Why is tissue typing unnecessary in corneal transplant?

Unlike other solid organ transplants such as kidney or heart, tissue typing is not necessary for cornea transplantation. This is because the cornea, unlike other organs such as the heart or liver, is an immune-privileged tissue. This means it does not readily elicit an immune response from the recipient's immune system.

The absence of blood vessels in the cornea and the unique composition of its cellular and extracellular components contribute to its immune-privileged nature. Consequently, the risk of immune rejection is significantly lower in corneal transplants compared to other solid organ transplants.

Additionally, the cornea primarily functions as a protective covering for the eye and does not have a vital role in overall bodily functions. Hence, the immune response to a corneal graft, even if it occurs, is usually milder and more localized, allowing for better graft survival without extensive tissue matching or immunosuppressive medications.