WWK- Structure of the human eye

sclera

the white outer layer of the eyeball. At the front of the eye it is continuous with the cornea.

cornea

the transparent layer forming the front of the eye.

lacrimal glands

Lacrimal gland definition, either of two tear-secreting glands situated in the upper outer angle of the orbit.

iris

a flat, coloured, ring-shaped membrane behind the cornea of the eye, with an adjustable circular opening (pupil) in the centre.

pupil

the dark circular opening in the centre of the iris of the eye, which varies in size to regulate the amount of light reaching the retina.

cilairy muscles

the part of the eye that connects the iris to the choroid

aqueous humor

the clear fluid filling the space in the front of the eyeball between the lens and the cornea.

lens

a piece of glass or other transparent material with curved sides for concentrating or dispersing light rays

vitreous humor

the transparent jelly-like tissue filling the eyeball behind the lens.

retina

a layer at the back of the eyeball that contains cells sensitive to light, which trigger nerve impulses that pass via the optic nerve to the brain, where a visual image is formed.

chorioid

the pigmented vascular layer of the eyeball between the retina and the sclera.

macula

an oval yellowish area surrounding the fovea near the centre of the retina in the eye, which is the region of keenest vision.

fovea

a small depression in the retina of the eye where visual acuity is highest. The centre of the field of vision is focused in this region, where retinal cones are particularly concentrated.

optic disk

the raised disc on the retina at the point of entry of the optic nerve, lacking visual receptors and so creating a blind spot.

blind spot

an area where a person's view is obstructed.

optic nerve

each of the second pair of cranial nerves, transmitting impulses to the brain from the retina at the back of the eye.