Causes of Keratoconus
There are no definite keratoconus causes but there are different risk factors which can increase the incidence of it. These factors can be genetic, environmental and cellular factors.
These factors will cause changes in the enzymatic environment of the cornea in which there will be imbalance between several corneal enzymes that protect the cornea from free radicals and oxidation process.
Corneal enzymes that protect the cornea from these free radicals are catalase and superoxide dismutase. These free radicals will damage the cornea through weaken of links between collage fibers.
Risk Factors of keratoconus
1- Family history: Its incidence will increase when there is a family history of keratoconus. The genes that are responsible for this are not well identified.
2- Down syndrome: there are a correlation between down syndrome and keratoconus but the exact link or gene have not been identified.
3- Allergic disorders: which can be either localized eye disorders like allergic conjunctivitis or generalized allergic diseases like asthma, atopy, eczema and food allergic.
4- Chronic eye rubbing. With continuous chronic rubbing, there will be weakening of corneal collage which will predispose the eye to keratoconus.
5- Ultraviolet sunlight exposure.
6- Chronic eye irritation which can induce inflammation inside the cornea can further weaken the enzymes and generate more free radicals.
7- Poor fitted contact lens which also can induce intense inflammation.
8- Hormonal changes during puberty and during pregnancy can cause alteration in immune system and enzymes.
9- Iatrogenic keratoconus. In which keratoconus can occur after refractive surgery like lasik. Because of this cause, corneal thickness should be measured before lasik surgery to eliminate patients with thin cornea.