Visual System Flashcards
image on the retina is _____ and _____
inverted and reversed
central fixation point is on the
fovea
blind spot is where…
optic nerve attaches
nearsightedness is called
myopia
myopia eye length
longer than normal
myopia hits light where on retina?
in front of
farsightedness is called
hyperopia
hyperopia light focus is where on retina?
behind the retina
eye length for hyperopia?
eye is shorter than normal
when you see blurry and distorted images
astigmatism
cornea is shaped as what in astigmatism?
football
retina is made up of whAT?
rods and cones
bipolar cells
deepest retinal layer
photoreceptors
rods and cones
intermediate retinal layer
information integrating neurons
bipolar cells
Works at low levels of illumination, insensitive to color, limited resolution
scotopic rod
Works at high levels of illumination, responsible forcolor vision, sharp vision, and acuity
photopic cone
dark light, whats activated?
rods
bright light, whats activated?
cones
cones are densest where
macula lutea
cones have keenest vision where
fovea
rods contain what protein pigment?
rhodopsin
Three different types of cones with pigment sensitiveto either
blue, green, or red wavelengths
(Deuteranopia/Protanopia)
red/green color blindness
(Tritanopia)
blue yellow color blindness
Achromatopsia
condition of no cones- ONLY RODS
Information-integrating neurons that exit eyeball as the optic nerve
ganglion cells in retina
ganglion cells are located in what layer?
superficial layer
Circular, elevated region where ganglion cell
axons gather to leave the eye as the optic nerve
optic disk (blind spot)
step 1:
Cells in retina convert light into
neural signals
step 2:
Signals processed in retina and conveyed to
retinal output cells
step 3:
Retinal output conveyed by axons that travel in
optic nerve
optic chiasm
optic tract
step 4:
Axons synapse in ________ of the thalamus
lateral geniculate nucleus
step 5:
From thalamus neurons travel in the?
within?
to?
optic radiations
internal capsule
primary visual cortex
_______ signals cross midline at the optic chiasm projecting to contralateral
visual cortex.
nasal retina
_________ signals continue ipsilaterally to project to the ipsilateral
cortex
temporal retina
random black spot on right eye
monocular scotoma
one eye black
monocular vision loss
outside/sides white
bitemporal hemianopia
same side of both eyes black
contralateral homonymous hemianopia
upper 1/4 of same sides both eyes blocked
contralateral superior quadrantopia
Retrochiasmal lesions - lesions of optic tracts, LGN, optic radiations, or visual cortex cause
homonymous hemianopia
homonymous hemianopia
Causes include retinal infarcts, hemorrhage, degeneration, or infection.
monocular scotoma
Causes: glaucoma, optic neuritis, elevated
intracranial pressure, optic glioma, schwannoma, menigioma, or trauma
monocular vision loss
Damage to the optic chiasm
Visual loss more typically asymmetric than is seen in diagram.
Common lesions: pituitary adenoma, menigioma
bitemporal hemianopia
Caused by lesions of the temproal lobe leading toinfarcts in the optic radiations
“pie in the sky” defect
contralateral superior qudrantanopia
Lesion in the parietal lobe cause interruptions in the upper portions of the optic radiations
“pie on the floor” defect
contralateral inferior quadrantonopia
An opacity of the lens resulting in decreased
acuity; vision hazy overall, particulary in glaring light
catarct
what vision loss does NOT impact field of vision
cataract
scotoma in cataract?
NO
The deterioration of the macula, the central areaof the retina
- central scotoma
- side vision is fine
macular degeneration
The leaking of retinal blood vessels may occur inadvanced or long-term diabetes; affects the
macula or the entire retina and vitreous.
diabetic retinopathy
patchy scotoma
diabetic retinopathy
chronic elevated eye pressure causes optic nerve atrophy and loss of peripheral vision
glaucoma
can only see the middle
black on outside (scotoma)
glaucoma
Congenital degeneration of the pigmented layerof the retina leads to a severe loss of peripheral
vision.
retinitis pigmentosa
only a small part of middle vision can be seen, most of everything around is scotoma
retinitis pigmentosa
Constriction of pupil due to
parasympathetic innervation
Dilation of pupil due to
sympathetic innervation
Functions to maintain the position of the eyes so
that the image of the object of interest is kept on the fovea of both eyes
- move your head and fovea but you stay fixed on the object
fixation reflex
Occurs when gaze is shifted from a distant object to a near one
- looking from projector to ipad
near reflex
denotes pupillary size inequality
aniscoria
Axons of the retinal ganglion cells that project tothe pretectal area
afferent limb
Interneurons of the pretectal area that terminate bilaterally in the Edinger-Westphal nuclei of the
oculomotor complex
reflex center
inflammatory demyelinating disorder often relatedto multiple sclerosis
Symptoms of eye pain, decreased acuity, and
impaired color vision
Recovery is common
optic neuritis
Optic disc swelling associated with elevatedintracranial pressure
papilledema
Vascular lesions of the occipital lobe
Both MCA and PCA nourish the cortical area representing the macula
macular sparing
can perceive, but cannot understand meaning of what they see
visual agnosia
Bilateral lesion of specific area of visual cortex
cortical blindness
Face blindness
prosopagnosia
prosopagnosia occurs to which cortex?
Damage to occipitotemporal cortex
what are the 4 functions of the eye?
1] regulate amount of light
2] focus on objects near and far
3] maintain balance between regulation and focus
4] record pattern of incoming light
