What Is the Cornea and What Is Its Function?
The cornea is the clear outermost layer of the eye. It plays an important role in providing clear vision by refracting the incoming light onto the lens, which is then refocused by the lens onto the retina (an area where conversion of light into vision occurs).
A diseased cornea prevents light rays from reaching the retina. This leads to poor vision and in some cases, a corneal transplant may be necessary to restore your visual function.
What Is a Corneal Transplant?
Corneal transplant surgery involves the removal of the damaged cornea and replacement with a healthy donor cornea.
What Are the Different Types of Corneal Transplant?
There are two main types of corneal transplants:
- Full thickness corneal transplant (Penetrating Keratoplasty).
- Partial thickness corneal transplant, which includes either transplanting the outer layer of the cornea (Anterior Lamellar Keratoplasty) or the innermost layer (Endothelial Keratoplasty).
The corneal specialist will advise you on the appropriate surgery according to your child's condition.
Why the National University Hospital?
The Pediatric Corneal Transplant Team at the National University Hospital is a dedicated team formed by corneal specialists, paediatric ophthalmologists, glaucoma¬tologists, optometrists, paediatric transplant team and anaesthetists. This multi-disciplinary care is especially important in paediatric cases with a high risk of rejection and graft failure. We offer com¬prehensive pre- and post-transplant evaluation, in¬cluding individualised peri-operative immunosuppression and post-operative visual rehabilitation to prevent graft rejection, thereby optimising visual outcome.
Who Will Need a Corneal Transplant?
Corneal transplants can be used to treat both congenital and acquired corneal diseases.
The common congenital causes of corneal opacities/ oedema include congenital hereditary endothelial dystrophy, posterior polymorphous corneal dystrophy, congenital hereditary stromal dystrophy, Peters’ anomaly, congenital glaucoma, sclero-cornea, epibulbardermoid, or metabolic disorders.
The common acquired causes of corneal opacities/ oedema include trauma-related corneal injury, corneal scars, keratoconus, keratoglobus, Stevens-Johnson syndrome, toxic epidermal necrolysis, etc.
How Is a Corneal Transplant Performed?
Corneal transplant is performed under general anaesthesia. The diseased cornea is removed and replaced with a clear donor cornea button, which will then be secured in place with sutures.
In an Endothelial Keratoplasty, a gas bubble will be injected into the eye to tamponade the transplanted graft in place. It is important to maintain a post-operative supine position for 1 - 2 days in these cases.
The surgery is usually performed as a day surgery procedure. Admission may be required in high risk patients and a pre-operative anaesthetist assessment may be required.
What Is the Success Rate of Corneal Transplant?
Overall, more than 90% of corneal transplants are successful. Although many patients develop astigmatism that may lead to certain extent of visual blurring, most patients find their vision significantly improved gradually over the first few months after a cornea transplant.
What Are the Risks of a Corneal Transplant?
Risks of corneal transplants include, but are not limited to ocular bleeding, infection such as keratitis or endophthalmitis, glaucoma, graft rejection, cataract formation, retinal detachment, etc. Operative risks also include that of general anaesthesia.
What Is Corneal Graft Rejection and How Is It Treated?
Graft rejection is a known complication of corneal transplantation. In graft rejection, the immune system identifies the donor cornea as “foreign” tissue and attacks it. Rejection can develop any time after the transplantation. However, it is the commonest in the first 2 years post-operatively. Graft rejection occurs in about 20% of corneal transplants. In most cases, it can be treated successfully with immunosuppressive therapy. Repeated transplantations have higher risk of rejection and failure and will require more intensive immunosuppressive therapy.
What Is the Care Required After Corneal Transplant?
Frequent administration of topical steroid eyedrops for at least 5 years (depending on the type of transplant) after corneal transplant is essential to reduce the risk of graft rejection. Infant or young children may not tolerate the administration of eyedrops and this can be a challenge for parents and other caregivers.
Infants and young children may be unable to cooperate with post-operative examinations. Therefore, examinations under sedation or anesthesia may be frequently required after a corneal transplant. Suture removal is usually performed a few months to years later, depending on the rate of recovery, presence of suture-related complications, and the degree of induced-astigmatism.
What Is the Long-Term Care After a Corneal Transplant?
Corneal transplantation is the first step in visual rehabilitation. Most infants and children who have undergone keratoplasty have some degree of amblyopia (‘lazy eye’). This is due to visual deprivation prior to surgery, graft astigmatism, anisometropia, or a combination of the above. Amblyopia can lead to permanent vision loss. Hence, it is imperative that their visual rehabilitation begins as soon as possible. Your child will be co-managed with a Paediatric Ophthalmologist to optimize his/her post-operative visual recovery.
What Can You Do as the Caregiver at Home?
Children tend to rub their eyes during the healing period and this can lead to broken sutures and corneal wound dehiscence, which may increase the risk of rejection and infection. You will need to observe for any increase in eye redness, corneal haziness or opacities. You will also need to be alert if your child reports a drop in vision, or is in pain. In these instances, please make an early appointment to see us as soon as possible.
Where Can I Find out More Information?
Book an appointment with the NUH Eye Surgery Centre for a comprehensive eye check-up and recommendations for your individualised treatment plan.