allow us some (less clear) vision of what surrounds the central area that we are looking at. The total area that you can see of the world around you is known as your visual field.

Any disruption in the function of the cells sending information from the retina to the brain will block the signal’s transmission, making that portion of the retina and the accompanying visual field less sensitive to light, and that area of your visual field more difficult or impossible to see.

Glaucoma is a disease in which the ganglion cells of the optic nerve can become damaged and die, at least partially due to the pressure within the eye. There are millions of these cells, however, and one can lose perhaps as many as 40 per cent of them before being aware of any visual loss. In fact, a small number of cells die every year naturally.

Testing the visual field

Visual field testing is an important part of the diagnosis and monitoring of diseases that can cause visual impairment. In computerised testing of the visual field, we analyse the light-sensitivity of the outer areas (periphery) of the retina, and of the peripheral visual field.

Abnormalities in or gradual loss of visual fields can indicate glaucoma, optic nerve disease, multiple sclerosis, brain tumours or many other diseases. While visual field testing is only part of testing for a diagnosis of glaucoma or another disease, it becomes very important for measuring the progress of a disease over time, informing its management and control.

At Heming Scott & Donald, we use advanced computerised visual field testing to assess the extent of your visual field.