Consensus Statement on the immunohistochemical detection of ocular lymphatic vessels

The eye is an immune-privileged site where foreign tissue grafts enjoy long-term or even indefinite survival in the absence of immunosuppressive treatments. A number of factors contribute to the immune privileged nature of various sites within the eye including the absence of a “classical” ocular lymphatic system. Recent advances in lymphangiogenesis research 3, have however, shown that lymphangiogenesis can occur in the normally avascular and alymphatic cornea in inflammatory conditions and intraocularly, if the scleral border is compromised. To date, the evidence for a “classical” lymphatic system in the inner portions of the eye under physiological conditions remains controversial.Given the recent and ever increasing interest in the role of ocular lymphatic vessels in the normal eye and their role in the pathogenesis of corneal graft rejection, ocular tumor recurrence and metastasis, dry eye, allergy, and glaucoma and along with the hope for new anti-lymphangiogenic or pro-lymphangiogenic treatment concepts for these diseases, it is essential to develop evidence-based guidelines on the criteria for identifying ocular lymphatic vessels.