Eye Info

Best's Disease

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

• What is Best's Disease
• Causes of Best's disease
• Risk groups and factors
• Effects of Best's Disease
• Treatment
• Prognosis
• Genetic implications
• Other sources of support
• What's next?

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What is Best's Disease

Best's disease, also known as Best's vitelliform macular dystrophy, is an hereditary form of progressive macular dystrophy first identified in 1905.

The macula is a small area of about 1mm in diameter in the centre of the retina, at the back of the eye where there is a concentration of cone cells. These cells are responsible for colour vision, sharp visual acuity and central vision. There are 6-7 million cone cells in the retina, the highest concentration of which is in the fovea, a tiny area in the centre of the macula.

The condition can be identified between 3 and 15 years of age.

Causes of Best's disease

Best's vitelliform macular dystrophy is a condition that tends to run in families and its cause lies within individual genetic make-up.

Risk groups and factors

The condition tends to occur in families with a history of Best's.

Effects of Best's Disease

Sight loss can be variable but, like other macular problems, Best's disease threatens central vision in one or both eyes.

Electroretinogram tests, which assess the electrical response of the retina when stimulated by light, can be used to identify people with the problem.

Within 5 identifiable stages, examination of the eye discloses a distinct progression. At first and second stages, there may be little or no effect on sight.

Initially a recording of eye movements and eye position identifies abnormal electrical potential. Eyes will be tested resting or moving in dark and light conditions.

At the second stage (usually between 10-25 years of age), typical yellow spots, sometimes accompanied by material leaking into a space by the retina, can be observed; an observation called "egg-yolk" lesion.

When part of the lesion becomes absorbed this is identified as stage three. Even at this stage there may be little affect on vision.

At the fourth stage, when the "egg-yolk" breaks up, in a process referred to as "scrambled-egg", sight will probably be affected.

The fifth and final stage is when the condition causes the most severe sight loss.

Treatment

RNIB is not aware of any current effective treatment, but scientific research, both traditional and genetic, may provide useful treatments for the future.

Prognosis

In many people serious sight loss is avoided but others can lose sight which may approach levels which would qualify for registration as sight impaired (partially sighted).

Genetic implications

Best's is autosomal dominant. With such genetic conditions it is likely that there would be several affected individuals in successive generations but Best's can be erratic and may miss a generation.

Further information and counselling will be available from a specialist clinic and your GP will be able to advise you about local Genetic Services.

Other sources of support

1. Low Vision Services

Low Vision Services exist to optimise vision by the use of techniques, aids, lighting and general information. The eye specialist will be able to advise you on the nearest Low Vision Clinic within the Hospital Eye Service offering an equipment loan service.

2. Although there is no support group specialist to Best's disease, the

Macular Disease Society
Darwin House
13a Bridge Street
Andover
Hampshire
SP10 1BE
Telephone 0845 241 2041

will be able to offer more information and advice on this condition and all conditions affecting the macula.

3. The Partially Sighted Society
7 - 9 Bennetthorpe
Doncaster
South Yorkshire
DN2 6AA
Telelephone 0844 477 4966
Fax 0844 477 4969

will be able to advise on Low Vision Services, lighting and aids.

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 or 020 7388 2525 / 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.

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Content author: eyehealth@rnib.org.uk

Last updated: 06/03/2008 15:41