VIsual reflexes Flashcards
what occurs in the pupillary reflex
when light is shone in one eye, both pupils constrict
what are the pupils different reactions to light
too much light = constricts
not enough light = dilates
what is another name for the pupillary reflex
consentual reflex (occurs in both eyes when one is stimulated)
what would cause the absense of the pupillary reflex
damage to nerves or reflex circuits
what is involved in a visual reflex
complex network of neural structures
what is the ciliary / accomodation reflex
reflexively adjust the thickness of the lens to maintain image focus
what is the difference between accomdated and unaccomodated
accomodated = looking at something close (lens thickens, ciliary muscles contract)
unaccomodated = looking at something distant (lens thins, ciliary muscles relaxed)
hwo do ciliary muscles and zonular fibres work together
relaxation of ciliary muscles = tension in zonular fibres (pulls lens thinner)
contraction of ciliary muscles = relaxes the zonualr fibres (lens becomes thick / natural shape)
what is vergence
reflexive convergence / divergence of the eyes
what is vergence used for
helps reduce blurriness and double vision
can also be used for smooth pursuit of objects that are moving in the depth plane
what occurs during vergence
eyes move in or out towards the midline depending on how far away the object is from our face
what are saccades
when our eyes jump from one focus point to another
(not an even firing rate)
what is gaze movement
sum of head and eye movement
- results in larger visual field
how is smooth pursuit measured
in degrees/sec
- more degrees/sec = moving faster across the visual field)
how does smooth pursuit work with low velocity movement
- initial catch up saccade
- then smooth pursuit follows
how does smooth pursuit work with high velocity movement
- multiple catch up saccades are necessary
- may not be able to track across visual field
what is optic flow
systematic mvmt of visual info when we move relative to objects and when objects move relative to us
what is FRO (focus of radial outflow)
focus flows out across visual field as we get closer to it (takes up more the visual field)
- target grows or shrinks depending on mvmt
what is TTA (time of arrival)
time remaining before a specific point or part of moving object reaches a designated fixed spatial location
(ex: walking through a door, hitting a baseball)
what type of visual cue is TTA
monocular visual cue
- don’t need both eyes
