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Related Flashcards
Cards In This Set
| Front | Back |
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Eye is protected by what?
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Bony orbital cavity, which is surrounded by a cushion of fat
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Palpebral fissure
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Elliptical open space between upper and lower lid
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What provides eye irrigation through tears?
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Lacrimal apparatus
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Where do tears drain?
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Puncta
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Extraocular muscles
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6 muscles attach eyeball to orbit and serve to direct the eye to points of gaze
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Extraocular muscles are stimulated by which cranial nerves?
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CN III (oculomotor)
CN IV (trochlear)
CN VI (abducens)
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When looking at an object, how are light rays reflected?
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From object to cornea, light rays are bent (refracted) an focused by cornea, lens, vitreous.
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What is the lens' job?
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Make sure the rays come to a sharp focus on the retina
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The image on the retina is in what direction?
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Upside down!
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At the retina, light rays are converted to what?
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Electrical impulses, then transmitted through ptic nerve to brain, where image is translated and perceived in an upright position.
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Definition of myopia
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Nearsightedness, caused by light rays focusing in front of the retina
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Causes of myopia
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Excessive light refraction by cornea/lens, LONG eye, lens swelling w/ hyperglycemia, developmental growth spurts.
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What type of lens does a person with myopia need?
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Minus prescription, concave lenses.
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Definition of hyperopia
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Light focuses behind the retina (farsighted), must have accommodation to focus the light rays on the retina
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Causes of hyperopia?
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Inadequate focusing power, eyeball too short
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