Eye Movements Flashcards
(18 cards)
Saccades
Rapid, in order to explore surroundings
Observer unaware
Happen when an object moves too fast for smooth pursuit
Saccadic masking
When your eye flicks from one object to another without blur
During rapid eye movements the brain interrupts processing
Smooth pursuit
Occurs when tracking an object moving relatively slowly, eyes follow it without interruption
Vergence
Converge inwards, diverge outwards
Occurs when an object gets closer, further away
Vestibulo-ocular reflex function
It stabilizes vision by moving the eyes in the opposite direction of head movement.
Which body system detects head movements for the VOR?
The vestibular system in the inner ear.
What happens to the eyes if you turn your head to the left?
The eyes move to the right to maintain focus on a target.
Why is the VOR important?
It prevents blurry vision during head movements and helps maintain balance.
Role of the inner ear in vestibulo-ocular reflex
Balance organ is located in the inner ear
Three semicircular canals detect head movements through liquid displacement
Sensory hair cells bend in response, triggering eye adjustment
Optokinetic reflex function
Triggered by moving objects in the environment.
Combines smooth pursuit and fast repositioning when the object moves out of view
Nystagmus
Prolonged, unidirectional OKR or VOR can cause this
Seen when watching passing trees, spinning in a chair
Accommodation
Not an eye movement
Focuses the eye on the object of interest and thereby helps create a sharp retinal image
The eye accommodates for slope vision by tightening the ciliary muscles, allowing the pliable crystalline lens to become more rounded
Electrooculography - what is it
Records eye movements using electrodes placed on the skin near the eyes
Measures the voltage difference between the cornea and retina as the eye moves
Key factors affecting EOG
Angle through which the eye moves
Light intensity and eye adaptation
EOG emplitude is greater in light than in darkness due to changes in retinal pigment epithelium potential
Applications of EOG
Eye movement tracking
REM sleep detection
Neurological diagnostics
Ophthalmology
Hand free tech
Keyboard and mouse control
Wheelchair navigation
Other assistive devices
Eye tracking types
Desk based, screen based = fixed setups for controlled environments
Mobile, wearable = advanced, used in natural settings
How do eye trackers work
Use cameras to track pupil movements
Mobile eye trackers also record scene footage
Calibration
Gaze direction
Key metrics of eye trackers
Number of fixations in specific areas
Average fixation duration per target
Total fixation time in an area
