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Fibrous tunic

Protective layer composed of dense avascular connective tissue, Outermost layer, Sclera & Cornea


inside of the fibrous tunic, opaque white region that composes bulk of the fibrous tunic. Observed anteriorly as the "white of the eye"


inside of the fibrous tunic, anterior most portion of fibrous tunic. Modified structurally to form a transparent layer. This is where light enters the eye

Vascular tunic (Uvea)

consits of the choroid, ciliary body, iris, pupil


inside the vascular tunic, rich vascular nutritive layer containing a dark pigment that prevents light scattering within the eye. Posterior most portion of uvea

Ciliary body

inside the vascular tunic, modified anterior structure of the choroid. Consists of the following 2 structures: ciliary muscles & ciliary processes

Ciliary muscles

important in controlling lens shape

Ciliary processes

produce aqueous humor


anterior most portion of the vascular tunic/uvea. This is the portion where you get the color in your eyes


part of the vascular tunic/uvea. the opening in the iris which allows light to pass into the eye

Sensory tunic

innermost tunic of the eye, consists of the retina, optic disc, macula lutea, & fovea centrallis


delicate two layered (pigmented epithelial layer & neural layer) structure, is part of the sensory tunic

Pigmented epithelial layer

outer pigmented layer of retina that abuts the choroid and extends anteriorly to cover the ciliary body and posterior sides of the iris

Neural layer (nervous layer)

inner transparent layer of retina that extends anteriorly only to the ciliary body. Contains the photoreceptors rods and cones

Optic disc (blind spot)

part ot the sensory tunic, site where the optic nerve leaves the eyeball (contains no photoreceptors)

Macula Lutea (yellow spot)

part of the sensory tunic, lateral to the optic disc and directly posterior to the lens. An area of high cone density

Fovea Centralis

part of the sensory tunic. center of the macula Lutea. Small pit that contains mostly cones and is the area of greatest visual acuity

lateral rectus

moves eye laterally

VI abducens

what is the controlling cranial nerve of the lateral rectus?

medial rectus

moves eyes medially, oculomotor III is the controlling cranial nerve

superior rectus

elevates eye, oculomotor III is the controlling cranial nerve

inferior rectus

depresses eye, oculomotor III is the controlling cranial nerve

inferior oblique

elevates eye and turns it laterally, oculomotor III is the controlling cranial nerve

superior oblique

depresses eye and turns it laterally, trochlear IV


focuses the light entering the eye onto the retina. A flexible crystalline structure held vertically in the eye's interior by suspensory ligaments attached to the ciliary body

Anterior segment

those portions of the eye anterior to the lens. Contains the clear watery fluid called aqueous humor. Divided into two parts: Anterior & posterior chamber

Anterior chamber

anterior to the iris

Posterior chamber

posterior to the iris

Posterior segment

those portions of the eye posterior to the lens. Contains the gel-like substance called vitreous humor (vitreous body)


Specialized receptors for dim light, Visual interpretation is in gray tones


Color receptors that permit high levels of visual acuity, Only function under high light intensity

Optic nerve

Formed from the axons of the ganglion cells leaving the retina. Attaches to the retina at the optic disc

Optic nerve

where ganglion cells of the retina converge at posterior aspect of eyeball and exit from the eye

Optic Chiasma

where fibers from medial side of each eye cross over to the opposite side

Optic tracts

contain fibers from lateral side of eye on the same side and medial side of eye from opposite side

Lateral Geniculate nucleus

optic tract fibers synapse with neurons. Located in thalamus

Optic radiations

the axons of the optic tracts that terminate in the visual (optic) cortex

visual acuity

Sharpness of vision. Typically tested using a Snellen Eye Chart. Results given as a ratio of distances from what you see over what a normal eye sees (i.e. 20/20 vision)

Myopia (Nearsightedness)

Image is focused in front of the retina. No problem with close vision, but far objects are blurred or seen indistinctly. Correction requires a concave lens

Hyperopia (Farsightedness)

Image is focused behind the retina. No problem with distant vision, but close objects are blurred or seen indistinctly. Correction requires a convex lens


Defect in curvature of the lens and/or cornea. Tested with an A Chart. and spacing. Correct with a cylindrical lens

Presbyopia (Old Vision)

difficulty in focusing for near or far vision, due to elasticity of lens decreasing


Red Color Blindness


Green Color Blindness


Blue Color Blindness

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