Having a PK or DALK corneal transplant

What is a corneal transplant?

The cornea is the normally clear window at the front of the eye. The cornea has three main layers: a thin outer layer called the epithelium, a thick middle layer called the stroma, and a thin inner layer called the endothelium.

The cornea can become cloudy or out of shape from various eye conditions, including injury, infection, and keratoconus. When the cornea loses transparency or becomes irregular in shape, your vision may be reduced.

When this happens, a corneal transplant can be performed where a part of the cornea in your eye is replaced to improve your vision.

What is a PK corneal transplant?

In a PK transplant surgery, the whole of your central cornea is removed and replaced with healthy cornea tissue from a donor.

What is a DALK corneal transplant?

In DALK surgery, only the outer layers of your cornea are replaced. The inner layer (endothelium) is not replaced if the corneal problem is confined to the outer layers (such as in early keratoconus or mild corneal scarring).

Due to the delicate nature of this operation, one in two DALK operations will need to become a PK corneal transplant.

How are PK and DALK transplants performed?

The operation usually takes about two hours. It is performed under general anaesthetic (when you are put to sleep). During the operation, a central circular part of your cornea is removed, and a donor cornea is stitched in its place.

The stitches in your eye should not cause you any discomfort and are usually removed after a year and a half to two years.

Planning transport for your corneal transplant surgery

You must arrange for an escort to take you home from the hospital and have a responsible adult stay with you for 24 hours after your operation. We strongly recommend you go home by car or taxi. We discourage you from travelling by public transport as you will still be recovering from the effects of the operation and anaesthetic.

Before your procedure

Please arrange to take time off work for one to two weeks, as advised by your surgeon. If you perform manual work or drive for work, you may need to take longer off.

On the day of surgery

• Have a bath or shower before coming into the hospital.
• Wear comfortable, loose-fitting clothing.
• Remove all make-up, body piercings, jewellery. You may wear your wedding ring.
• You may wear hearing aids and glasses, but not contact lenses. Please bring equipment to store these.
• Please bring a list of your medications.
• Please bring something to help pass the time, such as a book. You will be in hospital for either the whole morning or afternoon.

If you are having a general anaesthetic (sedation)

• You must not eat and drink for six hours before your operation. This reduces the risk of vomiting under anaesthesia.
• You may only drink small sips of water up to two hours before your operation.
• Please take all your eye drops and your medicines with small sips of water before you leave home in the morning

After your procedure

An eye pad and shield will be placed over your eye after surgery. Please leave them in place overnight and remove them the next morning.

The eye shield should be worn at night for one week after the operation to protect the eye during sleep. Each morning after removing the eye shield, gently clean away any residue around your eyelids with a clean tissue and then put in your eye drops. Wash your eye shield daily using warm water and soap; rinse and dry it carefully.

You will be given eye drops to use at home and instructions on how to use them. If you are running out of eye drops, please contact your GP for a repeat prescription. Please continue with eye drops that you were using prior to surgery unless told to stop.

After the surgery, please avoid:

• Rubbing your eye. If the eye waters, wipe it gently with a clean tissue.
• Getting soap in the eye for two weeks, when showering or washing your face or hair.
• Wearing eye makeup for two weeks.
• Straining or heavy lifting (more than 7 kg) for two weeks.
• Strenuous exercise (eg running, cycling, yoga) for two weeks.
• Swimming or gardening for four weeks.

After a PK or DALK surgery, the eye is permanently at increased risk of injury with blunt force. We advise you against playing any contact sports after undergoing this surgery, due to significant risk of permanent loss of your vision or your eye.

For the first few days after your surgery, please take care when stepping off pavements and going up and down stairs, as your depth perception may be affected.

You may notice redness on the white of the eye – this is not harmful and usually resolves over two to three weeks.

Your eye should not be painful, but you may feel slight discomfort or grittiness. Please make sure you have some over the counter pain relief medication at home.

Your surgeon will advise you when you can obtain new glasses or contact lenses, and when you can return to driving.

Risks and side-effects

Rare but serious complications include:

• 1:1000 sight-threatening infection inside the eye (endophthalmitis)
• 1:1000 sight-threatening bleeding inside the eye
• retinal detachment
• severe inflammation or other rare causes of loss of vision.

Uncommon problems include:

Corneal transplant rejection

This occurs when your immune system rejects the transplant. This happens in 5-15% of patients after PK and can be reversed with eye drops if started promptly. The risk is highest in the first two years but remains a possibility in your lifetime.

To reduce the risk of rejection, you are prescribed a prolonged course of steroid drops. Please do not stop your steroid drops unless advised to do so by the Cornea team.

Corneal transplant failure

This happens when the transplant stops working; your vision and the cornea becomes cloudy. The surgery can be repeated but the success rates of subsequent grafts are usually lower.

Glaucoma (raised eye pressure)

Raised eye pressure may be asymptomatic and can lead to sight loss. Most cases can be managed with eye drops; rarely tablets or surgery may be needed. Please attend your follow up appointments to monitor your eye pressure and your transplant as advised.

Cataract (clouding of the lens)

Cataract usually forms later in life but can form earlier after a corneal transplant. If you already have a cataract, this may be removed at the time of the transplant.

PK or DALK surgery benefits

The main benefit of surgery is to improve your vision. After the operation, you may notice some improvement in vision after a few weeks. However, full improvement in vision is only seen after glasses or contact lenses are fitted, typically between 6-24 months after surgery.

Approximately 75% of patients receiving a PK or DALK have ‘aided’ vision (with either glasses or contact lenses) sufficient to drive legally. Keep in mind that 50% of corneal transplant patients will still need contact lenses to achieve driving vision.

Rarely, the surgery is done to ease discomfort or pain.

Alternatives to PK or DALK surgery

You may choose not to have surgery if you are satisfied with your current level of vision in contact lenses or glasses. However, if you find contact lenses difficult to use, surgery may improve your corneal shape and allow you to wear contact lenses more comfortably.

When to seek help

Your vision will be blurred for one to two weeks, and there will be some grittiness and light sensitivity after the operation. This should improve over time. You should contact us if you experience the following symptoms:

• Pain or headache not relieved by over-the-counter pain medication.
• Increased swelling of the eye.
• Increased sticky discharge.
• Worsening of vision.
• Worsening of redness, pain, or light sensitivity.

During working hours, please contact the Royal Free Hospital switchboard to bleep the eye casualty nurse or the on-call ophthalmologist. If your operation was done at Edgware Community Hospital, you may contact them as well (Monday to Thursday).

Outside of hours or over the weekend, please contact the switchboard who will call the on-call ophthalmologist.

If you are still unable to contact us, you can attend the emergency department at the Royal Free Hospital, who will contact the on-call ophthalmologist.