Deep Anterior Lamellar Keratoplasty (DALK)

A corneal transplant is performed when the cornea (the clear, front window of the eye) has become cloudy or distorted, resulting in a decrease in vision. The diseased part of the cornea is removed and replaced by a cornea provided by an organ donor.

A DALK is a partial thickness corneal transplant. In this operation, only the front part of the cornea is removed, and replaced by the equivalent layers from donor tissue. The transplant is held in place with around 16 stitches (sutures) that remain in the eye for around 18 months before they are removed. After this time, glasses or contact lenses are usually required to optimise your vision.

A transplant is usually performed under general anaesthetic. A DALK is a technically challenging procedure as the layers of the cornea are very thin and therefore it is not always possible to separate the layers successfully, particularly if there is scarring in your cornea. Therefore, it is important that you understand that a penetrating keratoplasty may need to be performed instead. Whether a DALK can be successfully performed is not known until the time of surgery.

A DALK has the advantage of a much lower risk of rejection compared to a penetrating keratoplasty.

There are numerous risks including:

• Rejection – it is therefore important that you stay on your steroid eye drops and you contact the Emergency Department if you suddenly develop a reduction in your vision. The chance of rejection is lower in a DALK than a full thickness (penetrating) keratoplasty
• Failure
• Cataract – a cataract will develop at an earlier age compared to a normal individual due to the surgery and the use of the steroid eye drops
• Raised eye pressure – an increase in your eye pressure leading to glaucoma can occur due to the steroid eye drops. Careful monitoring of your pressure and treatment with pressure-lowering drops can minimise any long term damage from glaucoma
• Astigmatism – an irregular shape to the front surface of the cornea means that most people will need glasses or contact lenses to achieve their best possible vision
• Infection
• Scarring – in a DALK, scarring between the transplant and your own back surface of your cornea may affect your vision
• Blindness – the risk of blindness from the operation is extremely low

It is also important to understand that the junction between your transplant and your own cornea does not regain the same strength as a normal cornea. It is therefore vital that you avoid direct trauma to the eye in the long term as it can cause the edge of the transplant to loosen leading to damage to the internal structures of the eye.