Keratoconus - Corneal Transplant
Although only 20-25% of those with keratoconus ultimately require corneal transplant surgery, for those who do, it is a crucial and sometimes frightening decision. However, those who know what to expect before, during and after surgery are better prepared and feel more in control of their health care.
The options in corneal transplant for keratoconus are a penetrating keratoplasty (PK) (full thickness cornea transplant) and deep anterior lamellar keratoplasty (DALK) surgery.
Compared to conventional full thickness corneal transplantation surgery, DALK surgery has several advantages. Unlike conventional corneal transplantation surgery wherein a central disc of full thickness cornea is entirely replaced with donor tissue, in lamellar keratoplasty the healthy inner layer of the patient’s cornea is retained and not sacrificed. (this layer called the endothelium is the most vital layer of the cornea responsible for maintaining the corneal clarity). Only the outer 80 -90% of the cornea is replaced with healthy donor tissue. The other advantage of lamellar keratoplasty, is that as the inner layer is retained, the immune cells of the body do not recognize the outer donor tissue as being foreign. Hence there is no risk of endothelial rejection with lamellar keratoplasty, unlike full thickness graft wherein steroid therapy has to be continued for years to prevent graft rejection episodes. Dr Vinay Agrawal has been performing deep anterior lamellar keratoplasty since 2004, and currently performs the same in all his patients with advanced keratoconus. However, every patient may not be a suitable candidate depending on the presence or absence of hydrops and scarring in the given cornea.
Once the decision for corneal transplant has been made, you will be less anxious and feel more in control if you know what to expect – what the “normal” routine is for this type of surgery. The more information you have, the more prepared you will be.
It is a good idea to check with your insurance company prior to scheduling your surgery to check your coverage and any pre-authorization requirements. Ask exactly what will be covered and what will not. Ask especially about your post operative office visits, glasses and/or contact lenses.
A few days prior to surgery a general medical examination and routine laboratory tests (such as blood count and EKG) are done to insure that you are well enough to undergo surgery. You should not use aspirin for 2 weeks prior to surgery, since it tends to cause bleeding during surgery. Antibiotic drops are generally started one day before surgery to protect the eye from infection.
Do not eat or drink anything after midnight before the surgery (ask your doctor about taking prescription medications the day of the surgery). Dr.Vinay Agrawal or his team members will give you the precise instructions.
In most cases, the surgery is done on an outpatient basis- you enter the hospital or surgery center a few hours prior to surgery and leave that same day- generally a few hours after the surgery. In the “pre-op” waiting area, you will be “prepped”- medication will be given to help you relax before surgery. A needle attached to tubing may be inserted to deliver fluids and medications into your vein and EKG leads may be attached to your chest in order to monitor your heart. These are safety precautions.
Local or general anesthesia can be used for this procedure. The decision as to which type is used should be discussed with your surgeon preoperatively and is based on your age, general health, length of surgery, and your doctor’s preference and your anxiety level.
In the operating room, your eyelids are carefully washed and covered with a sterile plastic drape. Oxygen is occasionally provided by a plastic tube placed near the nose. Patients often doze off during the operation, and most are left with vague recollections of a short procedure, although some remember all of it.
The entire procedure is done under a microscope. A circular cookie cutter-like instrument, called a trephine, is used to remove the center of the diseased cornea. A “button” of similar size is cut from the donor cornea. This donor tissue is then sewn in place with extremely fine nylon sutures.
At the conclusion of the procedure, a patch and shield are applied to protect the eye. You will then be taken to the recovery room to wait until you are fully awake before being discharged.
After surgery, you should rest the remainder of the day. Post surgical pain varies from person to person. Typically there is either no pain or only slight soreness for a few days which is usually relieved by Tylenol. Discuss pain management with your surgeon before the surgery and fill prescriptions to have available if needed afterwards.
The operated eye is patched until the surface epithelium (top layer of the cornea) is healed, usually 1 to 4 days. Do not remove the patch. The doctor will see you the day after surgery, remove the patch and determine if it needs to be worn longer. You will also receive detailed instructions at this visit. It’s a good idea to bring someone with you- two pair of ears are better than one! Be sure you really understand the instructions, ask questions if something is unclear.
The eye drops are very important- be sure you know exactly when you should use them. Make your next appointment, usually in three to seven days. Be sure you know how to contact the doctor if there is a problem or you have questions.
After the patch is removed, it is important to protect the eye from accidental bumps or pokes. Typically, for several months after surgery, patients wear glasses during the day and a metal or plastic shield at night to protect the eye from trauma while sleeping. Since the new cornea is delicately sutured in place, a direct blow to the eye must be avoided. Contact sports are discouraged after corneal transplant. Otherwise, normal activity can be resumed within a few days. After the first day, shaving, brushing teeth, bathing, light housework, bending over, walking, reading, and watching TV will not hurt the eye.
Because the cornea has no blood supply, the transplant heals relatively slowly. Sutures are left in place for three months to one year, and in some cases if the vision is good, they are left in permanently. The sutures are buried and therefore don’t cause discomfort. Occasionally, they do break and then need to be removed. Often they are removed, adjusted or loosened to improve vision. Suture adjustment and removal are simple, painless office procedures.
The sutures used in corneal transplants are made of a monofilament nylon and are quite small (22 microns – 1/3 the thickness of a human hair). There are many different suturing patterns used by surgeons the world over. All of these suture techniques are effective. Some are utilized because of the surgeon’s preference and training. Other suturing techniques are employed depending on the specific problem for which the transplant is being done. In some cases, surgeons will use 16 individual (“interrupted”) sutures; others use a continuous (“running”) suture, which is much like a hemstitch. Still others routinely use a combination of both types. In all cases, the results are more or less equivalent.
Vision gradually improves as the new cornea heals. There is often useful vision within a few weeks. However, in some cases, it may take several months to a year for full vision to develop.
To prevent rejection of the new cornea, steroid eye drops are used for several months after surgery. In some cases, low dosage steroid drops are continued indefinitely. Unlike oral steroids, steroid eye drops cause no side effects elsewhere in the body. Occasionally other eye medications are necessary.
It is important to call immediately (including weekends, evenings, and holidays) if you notice any unusual symptoms, including Redness, Sensitivity to lights, Vision loss, or Pain (“RSVP”). Flashing lights, floaters, and loss of peripheral vision should also be reported immediately.
Postoperative care is extremely important and by far the most time-consuming part of having a corneal transplant. The eye is checked the day after surgery, several times in the first two weeks, at gradually longer intervals over the first year, and usually yearly thereafter.
There is every reason to believe your graft will succeed and last a lifetime. With proper care and prompt attention to any sign of rejection the graft will remain clear and healthy.