Evaluation of Balance
John C Watkinson, Raymond W Clarke, Christopher P Aldren, Doris-Eva Bamiou, Raymond W Clarke, Richard M Irving, Haytham Kubba, Shakeel R Saeed in Paediatrics, The Ear, Skull Base, 2018
Saccades are fast movements of the eyes (200–500 degrees per second) which allow us to shift gaze from one object of interest to another. Unlike smooth pursuit movements, that do require a visible moving target, saccades can be generated at will or command without a specifically defined target. These refixations occur incessantly so that gross saccadic defects are often detected while interrogating the patient. It should be said at the outset that just saying that a patient has abnormal saccades is not sufficient to make a topographic diagnosis; there are three independent properties of saccades to be clinically assessed: velocity (normal, slow or absent saccades, i.e. a gaze palsy), accuracy (normo-, hypo- or hypermetric) and binocular conjugacy (conjugate or dysconjugate, e.g. as in internuclear ophthalmoplegia).
Smart Eye Tracking Sensors Based on Pixel-Level Image Processing Circuits
Iniewski Krzysztof in Integrated Microsystems, 2017
Saccades are the rapid eye movements occurring when we look around to examine our environment. Saccadic eye movements can vary considerably in magnitude, from less than 1° to more than 100° as the situation demands. The peak velocity during the movement depends on the size of the saccade. For large saccades it can reach 800°/s. because the velocity is so high, the movements are brief. The most frequently occurring saccades, which are smaller than 15°, take less than 50 ms from start to finish. Saccades are voluntary eye movements in the sense that we can consciously choose to look, or ignore, things in the visual scene. Once initiated, however, the execution of the movement is automatic. During the eye movement, when the retinal image is sweeping rapidly across the retina, vision is actively suppressed.
Can Cognitive Theories Help to Understand Motor Dysfunction in Autism Spectrum Disorder?
Elizabeth B. Torres, Caroline Whyatt in Autism, 2017
Eye movements serve to maintain objects of interest on the fovea, the region of the retina that provides the greatest acuity and color detection (Leigh and Zee 2015). Accurate eye movements are essential for on-line regulation of fine and gross motor accuracy, in addition to proprioceptive signals, and also for providing visual feedback to refine movement accuracy over the long term. Saccades are semiballistic eye movements that shift the eye toward an object of interest, while smooth pursuit eye movements help us to track moving objects, while either an object or ourselves (or both) are in motion (Leigh and Zee 2015). These two main types of eye movements help us to plan actions and coordinate our whole-body movements, and give us visual information about our changing environment to enable us to adapt our actions on the fly. There are a number of known visual processing and ocular motor disturbances in ASD that are likely to impact these processes, which include impaired motion detection (Manning et al. 2013; Takarae et al. 2014), inaccurate eye movements (Takarae et al. 2004a, 2004b; Johnson et al. 2012; Schmitt et al. 2014), and inefficient timing of ocular motor with fine motor actions (Crippa et al. 2013).
The Effect of Target Velocity on the Fast Corrective Response during Reaching Movement
Published in Journal of Motor Behavior, 2022
Kosuke Numasawa, Tomohiro Kizuka, Seiji Ono
With regard to eye movements, a target jump stimulus induces saccades while a target motion stimulus induces smooth pursuit. Although both eye movements play an important role in holding the visual image on the fovea, these are driven by different visual information. Saccades are driven by the retinal position error between eye and target position (Krauzlis et al., 2000), whereas smooth pursuit is driven by the retinal velocity error (retinal slip) between eye and target motion (Krauzlis, 2004; Lisberger, 2010; Ono, 2015). Furthermore, these eye movements have different latencies, as saccade latency is about 150-200 ms (Leigh & Zee, 2015) while pursuit latency is about 120-140 ms in human subjects (Krauzlis et al., 1999; Lindner & Ilg, 2000; Miyamoto et al., 2020). Since these eye movements are based on different control systems, the fast corrective response to the target motion may have different properties from the response to the target jump.
Assessing sustained attention of children with ADHD in a class flow video task
Published in Nordic Journal of Psychiatry, 2022
Esen Yıldırım Demirdöğen, İbrahim Selçuk Esin, Bahadır Turan, Onur Burak Dursun
The eye-tracking device uses infrared light technology to track the participant’s eye movements, such as fixations (the stabilization of the eye on part of a stimulus for a period of time), saccades (eye movements between fixations), and blinks. The SMI RED250 eye tracker was used in the present study. As a stimulus is needed to employ an eye-tracking device, a visual stimulus (a video task) was presented using Experiment Center software. Eye movement data were recorded with iViewX. The parameters of eye movements, such as fixation and saccade, were measured via Be Gaze software, which also enabled the identification of areas of interest (AOI) on the presented stimulus. In this way, fixation, saccade, and related eye-tracking parameters in a given area of the stimulus can be measured.
Evaluation of saccadic velocity in patients with orbital floor fracture before and after surgery
Published in Seminars in Ophthalmology, 2022
Ken Kakeue, Masanobu Kanazawa, Tatsuya Yunoki, Miharu Mihara, Atsushi Hayashi
Saccades play an important role in the rapid movement of eyes to visual targets. The saccadic PV is reported to be an important parameter for saccadic evaluation,18,19 and the examination of the saccadic PV using an eye tracking system can measure dynamic ocular motility. However, to the best of our knowledge, there are no reports of a detailed evaluation of saccades before and after surgery in patients with orbital floor fractures. In the present patient series, the non-injured eyes did not show any significant difference in saccadic PV between before and after surgery. On the other hand, in the injured eyes, there was no significant difference in downgaze, adduction, or abduction, but improvement was observed in upgaze vision. We believe that saccade PVs may be a useful method of assessing eye movements in patients with orbital floor fracture. Additional studies are needed to evaluate the usefulness of the measurement of saccade PVs.
Related Knowledge Centers
- Blinking
- Eye Movement
- Fixation
- Fovea Centralis
- Frontal Eye Fields
- Rapid Eye Movement Sleep
- Retina
- Smooth Pursuit
- Superior Colliculus
- Optokinetic Response