Cornea transplant - How cornea transplants are performed

There are a number of different types of cornea transplant procedure, depending on the parts of the cornea that need to be replaced.

Most cornea transplant operations involve transplanting the full thickness of the cornea. However, recent advances in technology mean it is sometimes possible to only transplant part of the cornea.

Full-thickness transplants

A full-thickness transplant is called a penetrating keratoplasty (PK). During this procedure, a circular piece of damaged cornea from the centre of your eye is removed and replaced with the donated cornea. In most cases, a circular cutting instrument (similar to a cookie cutter) called a trephine is used to remove the damaged cornea.

The new cornea is held in place by tiny stitches, which sometimes form a star-like pattern around the edges. You may be able to see the stitches faintly after the operation.

The operation may be done under local anaesthetic or general anaesthetic and usually takes one to two hours. If local anaesthetic is used, you won't be able to see through the eye during the operation as the anaesthetic temporarily stops the eye from working.

Most people have to stay in hospital for one to two days after a full-thickness cornea transplant.

Partial-thickness transplants

Recently, techniques have been developed that allow only parts of the cornea to be transplanted. These techniques aren't suitable for everyone in need of a cornea transplant and they can take longer to perform, but they often have a faster recovery time and a lower risk of complications.

There are several different techniques your surgeon may use, depending on which layers of the cornea are transplanted. Generally, these techniques can be broken down into transplants involving the front portion of the cornea and those involving the back portion.

Most of these procedures are carried out using cutting instruments, such as a trephine, although lasers are sometimes used. These procedures can be carried out using either local or general anaesthetic, and you may be able to go home on the same day of the procedure.

Transplanting the front portion of the cornea

The main techniques for transplanting the front parts of the cornea include:

anterior lamellar keratoplasty (ALK) –removing and replacing only the outer layers of the cornea
deep anterior lamellar keratoplasty (DALK) – removing and replacing the outer and middle layers of the cornea, but the inner layers are left intact

As with a penetrating keratoplasty, stitches are used to fix the donated cornea in place during both of these procedures.

Transplanting the back portion of the cornea

The main techniques for transplanting the back parts of the cornea include:

Descemet's stripping endothelial keratoplasty (DSEK) – replacing the inner lining of the cornea together with about 20% of the corneal supporting tissue (corneal stroma)
Descemet's membrane endothelial keratoplasty (DMEK) – replacing only the inner layer of cells of the cornea

DMEK is a new technique that allows faster and near complete visual recovery. It has low long-term risks, such as rejection (less than 1%).

Stitches aren't used during either of these procedures. Instead, the donated tissue is held in place using a temporary air bubble.