What is Keratoplasty?
Keratoplasty is the medical term for a corneal transplant surgery. During the keratoplasty procedure, the cornea is removed and replaced with tissue from a donor’s cornea. Keratoplasty is performed by an ophthalmologist who specializes in corneal disease. The cornea is the dome-shaped, transparent surface of the eye. Keratoplasty is only recommended for severe conditions that do not respond well to other lines of treatment. A keratoplasty may be required due to corneal degeneration, scarring, infection, or thinning.
There are various types of keratoplasty, including PK (penetrating keratoplasty), DALK (deep anterior lamellar keratoplasty), DSEK (Descemet’s stripping endothelial keratoplasty), DMEK (Descemet’s membrane endothelial keratoplasty), and CK (conductive keratoplasty). Each of these surgeries removes different layers of the cornea. Keratoplasty can benefit people who have severely reduced vision and very scarred corneas. However, there are surgical risks such as graft rejection and endophthalmitis.
- Keratoplasty is defined as a corneal transplant surgical procedure.
- Keratoplasty is done when the cornea is very damaged and needs to be replaced for conditions such as corneal dystrophies or corneal scarring.
- Keratoplasty has a moderate risk of corneal transplant rejection, in which the immune system attacks the donated cornea.
Keratoplasty refers to a corneal transplant surgery. The tissue used for the corneal transplant comes from a deceased human who donates their organs, including the corneal tissue. Corneal tissue is a universal donor, meaning that it can be transplanted into people of all blood types. Unlike organ transplants, corneal transplants do not need to be matched by blood type. Keratoplasty, or corneal transplant surgery, has one of the lowest risks of transplant rejection compared to other organ transplant surgeries. However, the risk of corneal transplant rejection still exists. There are many different types of keratoplasty surgeries:
- Penetrating Keratoplasty (PK)
Penetrating keratoplasty is a full-thickness cornea transplant. It removes all of the layers of the cornea, from the epithelium to the endothelium. All corneal layers are replaced with donor corneal tissue. Sutures are used to stitch the new cornea into place. Penetrating keratoplasty is the oldest technique of keratoplasty. It is more invasive than the other keratoplasty methods and has a higher risk of transplant rejection. Visual recovery is slow with a penetrating keratoplasty. It is done for conditions such as keratoconus, an eye disease that causes progressive weakening and thinning of the cornea.
- Deep Anterior Lamellar Keratoplasty (DALK)
Deep anterior lamellar keratoplasty removes the outermost layers of the cornea. Deep anterior lamellar keratoplasty removes two layers: stroma and Descemet’s membrane. The endothelium, the back layer of the cornea, is kept in place. DALK has the lowest risk of corneal transplant rejection out of all keratoplasty procedures because it does not replace the endothelium. DALK is a difficult surgery to perform and has more risk of breaking through the corneal tissues.
- Descemet’s Stripping Endothelial Keratoplasty (DSEK)
Descemet’s stripping endothelial keratoplasty is the most widely used keratoplasty technique. It removes and replaces three corneal layers: stroma, Descemet’s membrane, and endothelium. These are the innermost layers of the cornea. Only a small amount of stroma is removed. Because the stroma is removed and replaced, this surgery is more likely to cause postoperative corneal swelling. Descemet’s stripping endothelial keratoplasty is commonly used to treat Fuchs endothelial dystrophy.
- Descemet’s Membrane Endothelial Keratoplasty (DMEK)
Descemet’s membrane endothelial keratoplasty removes the two innermost layers of the cornea: Descemet’s membrane and endothelium. The stroma is not removed with DMEK. DMEK is less common than DSEK.
- Conductive Keratoplasty (CK)
Conductive keratoplasty is a type of refractive surgery that corrects the refractive error, similar to LASIK and PRK (photorefractive keratectomy). Conductive keratoplasty reshapes the cornea without removing any tissue. This procedure uses heat from radio waves to shrink the cornea’s collagen fibers. It is used to correct low farsightedness (less than +3.00 D). Conductive keratoplasty is not a corneal transplant surgery. It is only a refractive surgery that fixes the power of the eye so no glasses need to be worn afterward.
Symptoms of Cornea Rejection
Approximately 10% of corneal transplants are rejected by the host. The corneal transplant is rejected when the body’s immune system attacks the donor cornea mistakenly. Incidence of graft rejection is greatest in the first year following the transplant. Corneal transplant rejection requires medical treatment or sometimes an additional cornea transplant.
Symptoms of corneal transplant rejection include:
- Eye pain
- Eye redness
- Loss of vision
- Light sensitivity
Pre- and Post-Keratoplasty Process
Before Keratoplasty, you must undergo the following:
- Thorough eye exam: The doctor looks for conditions that can create complications post-surgery.
- Eye measurements: The eye doctor measures the size of the cornea required for the best match.
- Reviewing medications: The patient can be asked to stop certain medications or supplements before keratoplasty.
- Treatment for other eye issues: Unrelated eye issues such as inflammation or infection can decrease the chances of a successful keratoplasty. The eye doctor usually treats such problems first before carrying out the procedure.
After the keratoplasty procedure, a combination of eye drops are prescribed. Eye drops must be put into the eye multiple times a day. It is important to strictly follow the regimen of eye drops recommended by the doctor to avoid any infection or complications after the surgery. An anti-inflammatory (steroid) eye drop and an antibiotic eye drop are prescribed. The eye drops may need to be taken for up to a year after the keratoplasty.
Risks Of Keratoplasty
Keratoplasty is usually safe, but always has risks. The complications that may occur after keratoplasty are:
- Endophthalmitis: a rare but severe eye infection
- Issues with stitches used to secure the cornea
- Rejection of the donor cornea
- Hazy vision
- Retinal detachment