Keratoconus is an eye disorder where the cornea (the transparent layer of the eye that covers the pupil and iris) becomes thin and changes from being dome-shaped to cone-shaped, resulting in distorted vision.
Keratoconus most often affects people aged between 10 and 25 years of age, and usually affects both eyes.
Symptoms usually progress slowly and include:
- blurred or distorted vision;
- eyesight that is worsening and requiring many changes in prescription for glasses or contact lenses; and
- sensitivity to light and glare.
The exact cause of keratoconus is not known. However, there are some factors that may be associated with an increased risk of keratoconus, including:
- repeated vigorous eye rubbing;
- atopy â€“ an inherited tendency to develop certain allergic conditions (such as hay fever, allergic conjunctivitis, eczema and asthma);
- certain inherited or genetic disorders (including Down syndrome); and
- a family history of keratoconus.
Diagnosis and tests
An ophthalmologist (eye doctor) can diagnose keratoconus by examining your eyes and performing vision tests. A slit lamp examination (where your doctor uses a special instrument to view the eyes) can help determine the shape of your cornea.
Imaging of the eyes can also help in the diagnosis of keratoconus. Computerised corneal mapping using so-called optical scanning techniques can take images of the cornea and measure its thickness and shape.
Treatment for keratoconus depends on how severe it is and how quickly the disease is progressing.
Blurred vision associated with mild to moderate keratoconus can be treated with eye glasses or contact lenses. For keratoconus that is getting progressively worse, rigid contact lenses are often preferred because they can be used to stabilise the shape of the cornea as well as improve vision.
There are several other specialised types of contact lenses that can also be used in the treatment of keratoconus.
Surgery may be required to treat people with severe keratoconus and those who cannot tolerate wearing contact lenses.
One option is the insertion of plastic intracorneal ring segments, which can help improve the shape of the cornea, slow progression of the disease and improve vision.
In severe cases, corneal transplants (also known as keratoplasty) may be needed to treat keratoconus.
Corneal collagen cross-linking
A new treatment for keratoconus is emerging, called corneal collagen cross-linking. In this treatment, riboflavin (vitamin B2) eye drops are applied to the cornea, followed by exposure to ultraviolet A (UVA) light. This treatment aims to strengthen and stiffen the cornea and stop (or slow) progression of the disease.
Trials for this potential new treatment are still ongoing, and this type of treatment is not suitable for everyone.