New insights into aqueous humor outflow system and ophthalmic lymphatic drainage pathway

Authors: Liu Yameng,  Pan Xiaojing
DOI: 10.3760/cma.j.cn115989-20190820-00358
Published 2022-04-10
Cite asChin J Exp Ophthalmol, 2022, 40(4): 361-365.

Abstract

Glaucoma is the first irreversible blinding eye disease in the world, and vision loss due to glaucoma is related to the obstruction of the aqueous humor drainage channel, which leads to increased intraocular pressure and damage to the optic nerve.The relationship between the ocular lymphatic system and the aqueous humor drainage pathway is of important significance.Exploration of the generation and development of ocular lymphatic vessels and identification of the markers of ocular lymphatic vessels (LVs) are important for researching whether lymphatic pathways are involved in the aqueous humor outflow in glaucoma.Relationship between aqueous humor drainage system and ocular lymphatic drainage pathway can be elucidated from following aspects: (1)podoplanin is highly expressed in trabecular meshwork endothelial cells, while no expression of platelet-endothelial cell adhesion molecule (CD31) is found, suggesting that there is a close relationship between trabecular meshwork and LVs; (2)there are similarities in morphology, molecules and function between Schlemm canal and LVs, and Schlemm canal not only has some characteristics of LVs and blood vessels, but also some undiscovered characteristics of blood vessels and lymphatic endothelial cells; (3)the bulbar conjunctiva is rich in LVs, suggesting that the bulbar conjunctiva has active tissue drainage and immunoregulatory functions; (4)the sclera is mainly composed of collagen fibers and lacks real LVs, but many lymphatic vessel endothelial hyaluronic acid receptor 1 (LYVE-1)-positive macrophages around the scleral vessels are regulated by tissue-specific factors; (5)multiple lymphatic markers can be detected in ciliary body, and suspected LVs can be observed by electron microscopy; (6)various lymphatic markers can be expressed in a single choroidal cell, with LYVE-1 expressed highest.Research progress in the lymphatic system of LVs, lymphatic markers, and aqueous humor outflow was reviewed in this article.

Key words:

Eye; Aqueous humor; Drainage; Lymphatic vessels

Contributor Information

Liu Yameng

State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University &

Shandong Academy of Medical Sciences, Qingdao Eye Hospital of Shandong First Medical University, Qingdao 266071, China

Pan Xiaojing

State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University &

Shandong Academy of Medical Sciences, Qingdao Eye Hospital of Shandong First Medical University, Qingdao 266071, China

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