The cornea is the clear dome in front of the colored part of your eye. The cornea is normally round and acts like a lens to focus light into your eye.
Keratoconus is a progressive eye disease in which the normally round cornea thins and becomes misshapen, bulging into a cone-like shape. This cone shape distorts light as it enters the eye, causing blurred vision. However, unlike nearsightedness, farsightedness, or regular astigmatism, it is difficult to correct keratoconus with eyeglasses or soft contact lenses.
Keratoconus can occur in one or both eyes and often begins during a person’s teens or early 20s. It is more common among men, but can affect women as well.
Keratoconus Symptoms and Signs
As the cornea becomes more irregular in shape, it causes progressive nearsightedness and irregular astigmatism to develop, creating additional problems with distorted and blurred vision. Glare and light sensitivity also may occur.
What Causes Keratoconus?
New research suggests that an imbalance of enzymes within the cornea cause weakening of the corneal tissue which leads to keratoconus. This imbalance makes the cornea more susceptible to oxidative damage from free radicals, causing it to weaken and bulge into the cone shape.
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.
Keratoconus is also associated with overexposure to ultraviolet rays from the sun, excessive eye rubbing, a history of poorly fitted contact lenses and chronic eye irritation.
During the early or mild stages of keratoconus, eyeglasses or soft contact lenses may help. But as the disease progresses and the cornea thins and becomes increasingly more irregular in shape, glasses and soft contacts no longer provide adequate vision correction.
Treatments for moderate and advanced keratoconus include:
Gas permeable contact lenses
If eyeglasses or soft contact lenses cannot control keratoconus, then rigid gas permeable (RGP or GP) contact lenses are usually the preferred treatment. Their rigid lens material enables GP lenses to vault over the cornea, replacing its irregular shape with a smooth, uniform refracting surface to improve vision. But RGP contact lenses can be less comfortable to wear than soft contacts, the fitting RGP contacts for keratoconus can be time-consuming and require several visits.
Hybrid contact lenses
Hybrid contact lenses combine a rigid center with a soft peripheral border or “skirt.” They were designed specifically for keratoconus and vault above the eye’s cone shape for increased comfort. The manufacturer says hybrid contacts provide the crisp optics of a GP lens and wearing comfort similar to that of soft contact lenses.
A newer procedure to help flatten a keratoconic cornea call INTACS was pioneered in France, and is routinely being done by corneal specialists in the US. This procedure may be a good option for patients who are contact lens intolerant and who want to avoid a corneal transplant. INTACS involves the insertion of two arc-like plastic segments into the middle of the cornea to flatten it. A high-precision femtosecond laser is used to make the channels to insert the plastic segments.
Corneal cross-linking (CXL) is a non-invasive procedure used to strengthen corneal tissue which can slow or halt bulging of the cornea in keratoconus. With CXL, riboflavin (a type of B vitamin) is applied to the cornea, and then activated with UV light. Early results showing benefits of this method have been promising. Researchers have found that this simple treatment might significantly reduce the need for corneal transplants among keratoconus patients.
Some people with keratoconus reach the point where contact lenses or other therapies no longer provide acceptable vision. The cornea buldges so much that it becomes cloudy, a condition called hydrops. The last remedy to be considered may be a cornea transplant, also called a penetrating keratoplasty (PK). Even after a transplant, however, the patient still needs glasses or contact lenses for clear vision.
At Frontier Eye Care, we use the most advanced corneal topography technology to diagnose keratoconus. If we find that you have keratoconus, we will explain your condition and discuss the best treatment options with you. Call (307) 472-2020 to schedule an appointment.
For more information about keratoconus, visit The Keratoconus Center at www.keratoconus.com.