THE ELEMENTS OF INTRAOCULAR FLUID LYMPHATIC OUTFLOW PATHWAYS IN CHOROID IN NORM AND IN GLAUCOMA PATIENTS

Abstract

Purpose. To detect and study the structure of aqueous humor lymphatic outflow pathways in choroid in normotensive patients and patients with primary open-angle glaucoma (POAG).Material and methods. Choroid fragments of seven human eyes (including two eyes with terminal glaucoma) enucleated on medical indications were studied. The structure of the choroid was investigated using immunohistochemistry and electron microscopy.Results. Lymphatic channels and lymphatic lacunae were revealed in the choroid structure. Lymphatic channels were detected in choriocapillar and vascular layers and were limited by Podoplanin+, Prox-1+, LYVE-1+ endothelium-like cells, fibroblasts and pigment cells. Lymphatic lacunae were located in suprachoroid layer and covered with endothelium-like cells and fibroblasts. Morphometric study showed an increase of the volume density of epithelium, interstitial spaces and choroid vessels related to edema and swelling of the choroidal stroma in the terminal stage of glaucoma.Conclusions. Human choroid contains lymphatic structures that are probably a part of the ocular lymphatic drainage system and participate in the aqueous humor outflow. Choroidal edema and swelling, the increase of the volume density of epithelium, interstitial spaces and choroid vessels in the terminal POAG stage indicate the lymphatic drainage dysfunction beginning from initial stages of glaucoma and lead to an aqueous humor outflow alteration through the protective lymphatic system.

Keywords

• prelymphatics
• the organ-specific lymphatic capillaries
• choroid