Lymphatic System in the Eye

Almost simultaneously with the description of the blood circulation in the seventeenth century, the lymphatic system was first characterized. However, lymphatics have endured centuries of ignorance in comparison to blood vessels, which have been the subject of extensive prior research. Lymphatics are not as obvious as blood arteries. The lymphatic network is anatomically different from the blood circulation network in two ways: (1) it is a unidirectional channel instead of a circuit; and (2) lymphatic capillaries lack pericytes, tight junctions, and a continuous basement membrane, leaving significant interendothelial gaps. Immunity and the equilibrium of tissue fluid in the body depend on lymphatic function. Additionally, a growing body of research demonstrates the significance of lymphangiogenesis in the etiology of illnesses such as inflammation and tumor metastasis. With the exception of the conjunctiva, it was previously believed that the eye lacked lymphatic vessels. Nevertheless, developments in the field, such as the discovery of lymphatic endothelial markers (like lymphatic endothelial hyaluronan receptor-1 [LYVE-1] or podoplanin) and lymphangiogenic factors (like vascular endothelial growth factor [VEGF]-C), have demonstrated the existence and potential functions of lymphatics and lymphangiogenesis in the eye. According to recent research, there are lymphatic vessels in the corneal limbus, ciliary body, lacrimal gland, orbital meninges, and extraocular muscles. There may also be a lymphatic-like system in the choroid. The maintenance of interstitial fluid equilibrium, immune cell trafficking, lipid absorption, tumor growth, and metastasis are all significantly impacted by lymphatic vessels. The lymphatic vasculature has recently developed new functional tasks that may be connected to pathological circumstances. Gaining further knowledge about lymphatics and lymphangiogenesis in the eye will lead to new therapeutic approaches for ocular illnesses that avoid vision loss.