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The sclera (plural: scleras or sclerae) is the fibrous, opaque white, coat of the eye. It functions to protect the intraocular contents.
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location: posterior fifth-sixths of the eyeball
blood supply: ciliary arteries
innervation: ciliary nerves
relations: anteriorly continuous with the cornea
Outermost coat of the trilaminar globe. Anteriorly continuous with the cornea. Posteriorly perforated by the optic nerve at the lamina cribrosa.
Sclera is continuous with dura, pia, and arachnoid sheaths of the optic nerve 2.
anteriorly, the anterior ciliary arteries form a dense episcleral plexus
posteriorly, supplied by branches of the short and long posterior ciliary arteries
The sclera is an alymphatic organ.
Anteriorly supplied by the long ciliary nerves. Posteriorly supplied by the short ciliary nerves.
The sclera may be divided into three histological layers:
outermost, loose connective tissue layer, connected to the Tenon capsule
rich vascular supply from anterior ciliary arteries
dense fibrous tissue intermingled with fine elastic fibers
irregular arrangement of type I and III collagen responsible for its opacity
innermost layer with melanocytes
weakly related to the choroid
Ultrasound and CT are not useful modalities.
Anterior segment ocular coherence tomography (AS-OCT)
readily used in clinical practice to measure scleral thickness, monitor therapeutic response in scleritis treatment
quantitative measurements obtained
useful in the diagnosis of posterior scleritis and episcleritis
T1-weighted sequences, sclera appears as the hypointense rim of the globe
History and etymology
The word derives from medical Latin, itself from the Greek sklera "the hard (membrane)," feminine form of skleros "hard".
episcleritis/scleritis: inflammation of the sclera
staphyloma: full or partial thickness scleral defect lined by the uvea
- 1. Richard S. Snell, Michael A. Lemp. Clinical Anatomy of the Eye. (2013) ISBN: 9781118691007
- 2. Barral J & Croibier A. Optic Nerve. Manual Therapy for the Cranial Nerves. 2009;:73-89. doi:10.1016/b978-0-7020-3100-7.50014-8