What is keratoconus?
The word “keratoconus” comes from the Greek words “kerato”, which means cornea and “konos,” which means cone. Though the disorder was identified two hundred years ago, it was not well distinguished from other known eye problems until 1864. Keratoconus refers to the progression of a conical shape to the cornea. The characteristically round smooth shape of the cornea bulges in the center due to thinning of the tissue. The corneal tissue can become as thin as half of its original thickness.
Signs & Symptoms
With keratoconus, the uniform transparent corneal surface becomes distorted causing increased astigmatism, decreased vision and sometimes scarring. These symptoms typically occur in both eyes, however, one eye may be affected more severely.
Who has Keratoconus?
Keratoconus most commonly begins in the teens around the onset of puberty or in the twenties. One out of 2,000 people in the general population have been reported to have keratoconus. Roughly one out of every 10 patients with keratoconus has family members with the disease as well. The condition has not been associated with any particular social, cultural or geographical background.
Unfortunately, we do not know what causes keratoconus. A genetic basis has been speculated due to a higher familial pattern of occurrence than the general population. Some physicians are exploring the possibility of endocrine involvement since the disease often occurs with puberty. Keratoconus may also be associated with other disorders such as eczema. It is possible that rubbing the eyes contributes to the disease as well. One of the latest research efforts explores the relationship of keratoconus with the activity of certain enzymes in the eye. Although the causes of keratoconus may not be known, treatments for it are available.
Glasses and contact lenses may be effective treatment for the early stages of Keratoconus. As the condition progresses, contact lenses generally are more effective than glasses. Usually gas permeable lenses are used, but this depends upon the patient. Fitting contact lenses in Keratoconus patients can be difficult because so many trials are often necessary. In some cases, contact lenses may need to be custom made. The lenses may feel uncomfortable (especially at first) or they may have a tendency to fall out of the eyes. However, 90% of the time successful lenses can be fitted.
About 10% of the time, corneal transplant surgery becomes necessary. Corneal transplants for Keratoconus patients may be full-thickness (PK – Penetrating Keratoplasty) or partial-thickness (DALK – Deep Anterior Lamellar Keratoplasty).This surgical procedure has about a 95% success rate in Keratoconus patients. Like any surgical procedure, corneal transplant surgery has certain risks involved.
Collagen Cross Linking
Our practice is now involved in collagen cross linking studies. Collagen cross linking is a new procedure that is becoming available in the United States through IRB approved research trials. Keratoconus and ectasia are conditions in which the cornea is weakened and thinning, which can result in bulging. The protruding shape can distort vision and lead to corneal scarring. Collagen cross linking is a normal part of the aging process that helps to strengthen adjacent collagen fibers in the cornea. The collagen cross linking treatment helps to accelerate this process in corneas weakened by disease. The proposed treatment was first described in 1992 and has since undergone multi-center trials to be submitted to the Food and Drug Administration in order to be approved for use in the United States. Though the procedure has not yet been approved by the FDA, it is being widely used throughout Europe and Canada.
When a patient is entered into the study, we will first remove the front layer of the cornea (the epithelium). The patient will then receive riboflavin (vitamin B2) eye drops every two minutes for thirty minutes. During this treatment a UV light is shined on the eye for thirty minutes. The patient will receive regular follow-ups to compare their visual acuity and progression pre- and post-treatment. For many patients this procedure may delay or prevent the need for a corneal transplant.
Collagen cross linking can also be used in select cases of corneal infection that are not responsive to conventional medications.
We welcome you to make an appointment for further discussion on your specific treatment options.