{{short description|Annular structure composed of collagen in the human eye}} {{More citations needed|date=June 2009}}{{Infobox brain|Name=Scleral spur|Image=Gray870 rotated.jpg|Caption=Enlarged general view of the iridial angle (Scleral spur appear at upper right)|Latin=Calcar sclerae|System=Visual system|Function=|Location=}}
The '''scleral spur''' in the visual system is a protrusion of the sclera (the white of the eye) into the anterior chamber. The spur is an annular structure composed of collagen in the human eye.
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)<ref>{{Cite book|title=Gray's Anatomy: The Anatomical Basis of Clinical Practice|publisher=Elsevier|year=2015|isbn=978-0-7020-5230-9|edition=41st|pages=693}}</ref> of the ciliary muscle, and is attached posteriorly 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, ultimately resulting in decreasing of the intraocular pressure.<ref>Neal, M. J. (2004). "Medical Pharmacology at a Glance" (6th edition). Wiley-Blackwell. p. 27. {{ISBN|978-1-4051-5044-6}}</ref>
==Additional images== <gallery> File:Anterior chamber angle - 3D motion parallax.gif|Gonioscopy of the anterior chamber angle File:Kammerwinkel.jpg|Gonioscopy of the anterior chamber angle. Labeled structures: 1. Schwalbe's line, 2. Trabecular meshwork (TM), 3. Scleral spur, 4. Ciliary body, 5. Iris File:SD OCT - Anterior Chamber Angle Cross-Section (with viewfinder).png|Anterior chamber angle cross-section imaged by an SD-OCT. </gallery>
==See also== *Eye care professional *Ophthalmology *Orthoptics *Vision rehabilitation
==References== {{Reflist}}
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{{DEFAULTSORT:Scleral Spur}} Category:Human eye anatomy