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59 Cards in this Set
- Front
- Back
Refrative power of a lens is measured in
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Diopters
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Diopters is equal to
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Reciprocal of focal distance in Meters
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Emmetropia
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Normal; light focuses on retina
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Hypertropia
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Farsighted; light focuses behind the retina
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Hypertropia is corrected with
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Convex lens
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Myopia is
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Nearsighted; light focuses in front retina
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Myopia is corrected with
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Biconcave lens
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Astigmatism is
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Irregular Curvature of the lens
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Astigmatism is corrected with
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Cylindric lens
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Presbyobia is a result of
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Loss of accomodation power of the lens occur with aging
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In presbyopia, the near point moves and corrected with
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further from the eye
Convex lens |
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Pigment layers of the retina absorb
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Stray light and prevent scatter of light
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Layer that converts 11-cis retinal to all trans retinal
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Pigment epithelial layer
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Rods and cones are not present on
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The optic disk; ie blind spot
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The ______ cells synapse on bipolar cells; the bipolar cells then synapse on _______
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Rods and cones cells
Ganglion cells |
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The basis for high acuity and low sensitivity of cones is
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Few cones synapse on single bipolar cells
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Where is the highest visual acuity and what is the ratio?
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The fovea; ratio 1:1 bipolar:cones
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What is the reason for less acuity and and greater sensitivity seen in the rods?
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Many rods synapse on single bipolar cell; light striking any one of the rods will synapse on the bipolar
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Are the output cells of the retina
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Ganglion cells
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What form the optic nerve?
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Ganglion cells' axons
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In presbyopia, the near point moves and corrected with
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further from the eye
Convex lens |
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Pigment layers of the retina absorb
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Stray light and prevent scatter of light
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Layer that converts 11-cis retinal to all trans retinal
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Pigment epithelial layer
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Rods and cones are not present on
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The optic disk; ie blind spot
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The ______ cells synapse on bipolar cells; the bipolar cells then synapse on _______
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Rods and cones cells
Ganglion cells |
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The basis for high acuity and low sensitivity of cones is
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Few cones synapse on single bipolar cells
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Where is the highest visual acuity and what is the ratio?
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The fovea; ratio 1:1 bipolar:cones
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What is the reason for less acuity and and greater sensitivity seen in the rods?
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Many rods synapse on single bipolar cell; light striking any one of the rods will synapse on the bipolar
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Are the output cells of the retina
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Ganglion cells
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What form the optic nerve?
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Ganglion cells' axons
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Axons of the ganglion cells for the optic tract and end in the
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Lateral geniculate body of thalamus
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What fibers of the cross in the optic chiasm and what fibers remain ipsilateral?
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The nasal hemiretina cross while the temporal fibers remain ipsilateral
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The right optic tract is composed of _____ and synapse in the ______ tract
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Left nasal hemiretina and
Right temporal hemiretina Synpase in Right lateral genicualte |
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What is the geniculocalcarine tract?
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Fibers from the lateral geniculate that pass posterior to the occipital lobe of the cortex
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Cutting the optic nerve causes
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Blindness on the same side
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Cutting the optic chiasm causes
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Heteronymous bitemporal hemianopia
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Axons of the ganglion cells for the optic tract end in the
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Lateral geniculate body of thalamus
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What fibers of the cross in the optic chiasm and what fibers remain ipsilateral?
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The nasal hemiretina cross while the temporal fibers remain ipsilateral
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The right optic tract is composed of _____ and synapse in the ______ tract
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Left nasal hemiretina and
Right temporal hemiretina Synpase in Right lateral genicualte |
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What is the geniculocalcarine tract?
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Fibers from the lateral geniculate that pass posterior to the occipital lobe of the cortex
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Cutting the optic nerve causes
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Blindness on the same side
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Cutting the optic chiasm causes
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Heteronymous bitemporal hemianopia
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Visual Aide
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Homonymous Contralateral Hemianopia; results from a lesion in optic tract
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Visual
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Rhodopsin belongs to what family of receptors?
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G-protein coupled receptors
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Rhodopsin is
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the photosensitive element; opsin = protein and retinal = aldehyde of Vit.A
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Light in the retinal converts ____ to ____.
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11-cis retinal to all-trans retinal
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Thru a series of steps ______ product is formed which activates trasnducin
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Metarhodopsin II
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Why is vit. A necessary for the visual pathway?
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Regeneration of 11-cis retinal.
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Metarhodopsin II signaling:
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Metarhodopsin activates G-protein transducin which then activates phospodiesterase
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Phosphodiesterase role in the visual pathway is
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1.Catalyzes the conversion of cGMP to 5'GMP; decreases cGMP.
2. ↓cGMP causes closure of Na+ channels; causing hyperpolarization 3.Hyperpolarization, leads to DECREASED RELEASE OF EITHER EXCITATORY OR INHIBITORY NEUROTRANSMITTERS |
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Increasing light intensity causes an increase
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hyperpolarization
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Three cotrical cell type are involved in shape and orientation and they are:
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Simple cells
Complex cells Hypercomplex cells |
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The Simple cells of visual cortex are involved in
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Correct position and orientation
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The complex cells of the visual cortex are involved in
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moving bars or edges of light with correct orientation
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The hypercomplex cell of the visual cortex respond to
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Lines of length and curves and angles
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An opacity that forms in the lens
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Cataracts
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Tx for Cataracts
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Removal of lens and artificially implant a lens
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Intraocular pressures are extremely high which can lead to optic nerve compression
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Glaucoma
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