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Sclera
From Wikipedia, the free encyclopedia
| Sclera | |
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| Schematic diagram of the human eye. | |
| Gray's | subject #225 1006 |
| Artery | anterior ciliary arteries, long posterior ciliary arteries, short posterior ciliary arteries |
| MeSH | Sclera |
The sclera is the opaque (usually white- certain animals, such as horses, lizards, etc. - can have black sclera ), fibrous, protective, outer layer of the eye containing collagen and elastic fibers.[1] In children, it is thinner and shows some of the underlying pigment, appearing slightly blue. In the elderly, however, fatty deposits on the sclera can make it appear slightly yellow.
The sclera forms the posterior five sixths of the connective tissue coat of the globe. It is continuous with the dura mater, and maintains the shape of the globe, offering resistance to internal and external forces, and provides an attachment for the extraocular muscle insertions. The thickness of the sclera varies from 1mm at the posterior pole to 0.3 mm just behind the rectus muscle insertions.
It borders with the cornea by the corneal limbus.
Contents |
From outer to innermost, the three layers of the sclera are:
- Episclera
- Stroma
- Lamina fusca
To avoid confusion, the cornea, which is an outer continuation from the sclera, has 5 layers. The middle, thickest layer is also called the stroma. Lazic surgery to correct vision is usually done in this region of the cornea.
 Interior of anterior half of bulb of eye. |
 The terminal portion of the optic nerve and its entrance into the eyeball, in horizontal section. |
 The interior of the posterior half of the left eyeball. |
- ^ Cassin, B. and Solomon, S. Dictionary of Eye Terminology. Gainesville, Florida: Triad Publishing Company, 1990.
- Histology at BU 08008loa
- Atlas of anatomy at UMich eye_1 - "Sagittal Section Through the Eyeball"
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This eye article is a stub. You can help Wikipedia by expanding it. |
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| Fibrous tunic (outer) | Conjunctiva • Sclera • Schlemm's canal • Trabecular meshwork • Limbus Cornea (Epithelium, Bowman's, Stroma, Descemet's, Endothelium) |
| Uvea (middle) | Choroid (Ciliary processes, Choriocapillaris, Bruch's membrane) • Iris (Stroma) • Pupil • Ciliary body |
| Retina (inner) | Macula • Fovea • Optic disc |
| Anterior segment | Anterior chamber • Aqueous humour • Posterior chamber • Lens |
| Posterior segment | Vitreous humour • Zonular fibers • Zonule of Zinn |
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| Eye • Optic nerve • Optic chiasm • Optic tract • Lateral geniculate nucleus • Optic radiation • Visual cortex • Blobs |