Cornea, Contact Lens and Corneal Transplantation
Surgery in which the outermost layer of the eye, the cornea, is replaced is called corneal transplant or keratoplasty. The corneal tissue used for this operation; It is obtained from authorized eye banks in Turkey and abroad. Diseased or damaged corneal tissue may become cloudy, edematous (swell), or thin and lose its proper architectural structure. This affects the light passing through the corneal layer and causes a blurry, foggy image. If the clouding or thinning of the cornea reduces vision and this decrease affects the patient’s quality of life, corneal transplantation is performed.
How is a cornea transplant done?
In corneal transplant surgeries, both donor and recipient corneas are prepared with surgical instruments specially designed for this surgery. The instruments and knives used in transplant surgeries make millimetric incisions and enable the operation to take place. Thanks to laser technology, it is possible to perform the corneal transplant operation completely without a knife. Thanks to femtosecond lasers, both the recipient cornea and the donor cornea can be prepared with thinner incisions to be more compatible with each other.
What are the diseases that require corneal transplantation?
Corneal transplantation is not applied for every eye disease. The diseases in which corneal transplantation is applied can be listed as follows:
- Corneal edema after unsuccessful cataract surgery
- Diseases such as keratoconus, in which the surface map of the cornea is thinned and distorted
- Genetic inherited corneal diseases – corneal dystrophies
- Corneal staining after infections, especially herpes, and contact lens keratitis
- Accident – damage to the cornea after trauma
- Rejection of previously transplanted corneal tissue
After the transplant, there is no change in daily life other than heavy exercise and avoidance of impact to the eye. After the surgery, patients return to their normal lives within a week at the latest. Check-ups are usually done on the 1st day, 1st week, 1st month, 3rd month, and then once every 6 months after the surgery. If necessary, after all, procedures, the patient is given glasses and contact lenses.
Corneal transplantation is performed under sterile conditions with the help of an operating microscope. Except for the corneal tissue, the equipment and technology to be used in the surgery differ according to the transplant technique. In full-thickness corneal transplants, after the damaged or cloudy corneal tissue is removed, the donor corneal tissue is fixed to the eye with stitches. These sutures are removed one by one, 6 months after the surgery, in parallel with the wound healing. Although there is better vision immediately after the surgery than before, the best vision is obtained after 6 months – 1 year, after removing the stitches that cause astigmatism and giving appropriate glasses or contact lenses. In seamless corneal transplantation, after the donor corneal tissue is prepared manually, with special devices called microkeratomes or with the help of a laser, it is placed seamlessly on the inner surface of the recipient’s eye. A small air bubble injected into the eye is also used to fix the graft. After corneal transplant surgery, patients use eye drops for a while to prevent infection and rejection reactions.
Keratoconus is the most important disease in which the cornea becomes thinner, astigmatism progresses, and this architectural structure deteriorates. Collagen fibers in the cornea are normally tightly interconnected. However, the bonds between these fibers weaken due to genetic predisposition or rubbing the eye too much, and the cornea is pulled forward and slightly belly-down due to gravity. In this case, progressive myopia and astigmatism that do not improve with glasses occur.