The cornea is the clear dome on the front of the eye. The normal corneal surface is smooth and relatively round in the center, like a basketball. The light rays pass through a normal cornea in an undistorted manner to project a clear image on to the retina, which is like the film in a camera, the image is then sent to the brain. Keratoconus is a disease of the collagen that produces thinning and distortion of the corneal tissue. As the tissue thins, the normal pressure within the eye causes the tissue to slowly bulge forward into a cone-like shape, and as the disease progresses, the surface becomes irregular, distorting the images that are projected on to the retina.
Most patients with keratoconus initially see their eye doctor because of increasing blurriness with their glasses, or difficulty wearing their contact lenses comfortably. It typically begins in the teen years and progresses in to the 30s or 40s. There is no way to predict how fast it will progress at all. Keratoconus will typically appear in both eyes, with one usually being more severely affected than the other, although there have been some cases when only one eye is affected. The cause of keratoconus is still unknown, although there is evidence that supports a genetic origin, which can be exacerbated by environmental factors.
Patients with mild cases of keratoconus can comfortably wear glasses or soft contact lenses however if keratoconus is more severe these options will not give the patient adequate correction. Most patients are then switched to a more rigid contact lens. There are many different types of lenses used for keratoconus patients and an optometrist who specializes in keratoconus lenses would be best suited for fitting these lenses. The lens needs to be properly fit to insure the optimal vision, comfort and eye health. Improperly fit lenses can lead to other complications like scarring, infection, and corneal abrasions. If the patient becomes intolerant of the contact lenses and have more difficulty with their vision, the next option would be surgery.
One method for treating more moderate cases of keratoconus is with INTACS. INTACS are small implants that are placed into the cornea to reshape the tissue and add support to the thinning area, which prevents or decreases the bulging of the cornea, creating a more normal, uniform surface to fit with contacts or glasses. It is a less invasive option for some patients who are unable to tolerate contact lenses, and whose only option left is a corneal transplant. The purpose of this surgery is to enable patients to achieve clearer vision wearing glasses or to be able to comfortably wear contact lenses again. It is not meant to correct vision without the use of contact lenses or glasses.
A new technology that is being used to treat keratoconus is called Collagen Cross Linking. It uses UVA rays to strengthen, or stiffen, the corneal tissue, thus making it stronger and less susceptible to progression. Since one possible reason of the progression of keratoconus is that the actual fibers of the cornea are weaker, the cross linking procedure is an attempt to deal with the disease by not reshaping or replacing the abnormal tissue, but trying to strengthen the tissue that is there.
Some patients have keratoconus that has progressed past the point of wearing rigid contact lenses, INTACS or Collagen Cross Linking. In these cases the best surgical option would be a corneal transplant. Corneal Transplantation is a fairly common operation today, and is performed in an ambulatory surgical center, not the hospital, and is done under local anesthetic.
During corneal transplantation there is a central disc removed from the cornea and it is replaced with donor tissue from the local eye bank. There are very strict precautions to ensure that there is no transmission of disease through the donated cornea. The donor tissue is sewn to the eye using extremely fine sutures, finer than a human hair. The knots of the sutures are then buried, so that there is no sensation from the sutures. The sutures may stay in the eye indefinitely. By replacing the abnormal tissue the corneal curvature will be a more normal shape allowing the patient to see clearer with glasses or contact lenses.
Each individual patient with keratoconus is different and should be evaluated in order to find the best treatment for the problem. If you have any further questions about keratoconus please feel free to contact our office.
Browse our online store for contacts and other eye care products.