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16 Cards in this Set
- Front
- Back
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layers of the eye
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outer sclera; cornea as anterior 1/6
middle choroid/uvea- vascular and pigmented; forms ciliary body and iris stroma anteriorly inner retina |
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vitreous vs aquaeous humor
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vitreous- gelatinous with phagocytes; behind lens
aqueous humor- prod in posterior chamber( b/w iris and lens) by ciliary body; imp for intraocular pressure (glaucoma); drains through canal of schlem |
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what is the first layer of the eye to focus light?
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cornea
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what is the output of the retina?
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retinal ganglion cells; their axons form CN II
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what wraps around CN II?
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meningeal layer with CSF
build up of CSF-> compression of CNII -> damage/elevation of optic disc and retinal hemorrhage (papilledema) |
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what happens to light as it passes through the lens?
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it forms an inverted, reversed image on the retina
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what are the 2 focusing elements of the eye? which is the most powerful?
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cornea (2X as powerful) and lens
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what shape is the lens? what does this do?
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convex; focuses light on the focal pt
(distance from lens to focal pt = focal length) |
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how does focal length change with the shape of the lens?
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flatter lens-> longer focal length
more convex-> decr FL |
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what is a diopter?
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describes power of the lens
D= 1/FL |
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what is myopia?
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nearsighted-light focuses too close (thick cornea or long eyeball)
use concave lens to adjust (incr FL) |
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what is hyperopia?
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farsighted -light focuses too far away
(thin cornea or short eyeball) use convex lens to shorten FL |
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accomodation
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lens bulges with close vision in order to have enough refractive power to focus the image
distance vision- flat lens; taught zonule fibers and relxed ciliary mm. close vision- fat lens; loose zonule fibers, contracted ciliary m. |
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what is presbyopia?
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loss of ability of lens to accomodate with age
due to loss of elasticity of lens |
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what is a method by which we incr resolution of an image?
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reduce size of pupil
(PSNS innervates sphincter of iris) (side note: SNS innervates dilator m. of iris) |
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what 3 things happen when we accomodate?
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"near relfex"
pupil constricts eyes converge eyes accomodate all via CN III and Edinger Westphal nucleus |
