While the causes of keratoconus are not fully understood there are some patterns that can be observed in patients with keratoconus.
One cause of keratoconus this is under investigation is genes as there might be some genetic basis to keratoconus. It is not atypical to find several patients with keratoconus within the same extended family. This genetic link is certainly not an autosomal dominant trait since the chance of related members of a family having keratoconus is certainly less than 1 in 10.
Another possible cause of keratoconus is an allergic disorder. Allergy and atopic disorders include problems such as hay fever, eczema, asthma, and food allergies. People suffering from these problems show a higher percentage of keratoconus than the general population. While this does not indicate causation, it does show correlation.
Down Syndrome can also be shown to be correlated with keratoconus. Again, this does not mean that Down Syndrome is a cause of keratoconus but it does show that the two disorders are correlated.
Some studies have indicated that eye rubbing might be a cause of keratoconus. Vigorous rubbing has been a common clinical observation among patients with keratoconus. It has been suggested that rubbing can weaken collagen links that are already weak in patients with keratoconus. Excessive rubbing could also lead to inflammation and immune system reactions with the corneal tissue. While eye rubbing has not been established as a cause of keratoconus, it does show strong indications of correlation.
Hormones have also been indicated as a possible cause of keratoconus. Patients tend to develop keratoconus in the teenage years. Women are also noted to begin showing signs of keratoconus during or after pregnancy. Both of these periods are marked by increased hormonal production.
While rigid contact lenses are often a treatment for keratoconus, there are some studies that indicate that they could also be a cause of keratoconus. Several studies noted onset of keratoconus following fitting of rigid contact lenses. It has been suggested that the contact lens rubs against the cornea and causes a weakening of the collagen linking with the cornea tissue. Others have suggested that since patients with keratoconus are generally near-sighted, they naturally tend to gravitate towards treatment with contact lenses.
The official cause of keratoconus is still unknown.