An advanced corneal transplant technique that requires no complete cuts to the cornea, needs no sutures and improves vision in a matter of weeks rather than months to a year is being performed successfully at Advocate Christ Medical Center in Oak Lawn, Ill.
Called DMEK or Descemet membrane endothelial keratoplasty, the procedure involves removing only the damaged portion of a person's cornea and replacing it with a very thin sliver of tissue from a healthy donor cornea. An air bubble holds the donor cells in place and allows them to reconstruct the damaged area of the cornea, explained Thomas John MD, an ophthalmologist and corneal/refractive surgeon at Christ Medical Center, who is one of only a handful of eye surgeons in the country performing DMEK.
"Essentially, this new technique is akin to a 'saran wrap' corneal transplant. We are removing the damaged corneal cells from the patient's eye and replacing them with a thin wrap of healthy cells taken from the innermost lining (endothelium) of the donor cornea," Dr. John said. The endothelium is what directs the transport of fluid across the back surface of the cornea and is responsible for keeping the cornea clear.
Unlike traditional transplantation in which a large part of the cornea is removed and donor corneal tissue is stitched into the eye, the new approach allows the patient to retain his or her own cornea without complete, circular corneal cuts; without corneal sutures; with little risk of infection; and with a more rapid return of improved vision, Dr. John said.
"Instead of waiting months to experience enhanced vision, patients who have undergone this highly advanced approach are seeing better in a matter of a few weeks, without the kind of astigmatism that can occur following a standard cornea transplant," he said. Irregular curvature of the cornea can cause astigmatism, a condition in which vision is blurred because of the inability of the eye's optics to create a sharp, focused image on the retina.
Also significant are the apparent longer-term benefits of selective tissue corneal transplantation or STCT, a term Dr. John coined in a professional journal editorial. Because patients who undergo the new procedure retain their own corneas without circular cuts to the cornea, they have no risk of rupturing the cornea should the eye later be bumped or otherwise traumatized, no astigmatism from the procedure, and no risk of corneal sutures breaking over time or suture-related, serious eye infections. Spontaneous breaking of corneal sutures may result in a mini-eye emergency, Dr. John said.
The cornea is the clear front window of the eye, transmitting light to the eye's interior and allowing clear vision. Corneal diseases, which are not uncommon and often painful, can cause clouding and distortion of the cornea and may lead to blindness. Eye infections, certain eye conditions like Fuchs' corneal dystrophy, trauma, cataract surgery, advancing age, heredity, and even use of contact lenses can affect the cornea. When corneal diseases reach an advanced stage with loss of corneal clarity, corneal transplantation is usually necessary to restore vision.
"For patients who need corneal transplantation, the selective tissue approach truly can be life changing," said Dr. John.