Corneal Transplant

Penetrating Keratoplasty (PK)

A corneal transplant involves replacing a diseased or scarred cornea with a new one. When the cornea becomes cloudy, light cannot penetrate the eye to reach the light-sensitive retina. Poor vision or blindness may result.

If the cornea develops visually significant opacities or irregularities, a traditional penetrating corneal transplant, or PK procedure can be performed.

In corneal transplant surgery, the surgeon removes the central portion of the cloudy cornea and replaces it with a clear cornea, usually donated through an eye bank. A trephine, an instrument like a cookie cutter, is used to remove the cloudy cornea. The surgeon places the new cornea in the opening and sews it with a very fine thread. The thread stays in for months or even years until the eye heals properly (removing the thread is quite simple and can easily be done in an ophthalmologist's office). Following surgery, eye drops to help promote healing will be needed for several months.

Illustration by JirehDesign.com

Corneal transplants are very common in the United States; about 40,000 are performed each year. The chances of success of this operation have risen dramatically because of technological advances, such as less irritating sutures, or threads, which are often finer than a human hair; and the surgical microscope.

Corneal transplantation has restored sight to many, who a generation ago would have been blinded permanently by corneal injury, infection, or inherited corneal disease or degeneration.

Postoperative Complications
Even with a fairly high success rate, some problems can develop, such as rejection of the new cornea. Warning signs for rejection are decreased vision, increased redness of the eye, increased pain, and increased sensitivity to light. If any of these last for more than six hours, you should immediately call your ophthalmologist. Rejection can be successfully treated if medication is administered at the first sign of symptoms.

A study supported by the National Eye Institute (NEI) suggests that matching the blood type, but not tissue type, of the recipient with that of the cornea donor may improve the success rate of corneal transplants in people at high risk for graft failure. Approximately 20 percent of corneal transplant patients reject their donor corneas.

Some information courtesy of National Eye Institute

See Eye Anatomy

Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK)

The cornea, the transparent front "window of the eye", is responsible for about two thirds of the focusing power of the eye.  The cornea's refractive power is actually greater than that of the eye's lens.

The cornea receives its nutrients through the tear film.  A normal, healthy cornea should be transparent, thus devoid of blood vessels and opacities.  Corneal tissue can become damaged through disease or trauma.  This damage can cause scar tissue and opacities in the normally-clear cornea, resulting in a reduction in visual acuity. 

What is DSAEK

Descemet's stripping automated endothelial keratoplasty (DSAEK) involves surgically replacing diseased cornea tissue with donor cornea tissue.  Instead of the entire cornea being removed and replaced, only the damaged posterior (inner) layer of tissue is replaced, making DSAEK a much less invasive option than the traditional method of total corneal transplantation.

This less invasive procedure leads to rapid recoveries and reduces the risks of sight threatening complications like hemorrhaging, infection and wound rupture.

Who is a candidate?

DSAEK is a preferred surgical procedure over corneal transplant, but it is not for everyone.  Only those corneas with defects and damage limited to the inner cornea layer (endothelium) are candidates for DSAEK.  Eyes with corneal scars are not good candidates for DSAEK and will be considered for full corneal transplant surgery.

A common disease that can cause damage to this inner layer of the cornea is Fuchs' Corneal Dystrophy.  This inherited eye disease causes the cornea to swell, opacify and distort vision.

The surgical procedure

DSAEK is an outpatient procedure.  No hospitalization is required.  The entire surgery, including prepping the eye, usually takes between 45 and 60 minutes.

After the eye is cleaned and prepared with a sterile drape, a small incision is made at the edge of the cornea.  Through this tiny incision, the diseased inner layer of cornea is peeled away and removed.  The donor cornea's inner layer is separated from the other layers with a precision machine called a microkeratome.  This ultra-thin "button" of cornea is then carefully folded and inserted into the eye through the incision and attached to the back, inner "dome" of the cornea.  The donor tissue is then held in place with an air bubble until it adheres to its new place in the patient's eye, usually in about 24 hours.

The small incision is then secured with one to three small sutures. 

Recovery time

In most cases, the vision will begin to improve in about one week.  Full recovery is typically 3 months.

What are the differences between DSAEK and Corneal Transplant