Keratoconus (from Greek: kerato- horn, cornea; and konos cone), is a degenerative disorder of the eye in which structural changes within the cornea cause it to thin and change to a more conical shape than its normal gradual curve.
New research suggests the weakening of the corneal tissue that leads to keratoconus may be due to an imbalance of enzymes within the cornea. This imbalance makes the cornea more susceptible to oxidative damage from compounds called free radicals, causing it to weaken and bulge forward. Risk factors for oxidative damage and weakening of the cornea include a genetic predisposition, explaining why keratoconus often affects more than one member of the same family. The exact cause of keratoconus is uncertain, but has been associated with detrimental enzyme activity within the cornea. A genetic link seems likely, as the incidence rate is greater if a family member has been diagnosed.
Keratoconus also is associated with overexposure to ultraviolet rays from the sun, excessive eye rubbing, a history of poorly fitted contact lenses and chronic eye irritation from allergies. Other research suggests a hormonal link may exist.
Keratoconus can cause severe distortion of vision, with multiple images (ghosting), streaking and sensitivity to light (halos). It is often diagnosed in the patient’s teenage years and gets worse in the twenties and thirties. As keratoconus is bilateral in 95% of cases, afflicting both eyes, the deterioration in vision can affect the patient’s ability to drive or read normal print, operate machinery, computers and so on. In most cases, corrective contact lenses are effective enough to allow the patient to continue to drive legally and likewise function normally, which includes continuing to work, play sports and live a normal life.
Further progression of the disease may require surgery including intrastromal corneal ring segments (Intacs, ferrara rings), corneal collagen cross-linking (CXL, C3R) or corneal transplantation/ corneal graft. However, despite the disease’s unpredictable course, keratoconus can often be successfully managed with little or no impairment to the patient’s quality of life.
Keratoconus affects around one person in two thousand, and 1 in 500 of the black and Asian communities, people with Down’s Syndrome often have keratoconus.