Keratoconus

The cornea is the window of the eye. Light travels through the cornea past the lens to the retina and then the brain to form a visual image. The normal corneal surface is smooth and aspheric i.e. round in the center, flattening towards its outer edges. Light rays passing through it moves in an undistorted manner to the retina to project a clear image to the brain.

In patients with keratoconus the cornea is cone shaped (hence the name keratoconus, derived from the greek word for cornea (‘kerato’) and cone shaped (‘conus’). In patients with keratoconus the cornea is not only cone shaped but the surface is also irregular resulting in a distorted image being projected onto the brain.

Keratoconus

Because the cornea is irregular and cone shaped, glasses do not adequately correct the vision in patients with keratoconus since they cannot conform to the shape of the eye. Patients with keratoconus see best with rigid contact lenses since these lenses provide a clear surface in front of the cornea allowing the light rays to be projected clearly to the retina. Hence the vast majority of patients are treated with rigid contact lenses. There are however some excellent new surgical options for patients with keratoconus who cannot tolerate these lenses.

Many patients are initially unaware they have keratoconus and see their eye doctor because of increasing spectacle blur or progressive changes in their prescription. In many instances even a good refraction yields poor vision. Keratoconus is most often diagnosed by an eye specialist who may see typical findings when examining the patient at the slit-lamp. In early forms of the disease there may be no obvious finding on slit-lamp evaluation and the diagnosis is made by computerized topography only.

Keratoconus typically commences at puberty and progresses to the mid -thirties at which time progression slows and often stops. Between age 12 and 35 it can arrest or progress at any time and there is now way to predict how fast it will progress or if it will progress at all. In general, young patients with advanced disease are more likely to progress to the point where they may ultimately require some form of surgical intervention.

Keratoconus may occur in one eye only initially but most commonly affects both eyes with one eye being more severely affected than the other. Both males and females are equally affected.

Causes of the disease may be attributed to

  • Genetic factors
  • Excessive rubbing of the eyes
  • Deficient collagen crosslinking caused by free radicals

Treatment options

 

  • Corneal collagen cross linking
  • Corneal transplant
  • Intacs to improve visual outcome