Keratoconus is a progressive eye disease in which the cornea thins and bulges into a cone-like shape, losing its roundness. The eventual cone shape deflects light which enters the eye towards the light-sensitive retina. The result is distorted vision.
Keratoconus can occur in one or both eyes. Keratoconus is relatively rare. If it does occur the onset usually begins in the teens or early twenties.
Symptoms of Keratoconus
Keratoconus may be difficult to detect and it typically develops slowly with few cases proceeding rapidly. As the cornea gradually becomes irregular in shape, progressively nearsightedness and irregular astigmatism increase. This creates problems such as distorted and blurry vision. Glare and light sensitivity as well. Keratoconic patients often need prescription changes every time they visit their eye doctor.
Causes of Keratoconus
The weakening of the corneal tissue which leads to keratoconus appears to be from an imbalance of enzymes in the cornea. The enzyme imbalance makes the cornea susceptible to oxidative damage from free radicals, causing weakness and corneal bulge.
Risk factors for this type of oxidative damage and weakening of the cornea include genetic predisposition, which explaining why keratoconus often affects multiple members of the same family. Keratoconus is also connected to ultraviolet (sun) overexposure, excessive eye rubbing, a history of poorly fit contact lenses along with chronic eye irritation.
For mild forms, eyeglasses or soft contact lenses help. As the severity of the disease progresses and the cornea thins and increasingly distorted shape, glasses or soft contacts will no longer provide adequate vision correction.
Treatments for moderate to advanced keratoconus include:
Gas permeable contact lenses. If eyeglasses or soft contact lenses cannot control keratoconus, then gas permeable (GP) contact lenses are usually the effective. Rigid materials enable the GP lenses to dome over the cornea, replacing the irregular shape with a smooth, uniform refracting surface thus improving vision.
There is a comfort cost though because GP contact lenses can be less comfortable to wear compared to soft lenses. Fitting of the contact lenses on keratoconic corneas are also challenging and more time-consuming. Expect frequent office visits for fine-tuning and fitting of the prescription, especially as the keratoconus continues to progress.