A corneal transplant, or keratoplasty, is a surgical procedure that replaces damaged or diseased corneal tissue with healthy tissue from a deceased human donor. The cornea is the transparent, dome-shaped front part of the eye that allows light to enter and focus, making clear vision possible. When the cornea becomes scarred, swollen, or changes shape due to conditions like keratoconus, Fuchs’ dystrophy, or severe infections, vision can become impaired or lost. The primary goal of a corneal transplant is to restore vision, alleviate discomfort, and enhance a person’s quality of life.
The Possibility of Repeat Corneal Transplants
More than one corneal transplant is often possible if the initial procedure does not yield the desired long-term outcome. While the first transplant offers the highest success rates, subsequent procedures can be performed. Repeat transplants may be needed due to graft rejection, the most common reason, or other complications like infection, trauma, or recurrence of the underlying corneal disease.
Individuals may undergo one, two, or even more repeat transplants, though each situation is evaluated individually by ophthalmologists. If vision loss is solely due to the cornea, a subsequent transplant can help restore sight. The median time between the initial transplant and the first repeat procedure is around 25 months, with similar intervals for subsequent transplants.
Factors Affecting Eligibility for Subsequent Transplants
Ophthalmologists consider several factors when evaluating patients for additional corneal transplants, as these procedures become more complex. The overall health of the eye is a significant consideration, including the retina, optic nerve, and intraocular pressure. Pre-existing conditions like glaucoma or inflammation can increase the risk of graft failure.
Understanding the reason for previous graft failure is important for planning. Common causes include chronic graft rejection, endothelial dysfunction, infection, or the original disease returning. Other factors influencing eligibility include:
The type of previous transplant (e.g., full-thickness PK or partial-thickness DSEK/DMEK) influences the approach for repeat surgery.
Patient compliance with post-operative medication, especially immunosuppressants, and attendance at follow-up appointments, which are crucial for preventing rejection and ensuring healing.
The availability of suitable donor tissue, as all corneal transplants rely on healthy tissue from deceased donors.
A careful risk-benefit analysis, weighing potential vision improvement against the increased risks of repeat procedures.
Outcomes and Challenges of Repeat Procedures
Repeat corneal transplants have lower success rates than initial procedures, and success likelihood decreases with each subsequent transplant. For example, a first full-thickness transplant for a low-risk condition like keratoconus might have a 95% survival rate at four years, but this can drop to 86% for a second, 71% for a third, and 56% for a fourth or subsequent transplant. This trend is due to increased risk factors that accumulate with each surgery.
Heightened risks include a greater chance of graft rejection, the most common cause of failure in repeat cases. There is also an increased likelihood of developing or worsening glaucoma, characterized by elevated intraocular pressure that can damage the optic nerve. Other complications include a higher risk of infection and more severe astigmatism, which can significantly affect visual clarity.
Post-operative healing can be slower and more complicated in repeat procedures, necessitating diligent long-term care. This includes extended use of immunosuppressive eye drops to prevent rejection and frequent follow-up appointments to monitor graft health and manage complications. While vision improvement is the goal, the degree of improvement can be more variable and less predictable with repeat procedures.