Glaucoma is often characterized by decreased pressure-sensitive aqueous outflow through the trabecular meshwork. This defect in pressure-sensitive aqueous outflow is evident from the low tonographic facility of outflow ("C") measured in many patients. The impairment in outflow facility causes the high intraocular pressure (IOP) and large diurnal IOP fluctuations often found in glaucoma. Because large diurnal IOP fluctuations have been shown to be a risk factor for glaucomatous progression, IOP-lowering therapy should aim to achieve a low, stable IOP. Pressure-sensitive aqueous outflow helps prevent and dampen pressure spikes; thus, drugs that enhance outflow facility, in particular, may stabilize as well as lower IOP. Outflow facility is an attractive target for glaucoma treatment because enhancing outflow facility tends to restore the self-regulating tendency of IOP. Older drugs such as the cholinergic pilocarpine and the catecholamine epinephrine act primarily by improving outflow facility. This action is also important for the recently introduced prostamide, bimatoprost, as well as for the prostaglandin prodrug, latanoprost. Realization of the importance of facility of outflow in lowering and stabilizing IOP will stimulate additional research into the mechanism of action of ocular hypotensive agents and will help optimize the medical treatment of glaucoma.
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http://dx.doi.org/10.1016/s0039-6257(03)00003-1 | DOI Listing |
JCI Insight
January 2025
Gavin Herbert Eye Institute-Center for Translational Vision Research, Depar, University of California Irvine School of Medicine, Irvine, United States of America.
Elevation of intraocular pressure (IOP) due to trabecular meshwork (TM) dysfunction, leading to neurodegeneration, is the pathological hallmark of primary open-angle glaucoma (POAG). Impaired axonal transport is an early and critical feature of glaucomatous neurodegeneration. However, a robust mouse model that accurately replicates these human POAG features has been lacking.
View Article and Find Full Text PDFInvest Ophthalmol Vis Sci
December 2024
Department of Ophthalmology, Duke University, Durham, North Carolina, United States.
Intraocular pressure (IOP) elevation is the primary risk factor and currently the main treatable factor for progression of glaucomatous optic neuropathy. In addition to direct clinical and living animal in vivo studies, ex vivo perfusion of anterior segments and whole eyes is a key technique for studying conventional outflow function as it is responsible for IOP regulation. We present well-tested experimental details, protocols, considerations, advantages, and limitations of several ex vivo model systems for studying IOP regulation.
View Article and Find Full Text PDFInquiry
November 2024
Kyung Hee University, Seoul, Republic of Korea.
This study analyzes hospital bed capacity and resource allocation using inflow and outflow indices to identify disparities in bed utilization. The COVID-19 pandemic highlighted the need for effective healthcare management, particularly in the allocation of specialized beds such as those in intensive care units (ICU). Despite a high bed-to-population ratio, South Korea faces regional disparities in bed distribution, especially in Seoul, which accounts for 12.
View Article and Find Full Text PDFSci Rep
November 2024
Solar Physics Laboratory, NASA/GSFC, Mail Code 671, Greenbelt, MD, 20771, USA.
The solar wind is a continual outflow of plasma and magnetic field from the Sun's upper atmosphere-the corona-that expands to fills the solar system. Variability in the near-Earth solar-wind conditions can produce adverse space weather that impacts ground- and space-based technologies. Consequently, numerical fluid models of the solar wind are used to forecast conditions a few days ahead.
View Article and Find Full Text PDFPharmaceuticals (Basel)
September 2024
Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Texas Southern University, Houston, TX 77004, USA.
Background: Hydrogen sulfide (HS)-releasing compounds can reduce intraocular pressure in normotensive rabbits by increasing aqueous humor (AH) outflow through the trabecular meshwork. In the present study, we investigated the contribution of endogenous HS and the role of intramurally generated prostaglandins in the observed increase in AH outflow facility in an ex vivo porcine ocular anterior segment model.
Material And Methods: Porcine ocular anterior segment explants were perfused with Dulbecco's Modified Eagle's Medium maintained at 37 °C and gassed with 5% CO and 95% air under an elevated pressure of 15 mmHg for four hours.
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