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10 Cards in this Set
- Front
- Back
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Diopter
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maybe the most archaic term we have learned yet
diopter = 1/focal length of lens the more diopters you have the better your eyes can accomodate to see things close up |
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myopia
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near sited
can see near objects, squints to see far away objects excessive refractive power or eye and/or eyeball is too big fix w/ concave lens |
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hyperopia
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far sited
can see far away objects, holds objects at a distance to read inadequate refractive power and/or eye is too small fix w/ convex lens |
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astigmatism
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egg shaped eye
variable curvatures and variable focal points fix w/ cylindrical lens to induce single focal point that can then be fixed w/ concave or convex lenses |
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Presbyopia
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accommodation of eye wears out (42-45 y/o)
reading glasses or bifocals |
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Aphakia
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lens is removed (loss of 20 diopters)
tx: coke bottle glasses, confact lens, cataract surgery (implant new lens) |
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Refractive surgeries
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Radial Keratotomy
Photorefractive Keratotomy Lasix (not the diuretic) Intracorneal rings |
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Radial Keratotomy
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4-8 incisions made and allowed to heal
85% --> 20/40 best in 3.00-6.00 diopter range complications involved problems w/ healing incorrectly newer surgeries have replaced it |
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Photorefractive Keratotomy
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Excimer laser vaporizes corneal tissue
can flatter or steepen corneal apex complications - post op pain and longer recovery than lasix easier and cheaper than lasix |
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Lasix
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procedure of choice for -12.00 to +6.00 diopter
fold back cornea, laser like PRK, put back cornea |
