The cornea is the clear covering on the front of the eye. The cornea bends, or refracts, light rays so that they can focus on the retina in the back of the eye. In order to produce a clear image, a certain corneal curvature is required. An irregular corneal curvature may be surgically corrected with refractive surgery procedures.
Refractive surgery improves vision and reduces or eliminates the need for eyeglasses or contact lenses. A thorough medical eye examination and consultation are necessary before a treatment decision can be made.
The cornea is the clear covering of the front of the eye which bends, or refracts, light rays as they enter the eye. For clear vision to occur, the cornea must have the correct shape and clarity to focus incoming light rays precisely on the retina at the back of the eye. When the cornea becomes cloudy or misshapen from injury, infection or disease, transplantation may be recommended to replace it.
Types of Corneal Transplant Procedures
While a Corneal Transplant is considered safe for most patients, there are certain risks associated with any surgical procedure.
There are several different corneal transplant procedures available to help restore vision in patients with corneal problems. The traditional corneal transplant procedure involves replacing the entire damaged cornea with a healthy one from a human donor, which is usually obtained from an eye bank. Technological advances have allowed for the development of specialized procedures that replace only the damaged part of the cornea, while leaving the healthy parts intact.
- Penetrating keratoplasty is the traditional full-thickness corneal transplant
- Lamellar keratoplasty is a partial thickness corneal transplant
- Endothelial keratoplasty (DSAEK, DSEK or DMEK) is the removal of abnormal corneal tissue
Corneal transplants are usually performed with local anesthesia so there is no pain. During the procedure, the cornea is replaced with one from a human donor. The new cornea carries little risk of rejection and can last for many years.
Descemet's stripping endothelial keratoplasty, known as DSEK is a surgical procedure that removes the abnormal inner lining of the cornea, known as the endothelium, replacing it with a donor cornea.
Endothelial keratoplasty is performed through a much smaller incision than regular cornea transplantation resulting in a shorter recovery time and with fewer risks than a traditional corneal transplant. Recovery of vision is quicker with endothelial keratoplasty and there is less of a restriction on activities. There is less of an issue with astigmatism in an endothelial keratoplasty and there are minimal or no suture problems.
During the endothelial keratoplasty procedure, the surgeon will make an incision in the sclera, the white part of the eye. This incision allows the surgeon to access the cornea and remove the damaged endothelial tissue using a microkeratome blade, the same instrument that is used during LASIK surgery. The donor tissue is then folded and implanted inside the eye.
After the donor tissue has been placed, it will either unfold on its own or be unfolded by the surgeon. An air bubble is injected to properly position the graft. This procedure is performed with a topical anesthetic to minimizing any potential discomfort. The actual procedure takes up to 45 minutes to perform.
CK (Conductive Keratoplasty)
Conductive keratoplasty, also known as CK, is a non-laser, non-invasive procedure to correct low to moderate hyperopia with or without astigmatism. CK is also used to manage presbyopia, reducing the need for reading glasses. FDA approved, CK delivers radio-frequency energy to the outside edges of the cornea, causing the band of connective tissue around the cornea to tighten, steepening the cornea and improving near vision.
Candidates for CK
Patients eligible for the conductive keratoplasty procedure include the following:
- Over the age of 40
- Good vision
- Require reading glasses
- Stable vision for at least one year
- Healthy eyes
Patients not eligible for the conductive keratoplasty procedure include the following:
- Patients with a pacemaker
- Patients with severe dry eyes
- Patients who are pregnant or nursing
The CK Procedure
Performed in surgeons office with anesthetic eye drops. A probe, as thin as a strand of human hair, emits radio-frequency energy in a circular pattern, to the periphery of the cornea. The procedure takes a few minutes for each eye.
Risks and Complications of CK
- Feeling that something is in the eye
- Sensitivity to light
- Tearing of the eyes
- Over correction of vision
Presbyopia and hyperopia are progressive diseases. As patients age, eyes will continue to progress and change. CK is not a permanent solution to presbyopia or hyperopia.
As the first FDA approved method for treating hyperopia, CK is safer and less invasive than the LASIK procedure. It's quick -- less than three minutes per eye -- and uses a topical anesthetic. With minimal post-operative discomfort, return of vision is almost immediate.