A cornea transplant involves replacing damaged or diseased corneal tissue with healthy donor tissue. This procedure, also known as keratoplasty, aims to restore vision or alleviate pain. While often successful, a potential complication is the body’s immune response identifying the transplanted tissue as foreign, leading to rejection.
Understanding Cornea Transplant Rejection
Cornea transplant rejection occurs when the recipient’s immune system recognizes the transplanted corneal tissue as foreign and mounts an attack against it. Despite the cornea being considered an “immune privileged” site due to its lack of blood vessels and lymphatic drainage, this privilege is not absolute, and rejection can still happen.
Different types of rejection can affect specific layers of the cornea. Epithelial rejection involves the outermost layer, presenting as a linear opacity or irregular surface. While often self-limited, it can sometimes precede more severe forms of rejection.
Subepithelial rejection, which is less common, manifests as deeper infiltrates within the corneal tissue. These can appear similar to those seen in certain viral infections and are caused by immune cells attacking stromal keratocytes.
Endothelial rejection is the most common and often the most serious type of rejection, accounting for about 50% of rejection episodes. It targets the innermost layer of the cornea, the endothelium, which is responsible for maintaining corneal clarity by pumping out fluid. Damage to these cells can lead to corneal swelling and cloudiness. If not treated promptly, endothelial rejection can result in irreversible damage and graft failure, where the transplanted cornea becomes permanently cloudy.
Recognizing the Signs
Patients may experience a decrease in visual clarity or blurred vision. The eye might also become noticeably redder. Patients may also experience increased eye pain or discomfort, heightened sensitivity to light, or visible changes like cloudiness or haze in the transplanted cornea. Sometimes, specific patterns like a “Khodadoust line,” which is a line of inflammatory cells on the inner surface of the cornea, or an epithelial rejection line, may be observed by an eye care professional. If any of these signs appear, seeking prompt medical attention from an ophthalmologist is important.
Managing Rejection
If cornea transplant rejection is suspected, an ophthalmologist performs a thorough eye examination to assess the transplanted cornea and determine the type and severity of the rejection. Early diagnosis increases the likelihood of successful treatment and graft preservation.
Corticosteroids are the primary treatment for cornea transplant rejection, suppressing the immune response and reducing inflammation. These medications can be administered in various forms.
Topical eye drops, such as prednisolone acetate 1% or dexamethasone, are frequently prescribed, often at a high frequency initially, such as hourly. For more severe cases, or if topical treatments are insufficient, oral corticosteroids like prednisone may be used. In some instances, particularly for severe endothelial rejection, intravenous corticosteroids such as methylprednisolone might be given as a pulse therapy. The goal of this intensive treatment is to quickly suppress the immune attack, reverse the rejection, and preserve the clarity and function of the transplanted cornea.
Beyond corticosteroids, other immunosuppressant medications may be considered, especially for high-risk patients or those who do not respond well to steroids. These include topical or oral forms of cyclosporine or tacrolimus, which target specific parts of the immune system. Adherence to the prescribed treatment regimen is important for long-term graft survival. If rejection is severe and unresponsive to treatment, or if the graft has failed, a repeat cornea transplant may be considered, though subsequent transplants can have a higher risk of rejection.
Reducing the Risk
Several measures can help minimize the likelihood of cornea transplant rejection. While not as extensively matched as other organ transplants, careful consideration of donor and recipient factors can play a role. Lifelong adherence to prescribed anti-rejection medications, often topical eye drops, is a primary proactive step. These medications continuously modulate the immune system’s response to the donor tissue.
Regular follow-up appointments with the ophthalmologist are also important. These visits allow monitoring of graft health, early detection of rejection, and medication adjustments. Certain lifestyle factors can also influence the risk of rejection. Avoiding eye injuries and promptly addressing infections can prevent inflammation that might trigger an immune response.