Keratoconus

What is keratoconus?

Keratoconus is an eye disorder in which the corneal tissue thins and deforms. The cornea is unable to support the internal eye pressure and it bulges out in a cone shape, hence the name, kerato, which means cornea, and conus, which means cone shaped in Latin. 

It is a degenerative condition of the cornea that appears progressively in one or both eyes.    

Disease prognosis

Although keratoconus is a degenerative disease, it can be corrected with glasses, with contact lenses, and different surgical procedures.   

A patient with keratoconus should have regular corneal topographies to detect changes in the cornea.

What are the symptoms of keratoconus?

Keratoconus usually affects young people in the form of myopia and astigmatism as well as blurred vision. It may also cause eye irritation and increased photophobia (light sensitivity). A specialist will confirm the disease when and if they detect corneal thinning in the central or paracentral part of the cornea.

Tests for keratoconus

A corneal topography is done to check the curvature of the front and the back of the cornea and to detect areas of corneal thinning. New methods also measure the thickness of the very superficial layer of the cornea that is called the epithelium, as it starts to have different behaviour in keratoconus patients. 

What causes it?

Keratoconus was thought to be a pure degenerative disease, however, new evidence indicates the disease to be part of an inflammatory condition, with intracorneal inflammatory cells causing focal thinning and protrusion of the cornea. This is evident as the disease is more common in patients with a history of allergic conditions such as atopic dermatitis and asthma. Bad habits associated with allergic conditions, like eye rubbing, are known risk factors. Genetics may also play a role, as the disease is more common in some genetic conditions such as Down's syndrome.     

How can it be prevented?

To prevent keratoconus, it is recommended that you have your eyes checked at least once a year. There are also some actions that are best avoided, such as continuously rubbing your eyes. Early detection is crucial to be able to treat the symptoms and prevent corneal degeneration.

What is the treatment?       

Prevention is the first thing to consider, especially if the patient feels that their glasses prescription is changing in a short period of time, as mild cases could be managed with glasses and contact lenses.

If the ophthalmologist discovers the keratoconus in an early stage, it could be controlled with collagen cross linking, which involved stiffening the cornea with ultraviolet light and vitamin B (Riboflavin).

In more advanced cases in which the patient cannot tolerate contact lenses, and if the vision is not corrected enough with glasses or contact lenses, a new procedure involving implanting rings inside the cornea (CAIRS surgery). The rings are made from a donor cornea, which makes them safer than the plastic rings that were previously used to correct the keratoconus corneas.

A new procedure to add tissue to severe cases of keratoconus to increase the corneal thickness and to flatten the cornea has been introduced in a few centres around the world. 

Eventually a partial thickness corneal graft can be considered in severe cases to restore the clarity of the cornea.

What specialist should I see?  

Keratoconus should be managed by an ophthalmologist.