Glaucoma pathophysiology
|
Glaucoma Microchapters |
|
Diagnosis |
|---|
|
Treatment |
|
Case Studies |
|
Glaucoma pathophysiology On the Web |
|
American Roentgen Ray Society Images of Glaucoma pathophysiology |
|
Risk calculators and risk factors for Glaucoma pathophysiology |
Please help WikiDoc by adding more content here. It's easy! Click here to learn about editing.
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Rohan Bir Singh, M.B.B.S.[2]
Pathophysiology
The underlying pathogenesis of glaucoma is attributed to retinal ganglion cell death due to elevated level of intraocular pressure. The intraocular pressure is determined by the balance between secretion of aqueous humor by the ciliary body and its drainage through the two pathways i.e. the trabecular meshwork and uveoscleral outflow pathway.
Primary Open Angle Glaucoma
An elevated IOP can lead to damage the optic nerve head via induced mechanical changes at the lamina cribrosa, or via vascular dysfunction and resultant ischemia.[1] Multiple underlying mechanisms can result in elevated IOP, usually as a consequence of reduced aqueous outflow. These structural changes include:
- Outflow reduction due to obstruction of the trabecular meshwork by a foreign material such as glycosaminoglycans, red blood cells.
- Trabecular beams fusing due to endothelial cell loss.
- Phagocytic activity leading to endothelial cell loss.
- Loss of giant vacuoles from Schlemm’s canal endothelium.
- Reduction of Schlemm’s canal pore size.
Angle Closure Glaucoma
The angle-closure glaucoma occurs as a result of an obstruction in access to the drainage pathways. Typically, apposition or adhesion of the peripheral iris to the trabecular meshwork causes such an obstruction. The portion of the anterior chamber angle affected by such apposition is “closed,” and drainage of aqueous humor through the angle is prohibited.[2] The angle closure due to peripheral iris can either be appositional (transient obstruction) or synechial (permanent obstruction).
The consequence of either form of angle closure leads reduced aqueous outflow through the trabecular meshwork. The mechanisms of angle closure can be categorized into:
- mechanisms that push the iris forward from behind.
- mechanisms that pull the iris forward into contact with the trabecular meshwork.
References
- ↑ Weinreb RN, Aung T, Medeiros FA (2014). "The pathophysiology and treatment of glaucoma: a review". JAMA. 311 (18): 1901–11. doi:10.1001/jama.2014.3192. PMC 4523637. PMID 24825645.
- ↑ Dudziak R (1978). "[Response to the comment on R. Dudziak and M. Uihlein: "Solubility of local anesthetics in cerebrospinal fluid and its dependence from hydrogen-ion concentration"]". Anaesthesist. 27 (5): suppl 45-6. PMID https://www.ncbi.nlm.nih.gov/pmc/articles/PMC27126 Check
|pmid=value (help).