Corneal transplantation or keratoplasty

Corneal transplantation, also known as keratoplasty, is a surgical procedure where a damaged or diseased cornea is replaced by donated corneal tissue (the graft) in its entirety (penetrating keratoplasty) or in part (lamellar keratoplasty). The graft is taken from a recently deceased individual with no known diseases or other factors that may affect the viability of the donated tissue or the health of the recipient.

The cornea is the transparent front part of the eye that covers the iris, pupil and anterior chamber. The corneal transplantation is performed when medicines, keratoconus conservative surgery and cross-linking can not heal the cornea anymore.

Types of keratoplasty:

Penetrating keratoplasty

A trephine (a circular cutting device) is used by the surgeon to cut the donor cornea, which removes a circular disc of cornea. A second trephine is then used to remove a similar sized portion of the patient's cornea. The donor tissue is then sewn in place with sutures.

Antibiotic eyedrops placed, the eye is patched, and the patient is taken to a recovery area while the effects of the anesthesia wear off. The patient typically goes home following this and sees the doctor the following day for the first post operative appointment.

Lamellar keratoplasty

Encompasses several techniques which selectively replace diseased layers of the cornea while leaving healthy layers in place. Advantage includes improved tectonic integrity of the eye. Disadvantages include the technically challenging nature of these procedures which replace portions of a structure only 500 µm thick, and reduced optical performance of the donor/recipient interface compared to full thickness keratoplasty.

Deep Anterior Lamellar Keratoplasty

In this procedure, the anterior layers of the central cornea are removed and replaced with donor tissue. Endothelial cells and Descemets membrane are left in place. This technique is used in cases of anterior corneal opacifications, scars, and ectatic diseases such as keratoconus.

Endothelial Keratoplasty

Replaces the patient's endothelium with a transplanted disc of posterior stroma/Descemets/endothelium (DSEK) or Descemets/endothelium (DMEK).

This relatively new procedure has revolutionized treatment of disorders of the innermost layer of the cornea (endothelium). Unlike a full thickness corneal transplant, the surgery can be performed with one or no sutures. Patients may recover functional vision in days to weeks, as opposed to up to a year with full thickness transplants.

During surgery the patient's corneal endothelium is removed and replaced with donor tissue.

Patients with endothelial transplants frequently achieve best corrected vision in the 20/30 to 20/40 range, although some reach 20/20. Optical irregularity at the graft/host interface may limit vision below 20/20.

Why the Procedure is Performed

Indications for corneal transplantation include the following:

• Optical: To improve visual acuity by replacing the opaque or distorted host tissue by clear healthy donor tissue. The most common indication in this category is pseudophakic bullous keratopathy, followed by keratoconus, corneal degeneration, keratoglobus and dystrophy, as well as scarring due to keratitis and trauma.
• Tectonic/reconstructive: To preserve corneal anatomy and integrity in patients with stromal thinning and descemetoceles, or to reconstruct the anatomy of the eye, e.g. aftercorneal perforation.
• Therapeutic: To remove inflamed corneal tissue unresponsive to treatment by antibiotics or anti-virals.
• Cosmetic: To improve the appearance of patients with corneal scars that have given a whitish or opaque hue to the cornea.

After the Procedure

You will go home on the same day as your surgery. Doctor will give you an eye patch to wear for about 1 to 4 days.

 Doctor will prescribe eye drops to help your eye heal and prevent infection and rejection.

Your doctor will remove the stitches at a follow-up visit. Some stitches may stay in place for as long as a year, or may not be removed at all.

The risks are similar to other intraocular procedures, detachment or displacement of lamellar transplants.

There is also a risk of infection. Since the cornea has no blood vessels it heals much more slowly than a cut on the skin. While thewound is healing, it is possible that it might become infected by various microorganisms. This risk is minimized by antibiotic prophylaxis (using antibiotic eyedrops, even when no infection exists).

There is a risk of cornea rejection, which occurs in about 20% of cases.^[

References:

http://www.nlm.nih.gov/medlineplus/ency/article/003008.htm

http://en.wikipedia.org/wiki/Corneal_transplantation

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