Tunnel vision

Peripheral vision is the part of your vision that lies beyond your central vision point – what we see at the side of your vision. Tunnel vision refers to the deterioration or loss of peripheral vision and can be temporary or permanent. As the name suggests, it can look as if you are looking through a tunnel.

Tunnel vision can be particularly dangerous in conditions such as driving or cycling, because without full peripheral vision you won’t be able to recognise potential hazards unless they are right in front of you. So if you are experiencing any symptoms of tunnel vision, it is important to be checked by your GP or an eye specialist as soon as possible.

Without side vision, it will look as if you are looking through a tunnel. So you will only be able to see objects in a small area directly in front of you.

There are many possible causes of tunnel vision, and this list is not exhaustive.

• Retinal damage – the outer part of the retina forms our peripheral vision – any damage to this part of the retina results in loss of vision in that area. Retinitis pigmentosa is a very rare genetic disease known to cause tunnel vision.
• Optic nerve damage – The optic nerve is responsible for sending signals from the eyes to the brain to reproduce the images we see. Damage to the optic nerve can lead to tunnel vision.
• Glaucoma is a common eye disease that affects the optic nerve, with symptoms including a slow loss of peripheral vision. If left untreated, it can lead to the development of tunnel vision, which is why regular eye health checks are so important.
• Brain damage – blood loss in the brain or stroke can also cause peripheral vision loss.
• Temporary tunnel vision – in times of extreme panic, stress or anger, when the body releases a lot of adrenaline, temporary tunnel vision can occur. Usually, normal vision is restored without any treatment. Alcohol and drug use also affect peripheral vision.

Tunnel vision can be diagnosed with a visual field test, which is part of the routine eye examination protocol. The test examines the area of the retina where the peripheral image is visible and looks for blank spots in the field of vision.

You will be asked to look with one eye at a small light in the centre of the blank screen. The screen will flash briefly and you will be asked to simply press a button each time you see a flash. This checks every part of your retina to see how normal your peripheral vision is.