Abstract
Aging is one major risk factor for development of primary open-angle glaucoma (POAG). It is assumed that preexisting age-related changes of the trabecular meshwork (TM) play a role for the development of increased outflow resistance and intraocular pressure (IOP) in various types of glaucoma. These age-related changes in the TM develop concomitantly with presbyopia. Therefore, the functional relationship between ciliary muscle (CM) and TM and the age-related changes in morphology of the outflow system are described first. One main finding in the aging TM concerns changes of the elastic fiber network and the anterior elastic tendons of the CM. There is an increase in thickness of the sheath of the elastic fibers. Cross-sections through these fibers with their sheath appear as extracellular plaques and were therefore termed “sheath derived plaques” (SD-plaques). Morphologically, the TM changes in POAG resemble that of the aging TM, but in POAG there is a significant increase in SD-plaques compared to age-matched controls. This increase is due to fine fibrils and other components of the extracellular material (ECM) that adhere to the sheaths of the elastic fibers and their connections to the inner wall endothelium. In POAG eyes there is also a marked loss of TMcells, at places leading to fusion and thickening of trabecular lamellae.
Published Version
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