Trabecular meshwork

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Trabecular meshwork
Enlarged general view of the iridial angle. (When enlarged, visible with older label of 'trabecular tissue')
Latin	reticulum trabeculare sclerae
Gray's	subject #225 1006
MeSH	Trabecular+Meshwork

The trabecular meshwork is an area of tissue in the eye located around the base of the cornea, near the ciliary body, and is responsible for draining the aqueous humor from the eye via the anterior chamber (the chamber on the front of the eye covered by the cornea).

The tissue is spongy and lined by trabeculocytes; it allows fluid to drain into a set of tubes called Schlemm's canal flowing into the blood system.

Parts

The meshwork is divided up into three parts, with characteristically different ultrastructures:

1. Inner uveal meshwork - Closest to the anterior chamber angle, contains thin cord-like trabeculae, orientated predominantly in a radial fashion, enclosing trabeculae spaces larger than the corneoscleral meshwork.
2. Corneoscleral meshwork - Contains a large amount of elastin, arranged as a series of thin, flat, perforated sheets arranged in a laminar pattern.
3. Juxtacanalicular tissue (also known as the cribriform meshwork) - Lies immediately adjacent to Schlemm's canal, composed of connective tissue ground substance full of glycoaminoglycans and glycoproteins. This thin strip of tissue is covered by a monolayer of endothelial cells.

The trabecular meshwork is assisted to a small degree in the drainage of aqueous humour by a second outflow pathway, the uveo-scleral pathway (5-10% of outflow occurs this way). The uveo-scleral pathway is increased with the use of glaucoma drugs such as prostaglandins (e.g., Xalatan, Travatan).

Role in Glaucoma

Glaucoma is thought to be caused by an increase in intraocular pressure. Pressure increases either when too much aqueous humor fluid is produced or by decreased aqueous humor outflow. The Trabecular meshwork is responsible for most of the outflow of aqueous humor.

See also

• Argon laser trabeculoplasty
• Glaucoma
• Intraocular pressure
• Ocular hypertension
• Trabeculectomy

External links

• Histology at BU 08005loa
• trabecular+reticulum at eMedicine Dictionary
• Diagram at glaucoma-association.com

v • d • e Sensory system – visual system – globe of eye (TA A15.2.1-6, GA 10.1005) Fibrous tunic (outer) Conjunctiva Plica semilunaris Sclera Episcleral layer • Schlemm's canal • Trabecular meshwork Cornea Limbus • layers (Epithelium, Bowman's, Stroma, Descemet's, Endothelium) Uvea/vascular tunic (middle) Choroid Capillary lamina of choroid • Bruch's membrane • Sattler's layer Ciliary body Ciliary processes • Ciliary muscle Iris Stroma • Pupil • Iris dilator muscle • Iris sphincter muscle Retina (inner) Cells Photoreceptor cells (Cone cell, Rod cell) → (Horizontal cell) → Bipolar cell → (Amacrine cell) → Retinal ganglion cell (Giant retinal ganglion cells, Photosensitive ganglion cell) Muller glia Layers Inner limiting membrane • Nerve fiber layer • Ganglion cell layer • Inner plexiform layer • Inner nuclear layer Outer plexiform layer • Outer nuclear layer External limiting membrane • Layer of rods and cones • Retinal pigment epithelium Other Macula • Foveola • Fovea • Optic disc (Cup) Anterior segment Anterior chamber • Aqueous humour • Posterior chamber • Lens (Capsule of lens, Zonule of Zinn) Posterior segment Vitreous humour Other Ocular immune system • Tapetum lucidum eye navs: anat/adnexa anat/pathways/physio/dev, noncongen/congen/neoplasia, eponymous signs, proc