Keratoconus
Keratoconus is an eye disease in which the cornea, the front part of the eyeball, becomes thinner and bulges forward becoming cone shaped. The disease is considered to be progressive. The cone shaped irregular area of the cornea distorts light as it enters the eye causing vision to be blurred. Keratoconus can be in either one or in both eyes. It typically is first observed in the teens or early twenties.
In the early stages of keratoconus it is possible to correct the condition with eyeglasses or traditional soft contact lenses. This is because the cornea does not become extremely distorted until later in the condition. It is common for keratoconus to be missed in the early stages of the disease. As the vision becomes more distorted, eventually a stage is reached in which normal eyeglasses and soft contact lenses will not provide adequate vision. There are, however, good treatment options available to treat the condition. These options include rigid gas permeable contact lenses, special “hybrid” contact lenses that are made from a combination of polymers in which the center part is rigid and the periphery is soft, and combinations of rigid gas permeable contact lenses over various types of soft contact lenses (called “piggybacking”).
There are also now available some new custom soft contact lenses that have a unique shape that make it possible to mask a great deal of the distortion found on the cornea. While these new lenses do not work for all cases, they have been shown to be much better than traditional soft lenses and offer a significant improvement in vision that will satisfy many keratoconus patients. In many cases, it is important for the portion of the lens that sits over the distorted cornea to be of a rigid material or in the case of soft contact lenses to be of sufficient thickness to mask the irregularity of the cornea. In effect, the new front surface covers up the irregular distorted part of the cornea creating a new smoother and less distorted surface. This causes the irregularity to be compensated for and the patient can then enjoy much more normal and clearer vision.
It is believed that there is a genetic predisposition for keratoconus. Research indicates that the cornea becomes weakened due to an imbalance of enzymes within the cornea. The condition is also associated with allergies, excessive eye rubbing, and a long term history of poorly fitting contact lenses.
Other treatment options in addition to rigid gas permeable contact lens designs include corneal collagen cross linking (C3-R), “Intacs” and corneal transplant surgery. Corneal collagen cross linking involves subjecting the cornea to an application of riboflavin (vitamin B2) eyedrops for a short period of time followed by exposure to ultraviolet light. This procedure has been shown to strengthen the collagen fibers in the cornea and to help reduce the tendency for the cornea to bulge. “Intacs” are plastic half rings that are inserted into the cornea to help stabilize the surface and provide a better platform for the application of contact lenses. In addition, correctable vision can improve after the insertion of “Intacs”. Corneal transplant surgery is done only when the cornea is so pointed that it is difficult to get a contact lens to be supported upon it or when there is significant corneal scarring causing a drop off in correctable vision. A new donor cornea is inserted into the area of the cornea where the bulge is. This procedure is improving due to new surgical techniques.
If a patient is considering contact lenses to correct keratoconus, it is very important to make sure that the contact lens fitter be well versed in the various treatment options. The contact lens fitter should have several fitting sets so that various options can be tried. Fitting keratoconus takes time and patience. The patient needs to be able to come back for the necessary follow up visits until a final solution is realized. Contact lenses for keratoconus are considered to be “medically necessary” by most insurance plans and vision plans. The fitting of the lenses and the time involved on the part of the fitter are very costly, but the cost can be partially or completely offset by the insurance plan’s contribution to process.
If you have any questions about keratoconus, please call the office to schedule a consultation.