KERATOCONUS  (cone shaped cornea)

What is keratoconus?
Keratoconus is a common bilateral corneal condition, occurring in more than 1 in 1000 people. The condition typically starts in adolescence and early adulthood.

Keratoconus is a disease with an uncertain cause, and its progression following diagnosis is unpredictable. If afflicting both eyes, the deterioration in vision can affect the patient's ability to drive a car or read normal print. Further progression of the disease may lead to a need for surgery.

Despite its uncertainties, keratoconus can be successfully managed with a variety of clinical and surgical techniques, and often with little or no impairment to the patient's quality of life.

Keratoconus (from Greek: kerato- horn, cornea; and konos cone)

The cornea is the clear window on the front of the eye. It is usually a regular spherical dome in shape. The substance of the cornea consists of hundreds of layers that are linked to each other by a substance called collagen. If these collagen cross-links between layers are lost due to keratoconus, there is a progressive corneal thinning and stretching which gradually progresses, often in both eyes. Normal pressure within the eye causes the cornea to bulge forward into an irregular cone shape. When light enters the eye, it first passes through the cornea. If the cornea has turned conical, there is distortion of the image. The eye develops astigmatism (cylindrical errors) and myopia [shortsightedness] and the vision may become severely blurred.

A simulation of the multiple images seen by a person with keratoconus
 
RISK FACTORS

Reported risk factors for keratoconus include eye rubbing, a family history of keratoconus, genetic predisposition, certain systemic disorders such as Down's syndrome, ocular allergy, connective tissue disease, and long-term rigid contact lens wear. It is usually an inherited corneal disorder, often in an autosomal dominant fashion. This means that approximately 50% of family members may end up with it. But it also can be random with no other family members affected. It affects men and women in equal proportions and is bilateral in 90% of patients.