Researchers have identified an important cause of why secondary corneal transplants are rejected at triple the rate of first-time corneal transplants.
The cornea - the most frequently transplanted solid tissue - has a first-time transplantation success rate of about 90 percent. But second corneal transplants undergo a rejection rate three times that of first transplants.
More than 40,000 transplants are performed annually to replace the cornea, the clear outer lens at the front of the eye, with tissue from a donor. Most corneal transplants are done to correct severe visual impairments caused by keratoconus, a condition in which the normally dome-shaped cornea progressively thins and becomes cone-shaped, according to the American Academy of Ophthalmology.