Table of Contents
What is optokinetic system?
Optokinetic Eye Movements The optokinetic response (OKR) supports the vestibuloocular reflex (VOR) in maintaining stable gaze during constant-velocity or low-acceleration head movements by producing eye movements in the direction of visual motion. The optimal stimulus for producing an OKR is large-field visual motion.
What is optokinetic eye movement?
Optokinetic nystagmus is defined by a slow eye movement in the direction of a moving object and a rapid return of eye position in the opposite direction.
What is optokinetic stimulation?
A form of intervention for USN that involves the observation of moving visual targets to encourage visual scanning of the neglected hemispace.
What is optokinetic after nystagmus?
Optokinetic after-nystagmus (OKAN) is the nystagmus which is immediately observed in darkness after optokinetic stimulation has been stopped. Barany reported this nystagmus in 1907.
What is the eye movement test called?
The extraocular muscle function test is performed to evaluate any weakness, or other defect in the extraocular muscles which results in uncontrolled eye movements. The test involves moving the eyes in eight different directions in space to evaluate the proper functioning of the extraocular muscles of the eyes.
What does Okn stand for?
Optokinetic nystagmus (OKN) Optokinetic nystagmus, or OKN for short, is the eye movement elicited by the tracking of a moving field.
What is VOR testing for?
What is the VOR test? Vestibular-Ocular Reflex (VOR) test is used to diagnose the cause of recurrent vertigo (giddiness). VOR is a reflex eye movement that stabilizes images on the retina during head movement. VOR testing should be considered an important part of a group of tests that evaluate vertigo.
What is the purpose of the vestibulo-ocular reflex?
The Vestibulo-Ocular Reflex. The vestibulo-ocular reflex (VOR) uses information from the vestibular labyrinth of the inner ear to generate eye movements that stabilize gaze during head movements.
What is a DEM test?
The Developmental Eye Movement (DEM) test is a psychometric paper test for the assessment of eye movement performance in children. The quantification of eye movement is performed by naming numbers in a reading-like condition without sophisticated instruments.
What is the purpose of ocular motility test?
This test is performed to evaluate weakness or other problems in the extraocular muscles. These problems may result in double vision or rapid, uncontrolled eye movements.
What causes visual vertigo?
Visual vertigo is characterized by having vertigo symptoms that are triggered by visual stimuli. These symptoms can develop in individuals with a vestibular disorder (i.e. vestibular neuritis, Meniere disease. Benign paroxysmal positional l vertigo (BPPV), migraine).
How do you use Okn strip?
Tap the strips icon in the bottom toolbar to toggle the color of the strips between Red and Black. Pinch or Zoom with two fingers to change the width of the strips. Swipe against the direction the strips are moving to reverse their direction. Tap the screen with two fingers to hide or show the bottom toolbar.
How does VOR reflex work?
The vestibulo-ocular reflex (VOR) is a gaze stabilizing reflex: the sensory signals encoding head movements are transformed into motor commands that generate compensatory eye movements in the opposite direction of the head movement, thus ensuring stable vision.
What is optokinetic reflex in psychology?
Optokinetic Reflex. Optokinetic nystagmus is a rhythmic involuntary conjugate ocular movement in response to the movement of full visual field images, either rotation of an image before the subject, such as a drum with vertical black stripes on a white background, or rocking of a mirror back and forth in front of the patient’s eyes.
What is an abnormal optokinetic response?
Abnormal optokinetic responses An abnormal response seen in one direction but not the other is suggestive of a vestibular disorder. If not accompanied by spontaneous nystagmus, the disorder is likely central in origin. When the maximum speed of the slow phase velocity is less than 60% of the stimulus speed, it is outside of threshold limits.
How does the optokinetic reflex activate neck muscles?
The optokinetic reflex activates neck muscles in response to movement of the visual field over the retina.
What is the optokinetic signal used for?
Thus, the optokinetic signal serves two important purposes: It effects the OKR to assist the VOR and it provides the error signal for continually fine-tuning VOR gain. Vito Enrico Pettorossi, Pierangelo Errico, in Studies in Visual Information Processing, 1994