What Is Keratoconus?
Keratoconus is a progressive eye disease that usually occurs in adolescents or early third decades of life, in which the normally round cornea thins and begins to bulge in to a cone-like shape. This cone shape deflects light as it enters the eye on its way to the light-sensitive retina, causing distorted vision. Keratoconus may occur in one or both eyes, but in 90% of cases it is seen in both eyes.
Signs and Symptoms of Keratoconus
Diagnosis of keratoconus may be difficult due to its slow progress. Keratoconus causes progressive nearsightedness and irregular astigmatism to develop, creating additional problems with distorted and blurred vision. Glare and light sensitivity also may occur. Often, keratoconic patients experience changes in their eyeglass prescription every time they visit their ophthalmologists.
The cause of keratoconus is unknown. This disease can be a genetic eye disorder because keratoconus often affects more than one member of the same family.
In the mildest form 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 regular soft contact lens designs no longer provide adequate vision correction.
The next treatment of keratoconus is the use of rigid gas permeable contact lenses. These lenses are more capable of correcting irregular astigmatism due to keratoconus.
Fitting contact lenses on a keratoconic cornea is challenging and time-consuming. That is why frequent referrals and visits for fitting the lens and changing eyeglasses prescription are unavoidable for keratokonic patients. This process needs to be repeated; especially if keratoconus continues to progress and keratoconic patients' eyeglasses prescriptions should be changed every time they visit their ophthalmologists.
Some people with keratoconus can't tolerate a rigid contact lens, or they reach the point where contact lenses or other therapies no longer provide acceptable vision, in this situation the next treatment to be considered may be a cornea transplant, also called a penetrating keratoplasty.
Currently, newer methods such as inserting intracorneal rings such as Intacs and Ferrara are used for the keratokonic patients who are not able to tolerate hard lenses and also corneal transplantation due to its complications is not recommended for them. A study on this method has been ongoing in recent years and the results indicate a relative improvement in keratoconic patients' vision, although it has not been shown that this method inhibits the progression of the disease.
Keratoconus and Refractive Surgery
Performing any laser refractive surgery such as LASIK and PRK in patients with keratoconus due to the progressive corneal thinning is not possible.