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The cornea is the transparent, highly refractive front part of the eye. The rays that come to the eye in parallel are refracted by the transparent cornea and its oblique front part, and converge to join on the retina then pass through the lens and are focused on the retina. So, to achieve a good visual function, the cornea must be in correct shape and maintain its transparency.
Corneal transplantation (keratoplasty) is a surgical procedure where an opacified or deformed corneal tissue is removed circularly in a certain size and replaced by donated corneal tissue, which is taken from a recently deceased individual with no known diseases, prepared in an appropriate diameter. This is the widely used tissue transplant with the highest success rate.
The recent developments in surgical techniques and materials, use of special materials to preserve the cells, taking the donated cornea in sterile conditions, testing the quality and appropriateness of the tissue, all these further increase the success rate of this surgery.
rencontre des femme sur grenoble Why a corneal transplantation is done?
A corneal transplantation is performed to improve the vision (optic), to treat a corneal disease (therapeutic), to preserve corneal integrity (tectonic), and to correct the appearance (cosmetic).
The most common reason of a corneal transplantation is to improve visual acuity.
The factors that affect the transparency of cornea include scar tissues and blood vessel growth associated with infections; dystrophy caused by deposited materials in the cornea; endothelial deficiency that occurs during an intraocular surgery or with a genetic disease. These are the pathologies that require a corneal transplantation.
The other factors that require a corneal transplantation include a thinned cornea; keratoconus where cornea loses its uniform oval shape and become conic; keratitis nonresponsive to specific antimicrobial therapy; damaged integrity after an accident; or an opacified cornea and occurrence of problems with appearance.
How and where is the corneal tissue supplied to be implanted?
A corneal tissue is supplied by Eye Banks established in various centers in the country. Such centers are responsible to collect the corneal tissue from a recently deceased individual, store it in an appropriate nutritive media, analyze whether the donated tissue is suitable for transplant, and transfer it to the centers where transplant will be performed. The corneal tissue is taken from individuals who have died for some reason but their cornea is healthy. The cause of death must be known to use the corneal tissue. The blood of donor is tested to investigate microorganisms causing infectious diseases such as AIDS, and hepatitis to prevent any diseases be transmitted to recipient.
The cornea is ideally collected within the first 8 hours after death. One of the important points to know is that it is only corneal tissue (approx in 15 mm diameter) that is collected from the deceased individual therefore the deceased individual doesn’t undergo any changes in appearance since there is no need to take the entire eye. A cornea collected from a deceased person and stored in a special nutritive media is examined by a specific microscope in the eye bank to determine whether it is appropriate for transplantation. Ideally, the ones that are suitable for transplant should be implanted in a recipient within 5 days.
Is corneal transplant beneficial to anyone with visual loss?
The structures of the eye, other than cornea, must be normal to benefit from a corneal transplant. The recipient will not benefit from the transplantation if the retina layer is damaged, which picks up the images and sends to the brain. This surgical procedure will not be beneficial if you have a high eye pressure, atherosclerosis, or any diseases that cause intraocular hemorrhage; or you will need extra treatments. It is identified by a detailed examination of an ophthalmologist, eye ultrasonography, and if necessary some tests providing data on the retina.
How a corneal transplantation surgery is performed?
A corneal transplantation surgery is usually performed under general anesthesia. With a microscope, a window of 7.5-8 mm in diameter is removed from the patient’s cloudy cornea by a special round blade, and the transparent corneal tissue taken from the deceased individual is cut in appropriate size and sutured on this site.
If the patient has also cataract, the cataract can be removed during corneal transplantation. You may need to wear glasses or contact lenses after the surgery.