By Dr. Miguel Morcillo, Consultant Ophthalmologist, specialised in Cornea, Cataract and Refractive surgery, Moorfields Eye Hospital Dubai
The cornea is the transparent layer of the eye that acts as a window and covers the iris, pupil, and anterior chamber. While the cornea may seem like an insignificant part of the eye, it accounts for approximately two-thirds of the eyes’ total optical power; responsible for focusing light that enters the eyes and refracting it.
Although the cornea is powerful, it is a very delicate part of the eye that is susceptible to damage. Fortunately, if the cornea is damaged and vision problems develop, corneal transplant surgery could help to restore vision. Dr. Miguel Morcillo walks us through what corneal transplants are, why one may need the procedure and the associated risks involved.
What is a corneal transplant?
A corneal transplant is a procedure that replaces a patient’s injured cornea. During this procedure, the surgeon will remove the patient’s damaged or diseased corneal tissue and replace it with healthy corneal tissue from the eye of a donor.
All corneal transplant operations are performed under general or local anaesthetic and are typically quite simple, lasting around one hour, and providing same-day discharge. There are four kinds of corneal transplant that can be performed, each using different methods and different levels of risk.
Deep Anterior Lamellar Keratoplasty (DALK)
DALK removes the outer three layers of the cornea and replaces it with a donor’s layers to give a partial-thickness corneal transplant. This procedure has a 90% rate of achieving a driving standard of vision; however, another surgery or supplemental glasses or contact lenses may be required to completely correct vision. While this procedure may not result in perfect vision, it is relatively low risk and yields full recovery within 18 months.
Superficial Anterior Lamellar Keratoplasty (SALK)
SALK is a partial-thickness transplant performed using human fibrin glue. The procedure is typically performed in cases of anterior stromal opacities, involving less than one-third of the anterior corneal stroma. The main advantages of SALK include decreased incidence of rejection and reduced complications.
Endothelial Keratoplasty (DSAEK and DMEK)
EK offers faster recovery compared to full-thickness grafts and replaces the inside layer of the cornea with a donor layer inserted through a small incision without the need to suture the graft. After this procedure, most patients achieve driving vision, sometimes with glasses, which can take up to six months to see the benefits of and around 18 months for full improvement of vision. Risks are rare, but can be sight-threatening if they occur, including corneal transplant rejection, graft failure, glaucoma and cataract development.
PK is a full-thickness transplant replacing all five layers of the cornea. After this procedure, 75% of patients typically achieve driving vision, possibly needing vision aids or other surgery with full results in around 18 months. While this procedure is relatively riskier compared to other corneal transplants, it can provide better results for patients with severely a damaged cornea. If they occur, complications can be sight threatening, including corneal transplant rejection, graft failure, glaucoma, cataract and high astigmatism.
When to consult a professional?
Your eye doctor might recommend this procedure if you are experiencing eye pain, blurred vision, or vision loss due to various eye diseases, including Keratoconus and Fuchs’ dystrophy. Patients with thinning of the cornea, cornea scarring, clouding or swelling of the cornea, corneal ulcers, or complications caused by previous eye surgery may also be good candidates for the procedure.
Additionally, diabetes, one of the most widespread diseases in the MENA region, can increase a patient’s likelihood of developing cornea damage. This is because diabetic corneal alterations, such as delayed epithelial wound healing, edema, recurrent erosions, neuropathy/loss of sensitivity, and tear film changes are frequent, but underdiagnosed complications of both type 1 and type 2 diabetes.
What are the risk factors?
One of the most concerning complications of cornea transplant is cornea rejection. Rejection is when the body’s immune system identifies the transplanted cornea as a foreign antibody and tries to fight off the transplant.
The risk of rejection varies based on the surgical technique used, as transplants that provide fuller thickness repair are associated with a higher risk of rejection. Additionally, conditions like dry eye, blood vessels growing in the cornea, eyelid problems and eye infections increase the chance of rejection; therefore, patients will be prescribed specialised eye drops to aid in keeping the eye healthy.
Other complications of cornea transplant surgery include infection, glaucoma, bleeding, visual acuity problems, fluid leakage from your cornea, and detached cornea, among others.
For most people, a cornea transplant is remarkably successful in the long-term. However, patients with an extremely high risk of rejection and serious complications may need to visit other solutions as the procedure may prove too dangerous. It is essential to consult a trusted professional before deciding to undergo a cornea transplant to find out what procedure is best for your lifestyle and will provide the best results.