The trabecular meshwork is an area of tissue in the eye located around the base of the

cornea The cornea is the transparency (optics), transparent front part of the eyeball which covers the Iris (anatomy), iris, pupil, and Anterior chamber of eyeball, anterior chamber. Along with the anterior chamber and Lens (anatomy), lens, the cornea ...

, near the

ciliary body The ciliary body is a part of the eye that includes the ciliary muscle, which controls the shape of the lens, and the ciliary epithelium, which produces the aqueous humor. The aqueous humor is produced in the non-pigmented portion of the ciliary ...

, and is responsible for draining the aqueous humor from the eye via the

anterior chamber The anterior chamber ( AC) is the aqueous humor-filled space inside the eye between the iris and the cornea's innermost surface, the endothelium. Hyphema, anterior uveitis and glaucoma are three main pathologies in this area. In hyphema, ...

(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 which is lined by endothelium with blood and lymphatic properties that allow aqueous humor to flow into the blood system.

Structure

The meshwork is divided up into three parts, with characteristically different ultrastructures: #''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. #''Corneoscleral meshwork'' - Contains a large amount of

elastin Elastin is a protein encoded by the ''ELN'' gene in humans and several other animals. Elastin is a key component in the extracellular matrix of gnathostomes (jawed vertebrates). It is highly Elasticity (physics), elastic and present in connective ...

, arranged as a series of thin, flat, perforated sheets arranged in a laminar pattern; considered the

ciliary muscle The ciliary muscle is an intrinsic muscle of the eye formed as a ring of smooth muscleSchachar, Ronald A. (2012). "Anatomy and Physiology." (Chapter 4) . in the eye's middle layer, the uvea ( vascular layer). It controls accommodation for vie ...

tendon A tendon or sinew is a tough band of fibrous connective tissue, dense fibrous connective tissue that connects skeletal muscle, muscle to bone. It sends the mechanical forces of muscle contraction to the skeletal system, while withstanding tensi ...

. #''Juxtacanalicular tissue'' (also known as the ''cribriform meshwork'') - Lies immediately adjacent to Schlemm's canal, composed of connective tissue

ground substance Ground substance is an amorphous gel-like substance in the extracellular space of animals that contains all components of the extracellular matrix (ECM) except for fibrous materials such as collagen and elastin. Ground substance is active in the d ...

full of glycoaminoglycans and

glycoproteins Glycoproteins are proteins which contain oligosaccharide (sugar) chains covalently attached to amino acid side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known a ...

. 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 Glaucoma is a group of eye diseases that can lead to damage of the optic nerve. The optic nerve transmits visual information from the eye to the brain. Glaucoma may cause vision loss if left untreated. It has been called the "silent thief of ...

drugs such as prostaglandins (e.g., Xalatan, Travatan). The trabecular meshwork had previously been thought to arise from a point (apex) corresponding to the termination of the DM ( Schwalbe's line) however it is now considered to extend into the cornea, forming the Dua's layer.

Clinical significance

Glaucoma

It is thought that most cases of glaucoma (although not all) are caused or enabled 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. When outflow is blocked, interventions such as trabeculectomy, trabeculoplasty, or aqueous shunt may be required to restore it.

References

External links

*
Diagram at glaucoma-association.com
{{Eye Human eye anatomy

Structure

Clinical significance

Glaucoma

See also

References

External links