Corneal transplant surgery is the most commonly performed of all transplant operations, with approximately 45,000 corneal transplant procedures being performed in the Unites States each year. The indications for corneal transplant surgery have changed through the years. Pseudophakic bullous keratopathy and aphakic bullous keratopathy (corneal edema secondary to cataract surgery) accounted for 80% of corneal transplants in the 1980s. However, with the improvement of cataract surgery techniques, conditions such as Fuchs’ Dystrophy, Keratoconus, and other corneal dystrophies are now more commonly transplanted.
In 1933, corneal transplants were performed using two razor blades to make a square graft. Patients were hospitalized for two weeks with sand bags on either side of their head to prevent undesirable movement and possible leakage from the wound sites. Since then, there have been major advances in surgical technique including the introduction of the operating microscope (1970s) and better suture needles and materials. Newer instruments and corneal punches have also improved the procedure as have viscoelastics that protect the endothelium – the layer responsible for corneal deturgescence and clarity. Corneal transplants are now routinely performed as outpatient surgery under local anesthesia.
Up until recently, classic corneal transplantation (Penetrating Keratoplasty), a full-thickness procedure, has been the standard transplant procedure where all five layers of the cornea (Epithelium, Bowman’s Layer, Stroma, Descemet’s Membrane, and Endothelium) are replaced. The cornea is secured with multiple sutures (up to 24). Suture removal may start as early as six weeks after surgery depending on technique; all sutures are seldom removed before one year. Sutures cause astigmatism and removal adjusts this astigmatism. Residual sutures can loosen and become infected which may result in graft failure or unwanted permanent astigmatism. This is why it is important for routine follow-up after surgery. Vision can take up to one year to stabilize. Rejection can occur, and because the corneal incisions are vertical there is always a risk of late-wound rupture. Finally, vision could potentially change if a residual suture breaks or degrades (even years post-operatively). Despite all of these concerns, Penetrating Keratoplasty has cured corneal blindness in over one million people throughout the years.
Over the past decade, however, tissue targeted surgical approaches have been introduced specifically for condition of endothelial dysfunction (Fuchs’ Dystrophy, pseudophakic, aphakic bullous keratopathy) with the goal to replace the endothelium leaving the surface and stroma intact. In the most common of these procedures, Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK), the host’s diseased endothelium and Descemet’s membrane are removed and replaced by a posterior layer of corneal stroma, Descemet’s membrane, and endothelium (partial thickness donor). This is accomplished through a shelved temporal limbal incision (5mm). The donor tissue is folded like a taco and inserted into the anterior chamber of the eye, then, using air, it is unfolded. The patient is sent home with an air bubble in the eye which positions the cornea while the patient is lying on their back. There are no sutures holding the cornea in place, only three at the temporal incision site. By eliminating central corneal sutures and corneal surface incisions, the host surface is preserved reducing surgical astigmatism and corneal suture-related complications. This results in faster visual recovery time and decreased risk of late-wound dehiscence (due to greater tensile strength). There is also a reduced antigen load without any surface antigen introduced.
The newest development is Descemet’s Membrane Endothelial Keratoplasty (DMEK) where Descemet’s membrane and endothelium are stripped from both the donor and recipient corneas. In this procedure about 15 microns of recipient cornea are replaced with 15 microns of donor cornea. This is a perfect anatomic replacement done through a 3mm temporal incision with one suture. This again reduces any astigmatism, eliminated interface issues and further decreases the antigen load. The shelved wound is smaller and stronger, the rate of recovery is quicker and the quality of vision much improved. In many patients, this is now the preferred technique.
Obtaining a Donor Cornea
At present, the only source of corneal tissue is from donor tissue. The transplanted corneas come from a donor who has willed his or her cornea for transplantation, or whose family has donated the cornea after the donor’s death. It may be upsetting to look upon the dying patient as a source of replacement tissue, but for most families, the opportunity to give sight to another human is comforting.
All corneas are screened for HIV and Hepatitis, as well as other infectious diseases. The waiting period is usually about four-six weeks. Surgeries are tentatively scheduled with the hospital or surgicenter however the actual surgery will only occur if there is a suitable donor cornea available on the day of surgery. If not, however, the patient may be rescheduled soon after the original date.
Blood samples, EKG, and/or chest X-rays are required (some testing depends upon your age and health status) to clear you for surgery.
The Day Before Surgery
On the day before surgery, our office contacts patients to let them know if an appropriate donor has been found. If so, a nurse from the hospital informs patients in the late afternoon or early evening regarding what time to arrive for surgery. Patients are not allowed to eat or drink anything after midnight.
The Day of Surgery
Corneal transplant surgery is normally done on an outpatient basis and patients are at the hospital for at about 5 hours. All patients should have someone to drive them home.
A nurse interviews the patient about their general state of health and an anesthesiologist will screen you prior to surgery (most corneal transplant surgeries are performed under local anesthesia).
If local anesthesia is used, the physician will inject medication around your eye that will temporarily prevent pain and movement. It will also block your vision during surgery. Sterile drapes will be placed to isolate the eye having the surgery and adequate ventilation will be provided.
If general anesthesia (less frequent) is used, patients awaken in the recovery room and will then be moved to a room in the hospital after about an hour.
A patch and protective shield are placed over the operated eye when surgery is complete.
Patients stay in the hospital for at least an hour after surgery. If Endothelial Corneal Transplant surgery is performed , there will be an air bubble in the eye and positioning, (lying on your back as much as possible) will be very important.
Patients who had local anesthesia are able to resume their regular diet. Patients who had general anesthesia receive liquids for their first meal but are able to resume a regular diet the following day.
The Day after Surgery
The eye dressing will remain in place until the morning following the surgery when patients have their first post-operative appointment.The patch and protective shield will be removed the next morning. Patients are permitted to wear glasses during the day, and a shield must be worn at night. One or the other should be worn at all times.
Eye pain following a corneal transplant is usually minimal. Antibiotic, steroid and possible dilating drops will be instilled to prevent infection and rejection of the donor cornea.
Post-transplant Cornea Care
Antibiotic and dilating drops will be prescribed for one month. Steroid drops may be prescribed for at least one year. Patients and their families are instructed on the proper techniques for instilling eye drops.
If you do not have enough eye medication at home, call us with the name of the medication and the phone number of your pharmacy. It is crucial that you receive every dose of your medication. Please plan ahead if your drops are running low. Avoid running out in the evening or on a weekend or holiday.
You may clean around your eye, but do not rub the eye. If there is crusting, use a clean, wet washcloth to gently wipe the eye once or twice a day. Never put the washcloth into the eye or use the same part of the washcloth twice. Avoid putting any pressure on the eye.
Over the following weeks, you should avoid strenuous activity that causes you to become red in the face, as straining increases pressure in the eye. If it is necessary to cough or sneeze, do so with your mouth open. Do not lift, push, or bend with your head lower than your heart.
Patients are allowed to return to the following activities unless otherwise instructed not to do so by the doctor:
• Patients may return to school or work if it does not involve strenuous activity or lifting.
• Pending the doctor’s advice, patients may drive a car if the corrected vision in the un-operated eye is 20/40 or better.
• Patients may shower – soap must be prevented from getting into the eye.
• Patients may shampoo their hair with their head tilted backwards.
• Patients may do light housework (do not lift, push, or bend with your head lower than your heart).
• Patients may read, watch TV, do needlework until the eye(s) become tired.
Patients are prohibited from doing the following until otherwise approved by the doctor:
• Participate in sports (until approved)
• Strain or do any lifting (any activity which may cause your face to turn red)
• Bend with your head lower than your heart
The Possibility of Corneal Rejection
Your corneal transplant will most likely be successful, however there is a possibility your body will reject the new cornea. Please click here to read more about the possibility of corneal rejection.