Scleral spur

Scleral spur
	Enlarged general view of the iridial angle (Scleral spur appear at upper right)
Details
System	Visual system
Identifiers
Latin	Calcar sclerae
	Anatomical terms of neuroanatomy

The scleral spur is an annular structure composed of collagen in the human eye, a protrusion of the sclera into the anterior chamber.

It is the origin of the longitudinal and circular fibres (which swerve acutely from the spur to run circumferentially, as a sphincter near the periphery of the lens)[1] of the ciliary muscle, and is attached anteriorly to the trabecular meshwork.

Role in treatment of Glaucoma

Open-angle glaucoma (OAG) and closed-angle glaucoma (CAG) may be treated by muscarinic receptor agonists (e.g., pilocarpine), which cause rapid miosis and contraction of the ciliary muscles, this pulls the scleral spur and results in the trabecular meshwork being stretched and separated.

This opens the fluid pathways, and facilitates drainage of the aqueous humour, into the canal of Schlemm and ultimately results in decreasing of the intraocular pressure.[2]

References

Gray's Anatomy: The Anatomical Basis of Clinical Practice (41st ed.). Elsevier. 2015. p. 693. ISBN 978-0-7020-5230-9.
Neal, M. J. (2004). "Medical Pharmacology at a Glance" (6th edition). Wiley-Blackwell. p. 27. ISBN 978-1-4051-5044-6

Additional images

Gonioscopy of the anterior chamber angle
Gonioscopy of the anterior chamber angle. Labeled structures: 1. Schwalbe's line, 2. Trabecular meshwork (TM), 3. Scleral spur, 4. Ciliary body, 5. Iris
Anterior chamber angle cross-section imaged by an SD-OCT.

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[1] Gray's Anatomy: The Anatomical Basis of Clinical Practice (41st ed.). Elsevier. 2015. p. 693. ISBN 978-0-7020-5230-9.

[2] Neal, M. J. (2004). "Medical Pharmacology at a Glance" (6th edition). Wiley-Blackwell. p. 27. ISBN 978-1-4051-5044-6