physiology of the eye 3 Flashcards
what are the stages required to see an object?
- pattern of objects must fall on rods and cones in retina -> accommodation
- amount of light entering eye must be regulated
- energy from waves of photons must be transduces into electrical signals
- brain must receive and interpret signals
what is the retina divided into?
nasal and temporal
in the middle cranial fossa, what do optic nerves from each eye unite to form?
optic chiasm
nerve fibres from which half of the retina cross over at optic chiasm?
nasal
what does the left optic tract contain?
fibres from left temporal (lateral) retina and right nasal (medial) retinal
what does the right optic tract contain?
fibres from the right temporal retina and left nasal retina
where does each tract travel to?
its corresponding cerebral hemisphere to reach lateral geniculate nucleus (LGN)
where is the lateral geniculate nucleus located?
thalamus
axons from LGN carry visual info via which pathway?
optic radiation pathway
what can the optic radiation pathway be divided into?
upper optic radiation
lower optic radiation
(right and left)
where does the upper optic radiation carry fibres from and through?
from - superior retinal quadrants (corresponding to inferior visual field quadrants)
through - parietal lobe to reach visual cortex
where does lower optic quadrant carry fibres from and through?
from - inferior retinal quadrants (corresponding to superior visual field quadrant)
through - temporal lobe to reach visual cortex
where is information from both eyes combined?
layer 4 of primary visual cortex (V1)
where do cells outside of layer 4 receive input from?
both eyes
what are congenital cataracts?
people who are born with cataracts (opaque covering of lens) and have impaired vision
what is amblyopia (cortical blindness)?
visual disorders where there is no problem with the eye (optic and retina fine) but one eye has better vision than the other
what can amblyopia be caused by if not corrected in infancy?
strabismus (wandering eye)
