[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Head and neck](https://durgical.com/en/anatomy/region/head-and-neck/) › Sclera [Sense organs](https://durgical.com/en/anatomy/system/sense-organs/) · [Head and neck](https://durgical.com/en/anatomy/region/head-and-neck/) # Sclera The sclera is the tough white outer coat of the eye; it protects the eyeball and anchors the muscles that move it. [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=head_neck&select=sclera&side=r) Opens in the Durgical app, no sign-up needed. ## What it is The tough white outer coat of the eye. ## What it does Protects the eye and anchors the eye muscles. ## Key points - Thinnest just behind the insertions of the rectus muscles: with the limbus, the usual rupture site after blunt trauma - Scleritis: deep, boring pain that can wake the patient, a violet-red tender eye, often with systemic disease (rheumatoid arthritis, granulomatosis with polyangiitis); episcleritis is milder and usually self-limiting - Blue sclera, where the dark choroid shows through a thin coat, is a sign of osteogenesis imperfecta - At the back its fibres form the lamina cribrosa, the sieve the optic nerve axons pass through, and its outer layers continue as the dural sheath of the optic nerve ## Key facts **Where** Posterior five sixths of the outer coat **Blood supply** Episcleral and anterior ciliary vessels **Nerve** Ciliary nerves **Function** Protects the eye, anchors the eye muscles ## Relations **In front** [Cornea](https://durgical.com/en/anatomy/cornea/) at the limbus, where Schlemm canal runs within it **Behind** [Optic nerve](https://durgical.com/en/anatomy/optic-nerve/), whose dural sheath blends with it **Superficial** Episclera and Tenon capsule (fascia bulbi), and at the front the conjunctiva **Deep** [Choroid](https://durgical.com/en/anatomy/choroid/) and [ciliary body](https://durgical.com/en/anatomy/ciliary-body/), across the suprachoroidal space **Contents** Canals for the posterior ciliary arteries and nerves around the optic nerve, the vortex veins behind the equator and the anterior ciliary vessels near the limbus ## How to find it The white of the eye, seen through the clear conjunctiva; the tendons of the extraocular muscles such as the [superior rectus](https://durgical.com/en/anatomy/superior-rectus-muscle/) and [lateral rectus](https://durgical.com/en/anatomy/lateral-rectus-muscle/) insert on it in front of the equator. Its back part is seen only on imaging or at surgery. ## Examination - Phenylephrine drop test: superficial episcleral vessels blanch (episcleritis), deep scleral vessels do not (scleritis) - Inspection in daylight: a bluish-violet hue suggests scleritis; tenderness to gentle pressure through the lid supports it - Exophthalmometry measures how far the globe sits forward: high in thyroid eye disease or an orbital mass, low (enophthalmos) after a blow-out fracture of the orbital floor ## On imaging B-scan ultrasound shows posterior scleritis as a thickened coat with fluid in Tenon space around the optic nerve (T sign); CT helps when a hidden rupture is suspected. B-scan also looks inside the eye when a dense cataract or [vitreous](https://durgical.com/en/anatomy/vitreous-body/) blood hides it. After trauma CT comes first; MRI waits until a metal foreign body is excluded. ## Clinical notes - Necrotizing scleritis can thin the sclera until the choroid shows; painless thinning in long-standing rheumatoid arthritis is scleromalacia perforans - A scleral buckle sewn onto it indents the wall to close a retinal tear - In high myopia the globe is too long for its optics (normal adult axial length is about 23–24 mm) and can bulge backward (posterior staphyloma); such eyes are also prone to retinal tears - Open globe: a full-thickness wound of sclera or cornea is suggested by a peaked pupil, a shallow [anterior chamber](https://durgical.com/en/anatomy/anterior-chamber-of-eyeball/) or dark uveal tissue at the wound - Sympathetic ophthalmia: a rare inflammation of the uninjured eye weeks to months after a penetrating injury to the other ## Development Forms from neural crest mesenchyme that condenses around the optic cup. ## Related conditions - [Ocular trauma: hyphema and open globe injury](https://durgical.com/en/conditions/ocular-trauma-hyphema-and-open-globe-injury/) - [Scleritis and episcleritis](https://durgical.com/en/conditions/scleritis-and-episcleritis/) - [Retinal detachment](https://durgical.com/en/conditions/retinal-detachment/) - [Conjunctivitis](https://durgical.com/en/conditions/conjunctivitis/) ## Test yourself Think of the answer, then tap the question to see it. ## Where is the sclera thinnest, and where does it usually rupture after blunt trauma? Just behind the insertions of the rectus muscles; this zone and the limbus are the usual rupture sites. ## How does scleritis differ from episcleritis? Scleritis gives deep, boring pain that can wake the patient and a violet-red tender eye, often with systemic disease; episcleritis is milder and usually self-limiting. ## What does the phenylephrine drop test show in a red eye with suspected scleral inflammation? Superficial episcleral vessels blanch (episcleritis); deep scleral vessels do not (scleritis). ## What does a blue sclera indicate? Osteogenesis imperfecta: the dark choroid shows through a thin scleral coat. ## Which scan comes first when a metal foreign body may have entered the eye through the sclera? CT; MRI is avoided until metal has been excluded. [Add to my cards (5)](https://durgical.app/estudiar/?add=/en/anatomy/sclera/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** sclera TA2 6750 **Official Spanish (DeCS)** Esclerótica DeCS D012590 **English (TA2)** Sclera **Also called** white of the eye ## Related - [Choroid](https://durgical.com/en/anatomy/choroid/) Sources: Terminologia Anatomica (TA2); [DeCS](https://decs.bvsalud.org/es/ths/resource/?id=12971); [Scleritis](https://www.ncbi.nlm.nih.gov/books/NBK499944/); [Anatomy, Head and Neck, Eye](https://www.ncbi.nlm.nih.gov/books/NBK482428/); [14.1 Sensory Perception](https://openstax.org/books/anatomy-and-physiology-2e/pages/14-1-sensory-perception) (OpenStax (Rice University), 2022) · adapted, [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/sclera/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/sclera/