The cornea is the front clear window of the eye. A clear cornea is essential to transmit a clear image to the retina, located in the back of the eye. There are many reasons why a cornea could lose its clarity and cause blurry vision. These reasons include scarring caused by traumatic injuries, scarring from corneal infections, and genetic diseases such as Fuch’s (rhymes with “Dukes”) endothelial dystrophy and Keratoconus. Many contact-lens wearers are unaware that they are constantly at risk of getting a corneal ulcer (infection). The risk with soft contact lenses is as high as one in every 250 contact lens wearers per year getting an infection. Most of the time these ulcers leave a small scar that usually does not affect vision. In some cases the infection leaves a dense scar that can decrease vision and require a corneal transplant. The most significant risk factor for contact-lens related corneal ulcers is overnight wear. Even though the FDA has approved soft contact lenses for overnight wear, numerous studies have shown that wearing contact lenses overnight increases the risk of infection 15-fold. Herpes simplex virus which causes cold sores on the lips can also infect the cornea and result in scarring.
A genetic disease called Fuch’s dystrophy is a disease that causes cells in the inner lining of the cornea to die at a faster than normal rate. This lining can also be damaged by previous eye surgeries. This causes the inner lining to gradually lose its ability to keep the cornea dehydrated. The cornea then swells and blurs vision. Keratoconus is a thinning disorder of the cornea which can cause the cornea to assume an irregular shape and can also cause scarring which can decrease vision. Both of these diseases can result in the need for a cornea transplant.
Over 40,000 cornea transplants are performed in the United States every year.
The standard method of cornea transplantation involves removing the central full-thickness portion of the cornea which has lost its clarity and replacing it with a clear donor cornea. The operation is performed on an outpatient basis and usually takes approximately 45 minutes. Full recovery of vision can take four to six months; sometimes less and sometimes more. High astigmatism and unpredictable eyeglass prescription afterwards are common problems. A recent development in cornea transplantation has provided an alternative which avoids the astigmatism problems and lack of refractive predictability associated with conventional transplants. This technique is called Descemet’s stripping endothelial keratoplasty. This method involves transplanting only the inner lining of corneas in which that layer has failed and caused corneal swelling. The technique is also performed on an outpatient basis and takes about 30 minutes. Visual recovery takes place over a three to four month period. If you have a loss of vision related to your cornea, an evaluation by a cornea specialist could help to determine if you may be helped by any of these procedures.
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