Penetrating Keratoplasty

What is the cornea?

The cornea is a transparent tissue that acts as the front window of the eye, covering approximately the width of the coloured iris. It plays a vital role in focusing light onto the back of the eye, allowing us to see. Our cornea is made up of three major layers: The outside epithelial layer, the middle or stromal layer and the inner, endothelial layer.

What is a penetrating keratoplasty?

A full-thickness corneal transplant, where the entire central portion of the cornea is removed and replaced by a donated cornea, is known as a penetrating keratoplasty (PK). In cases where a partial thickness corneal transplant is inadequate to treat the corneal problem, a full thickness corneal transplant will be recommended.

Ophthalmologists perform over 40,000 corneal transplants a year. Full thickness transplants have been the gold standard for several decades to treat corneal disease requiring a transplant. Of all the transplant surgeries done – including lung, kidney, and heart – corneal transplants are the most common and the most successful.

What conditions can affect the cornea requiring a corneal transplant?

here are several conditions that can be treated with a corneal transplant. These include:

1. Keratoconus

2. Fuchs’ Dystrophy

3. Scarring after trauma or infection (e.g. herpes)

4. Prior corneal rejections

5. Inherited Dystrophies resulting in opacities within the cornea (e.g. Lattice or Granular Dystrophy)

6. Corneal failure after a previous eye surgery

What happens if you decide to have a corneal transplant?

Before Surgery:

Once it has been determined that you are a suitable candidate and the surgery date has been scheduled, it is important to ensure a suitable donor is available. We work closely with the Eyebank of Ontario in order to ensure the most appropriate tissue is used. Oftentimes a match is found, but sometimes a surgery will need to be postponed if the appropriate cornea is not available.

Before the tissue is released, the eye bank perfoms multiple tests on the tissue to ensure health and viability.

The Day of Surgery:

Surgery is typically done on an outpatient basis with local anesthesia (eye drops/injections around the eye) and intravenous sedation. You will be sedated and pain free during the procedure, but still awake, usually in a dream-like state. The surgery itself takes about 90 minutes during which your cornea is removed and the donor cornea sutured into place. It is extremely important to remain absolutely still during the procedure as sudden movements may result in sub-optimal surgical results. After the procedure is finished, gauze and a plastic shield will be placed over the eye.

After Surgery:

You will typically be able to go home after a short stay in the recovery area, but you should plan to have someone drive you home. Usually no drops are needed in the operated eye the night following surgery. Be careful not to press your eye. The eye should feel sore, but not painful. If it does, you should call your surgeon immediately. The eye patch will remain on the eye overnight and will be removed the following morning when the surgeon sees you for your post-operative visit.

Over the next months, your stitches may be gradually removed, depending on your healing and prescription. Recovery from a full-thickness transplant can take up to a year, or longer, but your vision should improve gradually as the months go by. Maximal vision is usually achieved with glasses or contact lens (i.e. hard contact lens).