How many aqueous humor outflow pathways are there?
Costagliola Ciro, dell'Omo Roberto, Agnifili Luca, Bartollino Silvia, Fea Antonio M, Uva Maurizio G, Zeppa Lucio, Mastropasqua Leonardo
AI Summary
This review explores conventional, uveoscleral, and newly identified uveolymphatic aqueous humor outflow pathways. It finds these adaptive routes are crucial for IOP regulation, suggesting new glaucoma therapies by targeting them.
Abstract
The aqueous humor (AH) outflow pathways definition is still matter of intense debate. To date, the differentiation between conventional (trabecular meshwork) and unconventional (uveoscleral) pathways is widely accepted, distinguishing the different impact of the intraocular pressure on the AH outflow rate. Although the conventional route is recognized to host the main sites for intraocular pressure regulation, the unconventional pathway, with its great potential for AH resorption, seems to act as a sort of relief valve, especially when the trabecular resistance rises. Recent evidence demonstrates the presence of lymphatic channels in the eye and proposes that they may participate in the overall AH drainage and intraocular pressure regulation, in a presumably adaptive fashion. For this reason, the uveolymphatic route is increasingly thought to play an important role in the ocular hydrodynamic system physiology. As a result of the unconventional pathway characteristics, hydrodynamic disorders do not develop until the adaptive routes cannot successfully counterbalance the increased AH outflow resistance. When their adaptive mechanisms fail, glaucoma occurs. Our review deals with the standard and newly discovered AH outflow routes, with particular attention to the importance they may have in opening new therapeutic strategies in the treatment of ocular hypertension and glaucoma.
MeSH Terms
Shields Classification
Key Concepts6
Recent evidence demonstrates the presence of lymphatic channels in the eye and proposes that they may participate in overall aqueous humor (AH) drainage and intraocular pressure regulation, in a presumably adaptive fashion.
The uveolymphatic route is increasingly thought to play an important role in the ocular hydrodynamic system physiology.
Hydrodynamic disorders do not develop until the adaptive routes (aqueous humor outflow pathways) cannot successfully counterbalance increased aqueous humor outflow resistance; when their adaptive mechanisms fail, glaucoma occurs.
The conventional (trabecular meshwork) and unconventional (uveoscleral) pathways are widely accepted distinctions for aqueous humor (AH) outflow, differentiating the impact of intraocular pressure on AH outflow rate.
The conventional route (trabecular meshwork) is recognized to host the main sites for intraocular pressure regulation.
The unconventional pathway (uveoscleral pathway), with its great potential for aqueous humor (AH) resorption, seems to act as a relief valve, especially when trabecular resistance rises.
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