Eye Info

Hemianopsia: Stroke-related sight loss

Summary: Designed to help you understand more about your eye condition, this guide has been written by our experienced eye health team.

• What is Hemianopsia?
• What causes Hemianopsia?
• What are the effects of Hemianopsia?
• Can Hemianopsia be treated and will it improve?
• Is there a genetic component?
• Other sources of support
• What's next?

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What is Hemianopsia?

Hemianopsia, sometimes called Hemianopia, is blindness in one half of the visual field. This loss can be caused by a variety of medical conditions, of which stroke is among the most commonly experienced.

Hemianopsia is a functional defect which can affect the right or left side. Stroke patients with weakness of, for example, the right arm and leg have right sided poor vision. Some people lose sight mostly in the upper or lower part of the affected side, whereas others lose sight completely on all of the affected side.

Where the stroke has affected the right arm and leg, right sided vision can be affected.

What causes Hemianopsia?

Common causes of Hemianopsia are stroke, trauma (injury) or tumours. A stroke occurs when there is a sudden disturbance in the blood supply to the brain and in 75 per cent of cases this will be caused by a blocked blood vessel.

The other major cause of stroke is a leaking blood vessel. The majority of people who experience stroke will be over retirement age.

People with high blood pressure are at higher risk of stroke and heart-related illnesses. People with an abnormal heart rhythm may be at risk.

What are the effects of Hemianopsia?

Where there is identifiable change, Hemianopsia will affect both eyes and sight loss can be severe or so slight that many people do not notice the changes.

There are several types of field loss in this condition:

• Absolute: affected part of the retina is totally blind to light, form and colour.
• Relative: loss of form and colour but not of light.
• Congruous: identical defects in the visual fields of each eye
• Incongruous: both visual fields differently affected in one or more ways.
• Homonymous: nasal half of one eye and temporal (or outer) half of the other - this is typical of stroke patients
• Bitemporal: both temporal (outside edge) halves of visual field - this is typical of pituitary tumours

Can Hemianopsia be treated and will it improve?

There is unfortunately no specific treatment for the field of vision defect in stroke, though it may show improvement with time in some patients. It is however important to diagnose the condition in patients still driving to advise them and to treat any underlying problems eg abnormal blood pressure.

Is there a genetic component?

Although stroke is not itself a genetic illness, it may result from other health problems that exist within families and discussion with medical advisors will help to identify whether there might be genetic implications.

Other sources of support

1. The Stroke Association, serving England and Wales, offers information for individuals, their carers, professionals in the field and the general public and has a network of information centres countrywide. They can be contacted at

The Stroke Association
Stroke House
240 City Road
London EC1V 2PR
Telephone 0845 303 3100

2. Chest, Heart and Stroke Scotland offer health advice, general information and a 'listening ear'. They can be reached at

Chest, Heart and Stroke Scotland
65 North Castle Street
Edinburgh EH2 3LT
Telephone 0845 077 6000

3. The Stroke Information Centre serves North Wales and offers information on stroke services and support groups together with a range of services. They can be reached at

The Stroke Information Centre
HM Stanley Hospital
St Asaph
Wales LL30 2PT
Telephone 01745 58 23 68.

What's next?

Our Adapting to sight loss page gives information useful for people with a newly diagnosed sight problem.

If you need more information contact our Helpline on 0845 766 9999 / helpline@rnib.org.uk - calls are charged at local rates.

RNIB does not comment on every trend or development but, when a treatment becomes established / recognised, we revise our website material to include it.

Unfortunately, RNIB can only answer email enquiries from the UK. But you may find an organisation for people with poor sight in your country through our agencies database.

Back to eye conditions

Content author: eyehealth@rnib.org.uk

Last updated: 06/03/2008 15:41