Keratoconus
Recent estimates indicate that 1 in 2000 Americans will develop keratoconus (KC). What is it, who will develop the condition, and how is it treated?
Basics –
The cornea is the clear portion on the front of the eye that covers the pupil and the iris. Some compare it to the windshield of a car. The smooth, transparent surface and rounded shape are essential for normal function. If the shape or clarity of the cornea is abnormal, vision can be affected.
Details –
Normal Eye
(Fig.1)
In a patient with keratoconus, the cornea is considerably thinner. The result is a cornea with a bulge, appearing much like a cone or football. (See Fig. 1)
The exact cause of the thinning remains under investigation but recent studies indicate that it may be due to an imbalance of the enzymes within the cornea. Some researchers believe that the endocrine system is in some way a contributing factor – primarily because keratoconus is often diagnosed during puberty, during the early to late teen years. Keratoconus has been diagnosed in middle-aged patients as well and does not appear to be gender or race specific. Most doctors agree that eye rubbing is very commonly associated with the worsening of keratoconus and advise patients to seek treatment for seasonal allergies in an effort to avoid the need to rub the eyes.
Treatment options –
KC patients experience significant visual distortion and blurring. Early on, glasses and soft contact lenses will help with the rapidly changing vision. As the condition progresses, rigid, gas permeable contact lenses become the treatment of choice. The rigid lenses help to create an artificially smooth, rounded surface of the eye, improving vision. Sometimes, soft lenses are used under the rigid lenses (“piggybacking”) to improve comfort for the patient. Fitting contacts can be a tedious process for the patient with keratoconus, and requires the skill and knowledge of a doctor experienced in keratoconic contact lens fittings. Frequent visits to adjust the fit and prescription are not uncommon. While contact lenses improve the quality of vision for these patients, they do not stop the progression of the condition.
Over time, approximately 20% of patients with keratoconus become severe enough to require corneal transplant surgery. During this outpatient procedure, the center of the cornea is removed and replaced with a section of donor cornea. While surgery corrects the bulge in the corneal surface, most patients will require glasses or contact lenses for the best possible vision following treatment.