Corneal Grafts / Corneal Transplantation
There are many conditions which result in scarring or swelling of the cornea that can interfere with the clarity of vision or cause discomfort. In some instances, the only possible solution is to replace part or all of the cornea with material from a tissue donor. These procedures are called ‘corneal transplants’ or ‘corneal grafts’.
The common conditions which lead to corneal grafting include;
- Scarring from infections – especially Herpes Simplex, fungi and acanthamoeba
- Scarring from the eyelashes rubbing on the cornea which is called trichiasis
- Eye diseases e.g. keratoconus hyperlink to keratoconus page
- Hereditary problems which affect the various layers of the cornea e.g. Fuchs’ Corneal Endothelial Dystrophy
- Complications from trauma and chemical injury
- Complications of previous eye surgery
- Graft rejection following earlier transplant surgery
Types of Corneal Graft
There are three main approaches to corneal transplantation. The choice of technique depends on the nature of the problems with the cornea.
Penetrating Keratoplasty involves the replacement of all the layers of the cornea. This is the traditional approach to corneal grafting in which a circular full thickness section of the central cornea is removed using a device called a trephine and then a similar sized piece of tissue is sutured into place with delicate sutures. It has the advantage of removing all the scarred or damaged tissue but does weaken the eye structurally and is associated with a higher rate of rejection and failure.
Endothelial Keratoplasty is a technique used when the main problem with the cornea involves the cell layer on its inner surface called the endothelium. This single layer of cells is responsible for keeping the cornea clear of fluid. If it becomes damaged the cornea becomes swollen and hazy. The epithelium, the cellular layer on the surface, forms tiny blister-like spaces which break down and cause discomfort. The endothelium can be affected by genetic conditions and also be damaged by other eye diseases and surgery.
During endothelial keratoplasty only the very thin layer on the back of the cornea is exchanged – a thin disc of donor tissue with replacement endothelium is applied to the back of the cornea using a special introducer and then held in place temporarily by an air bubble whilst it adheres to the back surface of the recipient cornea. Because there is only a very small amount of donor material involved the risk of rejection is reduced.
Lamellar Keratoplasty is used when the corneal damage is confined to the superficial part of the cornea. A trephine is used in the same way as for a full thickness penetrating graft, but cuts only part thickness through the stroma. The part of the cornea to be removed is then undermined with special blades and replaced with a similar sized piece of donor material. This technique preserves more structural strength in the cornea compared to penetrating keratoplasty and is less prone to rejection.
If you have a corneal problem Dr Rasha Altaie our corneal subspecialist will be pleased to advise you on the best approach.