There are many theories on what might lead someone to get keratoconus, but the exact cause of the eye disease is unknown. Based on research and its association with other conditions, doctors and researchers have come up with some theories. However, no one theory explains it all and some say it may be caused by a combination of factors.
It is believed that genetics and the environment both play a role in keratoconus.
- Eye Rubbing: People with keratoconus can damage their corneas more easily with minor trauma such as eye rubbing.
- Many conditions associated with vigorous eye rubbing due to itching can cause keratoconus. These include seasonal allergic conjunctivitis, contact lens associated irritation/allergy and various atopic diseases (such as hay fever, eczema, asthma and food allergies).
- Oxidative Stress: Some research indicates an abnormal processing of the superoxide radicals in the keratoconic cornea and an involvement of oxidative stress in the development of this disease. This means keratoconic corneas lack the ability to self-repair routine damage easily repaired by normal corneas. Like any tissues in the body, the cornea creates harmful byproducts of cell metabolism called free radicals. The keratoconic corneas are not able to eliminate the free radicals so they stay in the tissue and can cause structural damage.
One theory is that keratoconus could be caused by genetics. However, based on current scientific information there is less than a one in ten chance that a blood relative of a keratoconic patient will have keratoconus. So the majority of patients with keratoconus do not have other family members with the disease.
Some studies support that the cause of keratoconus could be developmental in nature, showing that keratoconic corneas lack important anchoring fibrils that structurally stabilize the anterior cornea. This causes the cornea to bulge due to the increased flexibility.
Many genetic diseases are associated with keratoconus, including Trisomy 21 (Down's Syndrome), Marfan's Syndrome, Ehlers-Danlos Syndrome.
Keratoconus typically starts in adolescence and progresses until early adulthood. One theory for why the progression of keratoconus stops in early adulthood is that the UV exposure and natural aging of the cornea results in collagen crosslinking of the cornea. This in turn increases the rigidity of the cornea and prevents progression. Corneal collagen crosslinking (CXL) is a procedure that accelerates this natural process, thereby halting the progression of keratoconus in most cases. For more information about CXL, please visit this page.