The cornea is the clear transparent window at the front of the eye which is usually an even round shape. Keratoconus is a condition which causes the cornea to become thinner and bulge outwards, forming a cone-like shape. It is a condition that slowly gets worse over time but how quickly and how severely it progresses varies from person to person.
The cause of keratoconus is unknown, it tends to occur more in people who suffer from asthma, eczema and other allergic conditions. It’s not generally thought to be a genetic condition but occasionally more than one person in a family may be affected. Patients with Down Syndrome and certain connective tissue diseases are at higher risk of developing keratoconus.
Who can get keratoconus?
Keratoconus is usually diagnosed in young people at puberty, in their late teens or early twenties. It is more common in non-Caucasians and depending on ethnicity, affects up to 1 in 450 people.
How keratoconus affects your vision
Vision is often not affected in the early stages although it can be detected by your local optometrist. As the condition progresses it causes blurred vision because the front of the eye is no longer smooth and round, resulting in short sightedness and irregular astigmatism. In advanced stages, the further changes in shape and thinning of the cornea can cause scarring and loss of transparency which makes the vision blurred by reducing the amount of light that enters the eye.
How is keratoconus diagnosed?
An eye doctor (ophthalmologist) will examine the eyes with a microscope called a slit lamp; they may also do a corneal topography scan which assesses the shape and thickness of the cornea in detail.
How is keratoconus treated?
There is no cure for keratoconus, in the early stages patients may just need glasses to see well, eventually contact lenses may need to be fitted for better vision. The contact lenses are usually small hard lenses (rigid gas permeable), some are soft lenses and some are special lenses made specifically for keratoconus eyes. Contact lenses do not make keratoconus better or worse, they just give better vision. In very advanced cases where there is significant scarring or contact lenses fail to improve vision, a corneal transplant may be needed.
Corneal collagen cross-linking is a new treatment that can stop keratoconus getting worse, this uses ultraviolet light and vitamin B2 (riboflavin) drops to stiffen and strengthen the cornea. It is only suitable where the corneal shape is continuing to change, beyond a certain point the cornea may become too thin and it would not be safe to perform the procedure. For patients in their late 30s the cornea naturally becomes stiffer, so collagen cross-linking is generally not required, below this age the cornea is more flexible and progression of the condition is more likely.