Corneal transplantation involves replacing the damaged cornea with a healthy one from a donor (usually provided through an eye bank). We perform both traditional corneal transplant and endothelial transplant or DSAEK, which is a partial transplant of the cornea.
Corneal Transplantation and DSAEK
The human cornea is composed of five layers, the epithelial layer is the most superficial layer and lies on the second layer called Bowman's membrane. The third layer called the stroma is the thickest and makes up about 90% of the total corneal thickness. Descemet's membrane is the fourth layer and provides support for the innermost layer, the corneal endothelium. The endothelial cells pump fluid out of the cornea which is necessary for the cornea to remain clear and thin and provide good vision for the eye. If the pump cells become dysfunctional, damaged, or destroyed, the cornea becomes swollen and cloudy, and this causes blurry vision and pain.Endothelial cells can be lost due to aging, inherited diseases (such as Fuchs dystrophy), trauma, or previous intraocular surgery. If a critical number of endothelial cells are lost the cornea becomes swollen and cloudy. Severe cases require a corneal transplant.
Penetrating Keratoplasty: Traditional transplant
A penetrating keratoplasty (PKP) is a full-thickness corneal transplant, and was first developed over 100 years ago. In this procedure, donor tissue is transplanted to replace a patient's central cornea. A corneal transplant is done for a variety of conditions that lead to poor vision including those that affect all layers of the cornea. Traditional corneal transplant surgery has about a 90% success rate, and the rate of rejection is only about 8%. Rejection episodes can often be controlled with topical anti-inflammatory drops. Occasionally, there are problems with sutures which can come loose, cause infections, or cause astigmatism. The astigmatism after traditional corneal transplant surgery can be significant enough that eyeglasses alone won't give adequate vision. These patients may ultimately require contact lenses or additional surgery to reduce or eliminate the astigmatism. Because the wound is full-thickness and 360 degrees, the corneal transplant wound is not as strong as normal. It is at risk to rupture or break open from mild or incidental trauma, even several years after the surgery. Full visual recovery can take over 12 months.
Endothelial Transplant (DSAEK)
A DSAEK procedure is a partial-thickness corneal transplant that replaces only the endothelial layer. A thin piece of donor tissue containing only the endothelial cell layer is inserted onto the back surface of the patient's cornea. The surgery itself takes less time with an experienced surgeon, involves a smaller surgical incision, requires far fewer stitches, heals faster and more reliably, and the vision returns faster.There are several advantages to the DSAEK operation compared to standard corneal transplant surgery. The smaller wound is more stable and less likely to break open from trauma. Because the wound is smaller and requires far fewer sutures, there is very little postoperative astigmatism which can delay the visual recovery. The maximum return in vision takes only about 3 to 4 months following DSAEK. Only patients with endothelial cell problems are candidates for DSAEK. Patients with corneal scarring or other conditions affecting other layers of the cornea will still require the full-thickness procedure. Since corneal specialists have only been performing DSAEK for a few years, there are limited long-term follow-up studies. There is a risk of the thin button of endothelium becoming displaced within the first few days or weeks after surgery and requiring a return trip to the operating room to reposition it. If the DSAEK operation fails, the operation can be repeated with another button of donor endothelium. If the DSAEK fails, either after one or multiple attempts, a traditional corneal transplant operation (PKP) can be performed without any obvious disadvantages.It is the latest technique that offers a much quicker recovery and visual rehabilitation. Both are outpatient procedures that require local anesthesia. These are the most common type of transplant surgeries and have very high success rates.