Visual pathway Flashcards
What is your visual field?
Everything you see around you with one eye
What is considered to be your physiological ‘blindspot’?
optic nerve head (where optic nerve starts off)
you have no rods or cones here
What is your fovea?
It is the thinnest part of retina (fewest layers of retina)– only has cones –
these cones are as close to surface as possible so you detect light more efficiently - this is where you see the best (best visual acuity)
if you want to see something more clearly - you move your eyes so the image of the object falls on the fovea
How do you test someone’s visual field?
confrontation test (outpatient screening) or automated perimetry
Describe the confrontation test
having the patient looking directly at your eye or nose and testing each quadrant in the patient’s visual field by having them count the number of fingers that you are showing
test one eye at a time
Describe automated perimetry
You sit and look inside a bowl-shaped instrument called a perimeter.
While you stare at the centre of the bowl, lights flash. You press a button each time you see a flash.
What is a visual acuity test
Checks how well you see the details of a letter or symbol from a specific distance - this tests your fovea
How do images form on your retina?
Images of objects in your field of vision are formed upside down and inverted on your retina
Where do all fibres from the eye that pass through the optic nerve join at?
the optic chiasma
What crosses over to the opposite side at the optic chiasma?
the medial nasal fibres of both right and left visual fields
What part of the brain do the fibres go in to?
lateral geniculate body
Where do fibres travel to after reaching the lateral geniculate body
go as the optic radiation to the very back of your cerebral hemisphere to occipital lobe
The right visual cortex (within occipital lobe) sees which half of the visual field?
left and vice versa
what is bitermporal hemiopia?
temporal part of vision is lost
If the R optic nerve is damaged what is lost from your field of vision?
blindness in one eye
