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Keratoconus

Also known as: Corneal ectasia

Background

Keratoconus is a progressive eye condition where the cornea (front surface of the eyeball) becomes thinned and the area then becomes conical or cone-shaped. It usually occurs asymmetrically in both eyes. The incidence is around 1 in 3,000 to 1 in 10,000 depending on ethnic groups and where in the world people live. 

Keratoconus rarely appears in an individual until puberty. Although it is uncertain how far keratoconus will develop, the condition is most unlikely to cause blindness. With the current treatment available, most people with the condition should be able to lead a normal life.

Credits

Updated November 2017 by Ms L Speedwell, Head of Optometry, Great Ormond Street Hospital and Principal Optometrist, Moorfields Eye Hospital, London, UK.

Although great care has been taken in the compilation and preparation of all entries to ensure accuracy, we cannot accept responsibility for any errors or omissions. Any medical information provided is for education/information purposes and is not designed to replace medical advice by a qualified medical professional.

What are the symptoms?

Reduced clarity of vision: An eye test will reveal increased astigmatism (spectacle prescription needed when the eye is more rugby ball shaped rather than spherical). The vision worsens as the astigmatism becomes more irregular and spectacles become less effective.

What are the causes?

The cornea becomes stretched and thin near its centre and bulges resulting in increased short-sight, astigmatism and distorted vision.

Keratoconus is often associated with atopic conditions (asthma, eczema, hayfever) and can be made worse if the eyes are itchy and rubbed a lot. It can be associated with other conditions, such as Down's syndrome or it can have a genetic cause and affect other members of the family.

How is it diagnosed?

It is diagnosed using a slit lamp (special microscope) and with corneal topography (surface mapping) which shows the irregular corneal contour.

How is it treated?

People with early or mild keratoconus can often manage with spectacles or soft contact lenses but if it is more advanced, rigid contact lenses are the usual treatment to improve the vision.  Contact lenses do not slow down the rate of progression but they provide good vision while being worn.
If the eyes are itchy, eye rubbing should be avoided and if necessary, treatment such as anti-allergy eye drops or medication should be used.

Corneal cross linking (CXL) is treatment for eyes with relatively early keratoconus that is found to be deteriorating.  The cornea is treated with riboflavin eye drops and ultraviolet light in order to strengthen it and slow down or even halt the changes.  CXL is not suitable for everyone and it may not prevent keratoconus from progressing.

In a small percentage of cases, where keratoconus is advanced and contact lenses are either not tolerated or do not improve the vision sufficiently, the cornea may need to be replaced surgically with a corneal transplant or graft. Contact lenses are frequently needed after a corneal transplant to achieve good vision.

Inheritance patterns and prenatal diagnosis

Inheritance patterns
Most cases of keratoconus are sporadic but some are known to be familial.

Prenatal diagnosis
Not applicable.

Is there support?

Keratoconus Self Help and Support Group

Tel: 020 8993 4759
Email: chair@keratoconus-group.org.uk
www.keratoconus-group.org.uk

A Registered Charity in England and Wales No. 1057629. It provides information and support for people with Keratoconus in the UK. The Group organises regular meetings for members, holds a bi-annual conference, raises money for research and works to raise awareness of the condition.

Group details last updated November 2017.

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