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Block 12 Eye physiology

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klau253's version from 2017-05-28 12:41

Eye

Question Answer
Fibrous layercornea and sclera
vascular layeriris, ciliary body, choroid
Neural layerretina includes macula, fovea, optic disc
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Eye movements

 

Question Answer
Vestibulo-ocularinitiated by vestibular mechanism during rapid head movement, conjugate, gaze stabilisation
Optokineticinitiated by visual mechanism during slow head movement, conjugate, gaze stabilisation
Saccadedirects eyes toward visual target, conjugate, gaze shifting
Smooth pursuitfollows moving visual target, conjugate, gaze shifting
Vergenceadjust eyes for different viewing distance, disconjugate, gaze shifting
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Neual control of eye movements

Question Answer
Suplementary eye fielddecision and planning
Frontal eye fieldexecution
dIPFCdecision and planning
Post. parietal cortexvisuospatial integration, attention
caudate nucleus and substantia nigramodify motor commands from FEF
sup. colliculusmultisensory integration, target selection
reticular formationcoordination
brainstem nucleifinal common pathway
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neural control of pupil

Question Answer
Sympatheticsup. cervical ganglion --> carotid plexus --> ophthalmic nerve --> long ciliary nerve --> dilator iridis muscle
Parasympatheticoptic tract --> pretectal nucleus --> edinger-westphal --> oculomotor --> ciliary ganglion --> short ciliary nerve --> sphincter pupillae muscle
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Cataracts
Question Answer
RFsmoke, DM, trauma, age, radiation
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Glaucoma
Question Answer
RFsteroids, increased IOP(>22), HTN, severe myopia
Primary open-anglecommon, chronic, clogged trabecular meshwork, begins with loss of peripheral vision
Acute angle-closureuncommon, emergency, narrow ant. chamber angle, vision loss, headache, eye pain, nausea
Txbeta-blocker, alpha2 agonist, prostaglandin analogues, muscarinic agonist, carbonic anhydrase inhibitor
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Colour blindness
Question Answer
protanopeslack red cones
dueteranopeslack green cones
tritanopeslack blue cones
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Lateral geniculate nucleus
Question Answer
Magnocellularlarge cells in bottom 2 layers, receives from A ganglion cells, responsible for brightness change
Parvocellularsmall cells in top 4 layers, receives from B ganglion cells, responsible for colour change
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Extrastriate visual areas
Question Answer
V5 lesiondifficulty perceiving motion (akinetopsia)
V4 lesiondifficulty perceiving colour (acrhomatopsia)
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Geniculo-striate visual pathway
Question Answer
Where pathwayretina --> LGN --> Magnocellular --> V1 --> dorsal stream --> post. parietal cortex
if damagedoptic ataxia, cant guid motor movements using visual information
What pathwayretina --> LGN --> Parvocellular --> V1 --> ventral stream --> infero-temporal cortex
if damagedvisual agnosia, can't recognize virtually presented objects
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