A corneal transplant is a surgical procedure that replaces damaged or diseased corneal tissue with healthy tissue from a donor. This intervention aims to restore vision by improving the clarity and function of the eye’s outer layer. While generally successful, a potential complication following this surgery is corneal transplant rejection, which occurs when the recipient’s immune system identifies the new corneal tissue as foreign. Understanding the visual signs of this rejection and knowing the appropriate steps to take can significantly influence the outcome.
Understanding Corneal Transplant Rejection
Corneal transplant rejection occurs when the body’s immune system identifies the donor cornea as foreign and attacks it, similar to how it fights infections. While the cornea is considered an “immune-privileged” site, meaning it has a reduced tendency to provoke an immune response due to its lack of blood vessels and lymphatic drainage, rejection can still occur.
The immune response involves both innate and adaptive immunity. Approximately 18% to 21% of corneal graft recipients experience some form of rejection. This complication is the most common cause of corneal graft failure in the period after surgery.
How to Identify Rejection Visually
Identifying corneal transplant rejection often involves observing specific changes in the eye and experiencing certain symptoms. One common sign is increased redness around the eye, which may appear more pronounced than typical post-surgical irritation. Patients might also report new or worsening pain or discomfort.
Another frequent symptom is increased sensitivity to light, known as photophobia. Vision changes are also a significant indicator, often presenting as cloudiness or haziness. The cornea itself may appear hazy or opaque, indicating swelling. In some instances, subtle white spots or infiltrates may become visible on the corneal surface, or a distinct line might appear, signaling an immune reaction.
Different Forms of Rejection
Corneal transplant rejection can manifest in various forms, depending on which layer of the cornea is primarily affected by the immune response. Epithelial rejection involves the outermost layer of the cornea. This type often appears as a distinct, elevated line or pattern of white cells on the surface of the graft.
Stromal rejection affects the middle layer of the cornea. This leads to a noticeable haze or cloudiness within the corneal tissue, caused by swelling. Endothelial rejection is the most frequent and most serious form, accounting for about 50% of rejection episodes. This type targets the innermost layer, which is responsible for maintaining the cornea’s clarity by pumping out fluid. Signs of endothelial rejection include keratic precipitates, which are small deposits of inflammatory cells on the back surface of the cornea, and a visible line of inflammatory cells known as a Khodadoust line that migrates across the cornea.
What to Do About Rejection
If corneal transplant rejection is suspected, immediate medical attention is important. Contacting the ophthalmologist or transplant specialist is important, as early intervention can significantly improve the chances of successfully reversing the rejection episode. Diagnosis involves a thorough eye examination, often utilizing a slit lamp to observe the specific changes in the corneal layers.
Treatment for rejection primarily involves the use of corticosteroids, which work to suppress the immune system’s response. These medications can be administered as eye drops, oral tablets, or injections, depending on the severity of the rejection. In cases of severe or recurrent rejection, other immunosuppressive medications might be considered. With timely and appropriate treatment, reversal rates for rejection range from 50% to 90%. Adherence to prescribed medications and regular follow-up appointments are also important for maintaining graft health and preventing future episodes.