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45 terms

Eye Lab 10

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Fibrous tunic
Protective layer composed of dense avascular connective tissue, Outermost layer, Sclera & Cornea
Sclera
inside of the fibrous tunic, opaque white region that composes bulk of the fibrous tunic. Observed anteriorly as the "white of the eye"
Cornea
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
Choroid
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
Iris
anterior most portion of the vascular tunic/uvea. This is the portion where you get the color in your eyes
Pupil
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
Retina
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
Lens
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)
Rods
Specialized receptors for dim light, Visual interpretation is in gray tones
Cones
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
Astigmatism
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
Protanopia
Red Color Blindness
Deuteranopia
Green Color Blindness
Tritanopia
Blue Color Blindness