Stroma of cornea

Stroma of cornea
Vertical section of human cornea from near the margin. (Waldeyer.) Magnified. 1. Epithelium. 2. Anterior elastic lamina. 3. substantia propria. 4. Posterior elastic lamina. 5. Endothelium of the anterior chamber. a. Oblique fibers in the anterior layer of the substantia propria. b. Lamellæ the fibers of which are cut across, producing a dotted appearance. c. Corneal corpuscles appearing fusiform in section. d. Lamellæ the fibers of which are cut longitudinally. e. Transition to the sclera, with more distinct fibrillation, and surmounted by a thicker epithelium. f. Small blood vessels cut across near the margin of the cornea.
Latin	s. propria corneae
Gray's	subject #225 1007

The substantia propria (or stroma of cornea) is fibrous, tough, unyielding, and perfectly transparent.

It is composed of about 200 flattened lamellæ (plates of collagen fibrils), superimposed one on another.^[1] They are each about 1.5-2.5 micrometres in thickness. These fibrils run at different angles between the limbi. Fibres of the layers frequently interweave, the anterior lamellæ interweaving more than posterior lamellæ. The fibres of each lamella are parallel with one another, but at right angles to those of adjacent lamellæ. The lamellæ are produced by keratocytes (corneal corpuscles), which occupy about 10% of the substantia propria.

These lamellæ are made up of bundles of modified connective tissue, the fibres of which are directly continuous with those of the sclera. More collagen fibres run in a temporal-nasal direction than run in the superior-inferior direction. This is often ignored by corneal transplant surgeons, leading to poor corneal mechanical strength in corneal transplant patients.^{[citation needed]}

[edit] Disorders of stroma

• Keratoconus is a condition caused by disorganised lamellæ, leading to thinned and conical-shaped cornea.
• Macular corneal dystrophy, associated with the loss of keratan sulfate

[edit] References

1. ^ Oyster, C. (1999) The Human Eye Structure and Function, Sinauer, §8

[edit] External links

• Diagram at pacificu.edu

v • d • e Sensory system – visual system – globe of eye (TA A15.2.1-6, GA 10.1005) Fibrous tunic (outer) Sclera Episcleral layer • Schlemm's canal • Trabecular meshwork Cornea Limbus • layers (Epithelium, Bowman's, Stroma, Descemet's, Endothelium) Uvea/vascular tunic (middle) Choroid Capillary lamina of choroid • Bruch's membrane • Sattler's layer Ciliary body Ciliary processes • Ciliary muscle Iris Stroma • Pupil • Iris dilator muscle • Iris sphincter muscle Retina (inner) Layers Inner limiting membrane • Nerve fiber layer • Ganglion cell layer • Inner plexiform layer • Inner nuclear layer Outer plexiform layer • Outer nuclear layer External limiting membrane • Layer of rods and cones • Retinal pigment epithelium Other Macula • Foveola • Fovea • Optic disc (Cup) Anterior segment Anterior chamber • Aqueous humour • Posterior chamber • Lens (Capsule of lens, Zonule of Zinn) Posterior segment Vitreous humour Other Ocular immune system • Tapetum lucidum • Keratocytes M: EYE anat(g, a, p)/phys/devp/cell noco/cong/tumr, epon proc, drug(S1A/1E/1F/1L)