Changes in vision

Brain tumour symptoms can include changes to vision, such as blurred or double vision, abnormal eye movements, restricted field of view and more, but it is important to remember that brain tumours are relatively rare.

This means it is likely that your symptoms are NOT due to a brain tumour. However, it is always important to get any symptoms checked out at an opticians.

How might changes in vision show themselves?

Changes in vision associated with brain tumours can include blurred vision - for example, you may find it has become difficult to watch TV or read.

You may get a fleeting loss of vision lasting a few seconds ('greying out') related to changes in your posture, such as suddenly standing up.

Or you may find you have lost part of your field of vision. This could lead to you bumping into objects, or you could feel as if objects or people are suddenly appearing on one side of you.

Why can brain tumours cause changes in vision?

Changes in vision, as mentioned above, can be due to the optic disc at the back of your eye becoming swollen as a result of the increased pressure in the skull. The optic disc is the point on the retina where the optic nerve enters the eye from the brain (the retina is the layer of light-sensitive cells at the back of the eye.)

Optic disc swelling can be caused by a number of conditions, but when it is due to raised intracranial pressure (ICP), it is known as papilloedema. Papilloedema can be picked up by opticians during normal eye examinations. This can be important as people don't usually experience the visual symptoms in the early stages of papilloedema.

Not all patients with raised intracranial pressure develop papilloedema - this depends on the location and size of the tumour. Also patients who have previously had papilloedema may not develop it in the future.

Symptoms due to tumour position

Symptoms of a brain tumour can vary depending on the tumour's location, and several areas of the brain play a part in an aspect of vision.

Occipital lobe

The occipital lobe is the main area involved with vision. It processes the information coming from your eyes, so that you can understand what you see.

A tumour in the occipital lobe causes difficulties with vision, such as visual loss, or identifying objects or colours. Alternatively, it may cause loss of vision on one side.

Parietal lobe

Damage to the parietal lobe can cause difficulty with:

  • Bringing together information from your different senses (touch, vision, hearing, smell, taste) and making sense of it e.g. a person may bump into furniture that they have seen, but have misjudged where it is in relation to themselves.
  • Co-ordinating movements
  • Spatial awareness e.g. judging distances, hand-eye co-ordination
  • Speaking, understanding words, writing and reading. It can also cause numbness on the opposite side of the body from where the tumour is.

Cerebellum

Damage to the cerebellum can cause flickering of the eyes, as well as problems with balance, a loss of co-ordination, difficulty walking and speaking, vomiting and a stiff neck. It can also affect the fine co-ordination of the muscles leading to problems with dexterity (skills in using your hands).

Brain stem

For tumours in the brain stem, symptoms can include double vision, as well as unsteadiness and difficulty walking, facial weakness and difficulty speaking or swallowing.

Temporal lobe

A tumour in the temporal lobe can affect the ability to recognise objects, as well as identifying emotions in others, hearing, memory and learning.