Corneal Transplant Surgery
What is a corneal transplant?
A corneal transplant is where the abnormal cloudy or scarred patient’s cornea is removed and a donor cornea (the clear window on the front of the eye, which has been obtained from someone who has donated their cornea) replaces the abnormal patient’s cornea.
When is a corneal transplant needed?
A corneal transplant may be needed when the cornea is permanently scarred, or the corneal shape is very abnormal (as in keratoconus) or when the endothelial pumping cells at the back of the cornea are not functioning well (as in Fuchs dystrophy).
A corneal transplant (also known as a corneal graft) is only worth doing when the inside of the eye (retina and optic nerve) is still functioning well. The camera analogy is that there is no purpose in replacing the clear lens in the camera if the photographic components are not working. Conditions that may have damaged the inside of the eye are glaucoma, optic nerve disease, retinal detachment, severe inflammation or infection inside the eye.
What type of corneal transplant do I need?
There are two principal types of corneal transplant: Partial thickness (or lamellar graft) or full thickness (or penetrating graft). Miss Saw will advise you of the type of transplant best suited to your condition.
Endothelial partial thickness grafts are a recent innovation. The results of thousands of patients worldwide have now been published and Miss Saw was one of the first 4 surgeons carrying out this procedure at Moorfields Eye Hospital, London in 2006. Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK) is a partial thickness endothelial graft where a layer of cornea is cut using a microkeratome blade (DSAEK). This is being replaced by Descemet’s Membrane Endothelial Keratoplasty (DMEK) which has a faster visual recovery and improved vision.
DMEK (Descemets membrane endothelial keratoplasty)
DMEK is an endothelial graft containing only the delicate Descemet’s membrane and endothelium. DMEK is the newest method of surgery, which gives excellent rapid restoration of vision. However it can be associated with a higher rate of dislocation, necessitating more than one operation.
The benefits of DSAEK or DMEK are a smaller operation for the eye compared to a penetrating graft, as the surgery is carried out through a keyhole incision, and requires only a few stitches to close the wound. This leaves the eye much stronger than after a penetrating graft, and also eliminates the problems of regular and irregular astigmatism that accompany all penetrating grafts. This speeds up the recovery period.
Following DSAEK or DMEK surgery, vision meeting the licensing standard for driving or better (a Snellen acuity of 6/12 plus) is achievable with glasses for the average patient.
Deep anterior lamellar grafts (DALK)
Deep Anterior Lamellar Keratoplasty (DALK) operations have become more widely used because of the benefits of reduced rejection and graft failure, and the development of better techniques for doing the surgery. Anterior lamellar grafts are only suitable for use in conditions affecting the front layer (epithelium) and central layer (stroma) of the cornea. A lamellar graft will not become “clear” if the posterior layer of the cornea (endothelium) is diseased or damaged. The down side is that the technique of deep anterior lamellar keratoplasty can be technically challenging, and if the endothelium is perforated during the surgery the vision may not recover without a penetrating graft. The surgeon can convert to a full (or penetrating) graft at the time if this happens.
Also the vision after a successful penetrating graft can be better than that following a successful lamellar graft, although the difference is small and patients can expect to meet the driving standard after both types. In a proportion of cases, the vision after an anterior lamellar graft is as good as with a penetrating graft.
Penetrating (full thickness) corneal grafts
Penetrating grafts have been the most widely carried out transplant for all types of corneal disease for over 40 years. However this type of graft is only mandatory if there is deep corneal scarring OR when the corneal disease involves both the endothelium AND the stroma.
The down side of a penetrating graft is that transplanting the endothelium may lead to rejection, which is the commonest complication of this type of graft (about 20% for low risk cases), and leads to graft failure in some. Also the donor endothelium has a limited lifespan.
What are the risks and complications associated with corneal transplant surgery?
- Dislocation of the transplant, necessitating a second operation to re-attach the graft, or a repeat DMEK.
- Corneal graft rejection
- Primary donor transplant failure
How much time should I plan off work for corneal transplant surgery?
At least 1 week.
How soon can I fly or travel overseas after corneal transplant surgery?
Providing there is no more air or gas inside the eye, one can fly or travel overseas within 1-2 days. It may be necessary to wait for at least 1-2 weeks for the air or gas to absorb.
Are there any restrictions I need to be careful of after corneal transplant surgery?
Having one week off work will help your eye recover. Walking and light aerobic exercise will not harm the eye. Avoid accidental direct trauma to the eye. Rugby and other contact sports, and gardening, can be associated with accidental direct trauma to the eye. Ensure that you wear appropriate eye protection for these activities, if they cannot be avoided.
Direct trauma to the eye poses a lifelong risk of incurring permanent damage to any eye that has had a penetrating graft. The risk associated with direct trauma to the eye is much reduced after anterior or posterior lamellar grafts.
A pad will be placed on your eye after the surgery. This pad can be removed the following morning when the eye drops are commenced. Two different eye drops are used postoperatively: one is an antibiotic to prevent infection, the other is a steroid drop to reduce inflammation. You will be given a plastic shield to protect your eye at bedtime. Use this every night for one week.
You will be reviewed at 6-weekly to 3-monthly intervals for the first 12 months after corneal graft surgery, unless conditions arise that require more frequent review. You will have blurred vision for some time postoperatively. The recovery period for good vision is very prolonged (at least 12 months, usually 18-24 months) for PK and DALK, although most patients will notice an improvement within a few days of surgery. Vision recovers more rapidly after DMEK and DSAEK, usually by 1-3 months.
There is a lifelong risk of rejecting a corneal transplant. Diligent use of steroid drops as instructed postoperatively, and having the transplant checked urgently by Miss Saw or another eye specialist in an emergency, if at any stage if the eye becomes red, sore, irritated or the vision worsens, will prevent damage to the transplant as a result of rejection. Graft rejection does not cause pain.
Patients receiving a corneal transplant may need cataract surgery, glaucoma surgery or a repeat corneal graft many years later. It is possible that the corneal graft may fail at any time, needing a repeat graft. In some cases the graft may last more than 30 years.
Why choose Miss Saw for your corneal transplant treatment?
Valerie Saw is an expert consultant ophthalmic surgeon and an outstanding surgeon. As a Member of the Council of the British Society of Refractive Surgeons, and an invited Examiner for the Royal College of Ophthalmologists’ Certificate for Laser Refractive Surgery in the UK, she is recognized by her peers for her expertise in cornea, lens and laser eye surgery. She has been voted amongst the top 10 Laser Eye Surgeons in the UK by patients, for her outstanding surgical skills.
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