What is keratoconus?
The cornea is a protective clear window at the front of your eye - a transparent dome that covers the coloured iris and also helps to focus light on the retina at the back of the eye. Theoretically the cornea should be perfectly spherical, like a halved tennis ball, but more often than not the cornea is more oval, like a teaspoon.
When the cornea is more teaspoon shaped, it distorts images (just like looking at your reflection in the back of a teaspoon) and this is called ‘astigmatism’. Sometimes this irregular shape to the cornea can be extreme, and the cornea actually becomes cone-shaped - this is called keratoconus.
Keratoconus makes your vision very blurred and distorted and will result in the astigmatism correction in your prescription (the cylinder or cyl part) being quite high. A common symptom is seeing multiple images with one eye.
Who gets keratoconus?
Keratoconus typically starts during the teens, although not in every case. It is often associated with a history of allergies (hay fever, asthma, eczema). Down’s syndrome and Marfan’s syndrome are also linked with it.
It is difficult to pin the condition down to a specific cause, and even something as seemingly harmless as excessive eye rubbing has been linked with causing/exacerbating the condition. Importantly though it isn’t contagious.
Can spectacles or contact lenses help?
In the early stages, yes. Glasses help when the degree of astigmatism is still relatively low. As the condition progresses the spectacles will become less and less effective, so the next step is conventional contact lenses, particularly hard contact lenses. These lenses ‘float’ on the tears of the eye and so are effective at correcting vision, even well into the advanced stages of the condition. This is firstly done with conventional hard contact lenses, though there are special keratoconus hard lenses (and now even soft keratoconus contact lenses).
Is there any surgery available?
At it’s most severe, there are numerous surgical interventions which can help and this isn’t always with a complete corneal graft (transplant). A common method now is called ‘collagen cross-linking’ and this works in a similar manner to laser eye surgery. UV light is used to strengthen the collagen within the cornea and has been extremely effective in halting the condition’s progress. Collagen cross-linking is available in some regions on the NHS, but remains a private procedure in others. Our associates Advanced Vision Care offer treatments, www.advancedvisioncare.co.uk
Does the condition keep getting worse?
Not always. Keratoconus is a ‘self-limiting’ condition and can burn itself out at any stage. Some people are left with mild astigmatism that never worsens; others can be left with moderate to high astigmatism correctable with hard contact lenses, never requiring surgical treatment.