Corneal transplantation, also known as corneal grafting, is a surgical procedure where a damaged or diseased cornea is replaced by healthy donated corneal tissue (the graft). When the entire cornea is replaced it is known as penetrating keratoplasty, when only part of the cornea is replaced it is known as lamellar keratoplasty and when the back layer of cornea is replaced it is known as endothelial keratoplasty.
The cornea is the transparent front part of the eye that covers the iris, pupil and anterior chamber. A graft replaces central corneal tissue, damaged due to disease or eye injury, with healthy corneal tissue donated from a local eye bank. An unhealthy cornea affects your vision by scattering or distorting light and causing glare and blurred vision. A cornea transplant may be necessary to restore your functional vision. The graft is taken from an organ donor with no known diseases or other factors that may affect the chance of survival of the donated tissue or the health of the recipient.
Why is it done?
A healthy, clear cornea is essential for good vision. If your cornea is damaged due to eye disease or eye injury, it can become swollen, scarred or severely misshapen and distort your vision. A cornea transplant may be necessary if eyeglasses or contact lenses can’t restore your functional vision, or if painful swelling can’t be relieved by medications or special contact lenses.
Some of the indications of corneal transplant include
- Optical: To improve visual acuity by replacing the opaque or distorted host tissue by clear healthy donor tissue. The most common indication in this category is pseudophakic bullous keratopathy, followed by keratoconus, corneal degeneration, keratoglobus and dystrophy, as well as scarring due to keratitis and trauma.
- Tectonic/reconstructive: To preserve corneal anatomy and integrity in patients with stromal thinning and descemetoceles, or to reconstruct the anatomy of the eye, e.g. after corneal perforation.
- Therapeutic: To remove inflamed corneal tissue unresponsive to treatment by antibiotics or anti-virals.
- Cosmetic: To improve the appearance of patients with corneal scars that have given a whitish or opaque hue to the cornea.
Before A Keratoplasty Procedure
Once you and your eye doctor decide a cornea transplant is the best option for you, your name is placed on a list at a local eye bank. You may need to wait a few days to weeks for suitable tissue from a donor’s eye to become available for a corneal transplant.
Before a donor cornea is released for use in transplant surgery, it is checked for clarity and screened for the presence of any diseases such as hepatitis and AIDS, in accordance with the Eye Bank Association of India’s strict medical standards.
Only corneas that meet these stringent guidelines are used in corneal transplant surgery to ensure the health and safety of the graft recipient.
During A Corneal Transplant
Your eye surgeon will first administer either local or general anesthesia, depending on your health, age, eye injury or disease, and whether or not you prefer to be asleep during the procedure.
If local anesthesia is used, an injection is made into the skin around your eye to relax the muscles that control blinking and eye movements, and eye drops are used to numb your eye. You will be awake during the procedure and most people don’t report any discomfort.
After the anesthesia has taken effect, an instrument called a lid speculum is used to keep your eyelids open. Your surgeon then measures the affected corneal area to determine the size of the donor tissue needed.
Traditional corneal transplant surgery. During traditional corneal transplant surgery, or penetrating keratoplasty (PK), a circular button-shaped, full-thickness section of tissue is removed from the diseased or injured cornea using a surgical cutting instrument called a trephine. A matching “button” from the donor tissue is then positioned and sutured into place. The sutures (stitches) remain in place typically for a year or more after surgery. Lastly, a plastic shield is placed over your eye to protect it during healing.
Penetrating keratoplasty surgery generally takes one to two hours and most procedures are performed on an outpatient basis, meaning you can go home a short while after the surgery (though you will need someone to drive you home).
Endothelial keratoplasty. In the past decade, a newer version of corneal transplant surgery called endothelial keratoplasty (EK) has been introduced for certain corneal conditions.
Endothelial keratoplasty selectively replaces only the innermost layer of the cornea (endothelium) and leaves the overlying healthy corneal tissue intact. The endothelium controls the fluid balance in the cornea, and if it becomes damaged or diseased, this can cause significant corneal swelling and loss of vision.
In EK, the surgeon makes a tiny incision and places a thin disc of donor tissue containing a healthy endothelial cell layer on the back surface of your cornea. An air bubble is used to position the new endothelial layer into place. The small incision is self-sealing and typically no sutures are required.
Recovering From A Corneal Transplant
Total cornea transplant recovery time can be up to a year or longer. Initially, your vision will be blurry for the first few months — and in some cases may be worse than it was before — while your eye gets used to its new cornea.
As your vision improves, you gradually will be able to return to your normal daily activities. For the first several weeks, heavy exercise and lifting are prohibited. However, you should be able to return to work within a week after surgery, depending on your job and how quickly your vision improves.
Antibiotic drops, Steroid eye drops and if required few other medications will be prescribed for several months to help your body accept the new corneal graft, as well as other medications to help control infection, discomfort and swelling. You should keep your eye protected at all times by wearing a shield or a pair of eyeglasses so that nothing inadvertently bumps or enters your eye.
If stitches were used in your surgery, they usually are removed three to 17 months post-surgery, depending on the health of your eye and the rate of healing. Adjustments can be made to the sutures surrounding the new corneal tissue to help reduce the amount of astigmatism resulting from an irregular eye surface.
As with any type of surgery, always follow the instructions of your eye surgeon to help minimize corneal transplant complications and expedite healing.
Risks
Cornea transplant is a relatively safe procedure. Still, it does carry a small risk of serious complications, such as:
- Eye infection
- Increased risk of clouding of the eye’s lens (cataract)
- Pressure increase within the eyeball (glaucoma)
- Problems with the stitches used to secure the donor cornea
- Rejection of the donor cornea
- Swelling of the cornea
Vision After A Corneal Transplant
Your eyesight should gradually improve a few weeks after a corneal graft, but it could take anywhere from a couple of months up to a year to have a stable vision in the eye that receives the donor tissue.
You will be left with a degree of myopia (nearsightedness) and astigmatism because the curve of the new corneal tissue can’t match exactly the curve of your natural cornea.
Post-surgery refraction is somewhat unpredictable, and large amounts of astigmatism will still present a challenge when fitting those patients with glasses afterwards.
Mild refractive errors caused by corneal transplant surgery can be corrected with glasses; otherwise, contact lenses are required.
Rigid gas permeable contact lenses, also known as RGP or GP lenses, and hybrid contact lenses usually are the most suitable contacts for corneal transplant patients due to the irregularity of the cornea after transplant. However, soft contact lenses often are an option as well.
Because your vision will fluctuate during the first few months following your surgery, it is advisable to wait until your eye doctor tells you your vision is stable before you fill an eyeglass prescription or are fitted for contact lenses.
Corneal transplant at Shekar Eye Hospital
Corneal transplant surgery is done at Shekar Eye Hospital by experienced eye surgeons with utmost care and precautions. We procure high-quality graft tissues from standard Eye banks at the earliest and offer you the treatment. Consult our specialists for further details about the procedure.
