The eye

一. Layers of the eye  corneoscleral coat : fibrous layer, include the sclera, the white portion,and the cornea, the transparent portion.  vascular coat : include the choroid, the stroma of the ciliary body and iris.  retina : the inner layer, include an outer pigment epi. The inner neural retina, and the epi. Of the ciliary body and iris.

eyeball pupil lens iris Ciliary body Optic nerve macula cornea sclera retina choroid

cornea  Corneal epi.: nonkeratinized stratified squamous epi.,5-6 layers of cells.  Bowman’s membrane ： anterior basement membrane,a homogeneous-appearing layer on which the corneal epi.rests.  Corneal stroma: composed of thin lamellae each lamella consists of parallel bundles of collagen fibrils. No blood or lymphatic vessels.  descemet’s membrane ： posterior basement membrane,is the basal lamina of corneal endothelial cells. Separates the corneal endothelium from the adjacent corneal stroma.  Corneal endothelium ： a single layer of squamous cells covering the surface of the cornea that faces the anterior chamber. Provides for metabolic exchange between the cornea and aqueous humor.

Cormeal epithelium Anterior basement membrane Corneal stroma Posterior basement membrane Corneal endothelium

sclera  Is an opaque layer that consists predominantly of dense CT.  The corneoscleral limbus : is the transitional zone between the cornea and sclera. An abrupt transition from the avascular cornea to the well-vascularized sclera occurs here.  Sclera venous sinus: in the irisocorneal angle contains the apparatus for the outflow of aqueous humor which is produced by the ciliary processes.

sclera

Anterior chamber Scleral venous sinus Trabecular meshwork

iris 1.anterior layer ： a discontinuous layer of fibroblasts and melanocyte. 2.stroma ： LCT, highly vascularized and with abundant pigmented cells. constrictor pupillae muscle. 3.epi. : anterior-myoepithelium, dilator pupillae muscle. posterior-pigment epithelial cells. Pupil locate in the center. Anterior chamber ： between the iris and the cornea. Posterior chamber ： between the iris and vitreous body.

iris 前房 Posterior chamber Constrictor Pupillae M Anterior chamber

Ciliary body  Is the thickened anterior portion of the vascular coat and is located between the iris and choroid. Ciliary muscle The stroma Epithelial layer

Ciliary processlens

retina Represent the innermost layer of the eye Neural retina: inner layer that contains photoreceptors. RPE, the outer layer that rests on and attached to the choroid.

Neural retina  Nonvisual part,  Optic part.  Optic papilla: where the optic nerve joins the retina. Is devoid of photoreceptors. A blind spot in the visual field.  Fovea centralis : a shallow depression located lateral to the optic papilla. Is the area of greatest visual acuity.  Macula lutea: a yellow-pigmented zone surrounds the fovea.

pigment epi. Ganglion C Bipolar C Cone C Rod C

sclera choroid Pigmented Epi. Ganglion C retina retina

Nuclei of visusl C External processes Pigmented epi. Visual cell （ HE ）

Macula lutea & fovea centralis

Optic papilla

Lens capsule Epi. Lens fiber Crystalline lens

 Is a transparent, avascular, biconvex structure.  The components of the lens: ① lens capsule, a thick basal lamina ② subcapsular epi., a cuboidal layer of cells. on the anterior face of the lens cells. on the anterior face of the lens ① lens fibers, derived from subcapsular epi.

Vitreous body

 Is the transparent jelly-like substance that fill the vitreous chamber in the posterior segment of the eye.