How we see Flashcards
rods function
sensitive
monochromatic
peripheral vision: distributed throughout retina
slow adaptation
poor acuity and resolution: many rods connected to one bipolar cell
cones function
poorly sensitive
colour vision (R,G,B)
near vision: found only in fovea + fewer
good accommodation + change in light (night vision)
good acuity and resolution: one cone to one bipolar cell
cause of night blindness
problem with cones
vit A def
retinal issues
cause of colour blindness
congenital (R-G)
optic neuropathy
photo transduction
converting light -> electrochemical impulses
right eye blindness
right optic nerve
bitemporal hemianopia
optic chiasm
right homonymous hemianopia
left optic tract - or injury to the left occipital lobe
visual pathway
light -> retina -> optic nerve -> optic chiasm -> optic tract -> LGN -> optic radiation -> visual cortex
- vision generated by photoreceptors (rods and cones) in retina
- signals gathered by ganglion cells in retina
- optic nerve
- optic chiasm
- optic tract
- LGN: axons synapse
- optic radiation: spread through deep white matter of the brain - some go through parietal, some temporal lobe
- primary visual cortex
causes of diplopia
extraocular muscles -> CN III, IV, VI
CN nuclei
brainstem
cerebellum failure effect on vision
loss of smoothness of eye movements
important parts of the eye to see
cornea lens retina optic nerve chiasm optic tract visual cortex
cornea fn
dust cover of eyes + filter UV light
light refraction
lens fn
suspended from ciliary body by ligaments
refraction (+ focus it on retina),
accommodation (changing of tension of ligs - allows image to be focused on the retina at diff distances)
visual defects
- presbyopia: difficulty reading, usually in elderly cause of increase rigidity of lens (long-sighted)
- cataract: caused by aging/trauma. insert intraocular lens
