Development of a Magnetoresistive-Based Wearable Eye-Tracking System for Oculomotor Assessment in Neurological and Otoneurological Research—Preliminary In Vivo Tests

Over the past 20 years, several eye-tracking technologies have been developed. This article aims to present a new type of eye tracker capable of producing detailed information on eye and head movements using an array of magnetoresistive detectors fixed on the patient’s head and a small magnet inserted into a contact lens, adapted to the curvature of the cornea of the subject. The software used for data analysis can combine or compare eye and head movements and can represent them as 2D or 3D images. Preliminary data involve an initial patient who was asked to perform several tasks to establish the accuracy, reliability, and tolerance of the magnetic eye tracker and software. The tasks included assessment of saccadic eye movements and pursuit, “drawing” alphabetic shapes or letters, and reading. Finally, a Head Impulse Test (HIT) was performed to estimate the VOR gain, comparing the standard deviation established via vHIT with that established via this magnetic eye tracker (mHIT). This prototypical device is minimally invasive, lightweight, relatively cheap, and tolerable, with a high degree of reliability and precision. All these characteristics could lead to the future use of the magnetic eye tracker in neurological and otoneurological fields

A Wearable Wireless Magnetic Eye-Tracker, in-vitro and in-vivo tests

A wireless, wearable magnetic eye tracker is described and characterized. The proposed instrumentation enables simultaneous evaluation of eye and head angular displacements. Such a system can be used to determine the absolute gaze direction as well as to analyze spontaneous eye re-orientation in response to stimuli consisting in head rotations. The latter feature has implications to analyze the vestibulo-ocular reflex and constitutes an interesting opportunity to develop medical (oto-neurological) diagnostics. Details of data analysis are reported together with some results obtained in-vivo or with simple mechanical simulators that enable measurements under controlled conditions

Frequency-dependent tuning of the human vestibular "sixth sense" by transcranial oscillatory currents

Objective: The vestibular cortex is a multisensory associative region that, in neuroimaging investigations, is activated by slow-frequency (1-2 Hz) galvanic stimulation of peripheral receptors. We aimed to directly activate the vestibular cortex with biophysically modeled transcranial oscillatory current stimulation (tACS) in the same frequency range. Methods: Thirty healthy subjects and one rare patient with chronic bilateral vestibular deafferentation underwent, in a randomized, double-blind, controlled trial, to tACS at slow (1 or 2 Hz) or higher (10 Hz) frequency and sham stimulations, over the Parieto-Insular Vestibular Cortex (PIVC), while standing on a stabilometric platform. Subjective symptoms of motion sickness were scored by Simulator Sickness Questionnaire and subjects' postural sways were monitored on the platform. Results: tACS at 1 and 2 Hz induced symptoms of motion sickness, oscillopsia and postural instability, that were supported by posturographic sway recordings. Both 10 Hz-tACS and sham stimulation on the vestibular cortex did not affect vestibular function. As these effects persisted in a rare patient with bilateral peripheral vestibular areflexia documented by the absence of the Vestibular-Ocular Reflex, the possibility of a current spread toward peripheral afferents is unlikely. Conversely, the 10 Hz-tACS significantly reduced his chronic vestibular symptoms in this patient. Conclusions: Weak electrical oscillations in a frequency range corresponding to the physiological cortical activity of the vestibular system may generate motion sickness and postural sways, both in healthy subjects and in the case of bilateral vestibular deafferentation. Significance: This should be taken into account as a new side effect of tACS in future studies addressing cognitive functions. Higher frequencies of stimulation applied to the vestibular cortex may represent a new interventional option to reduce motion sickness in different scenarios

A Wearable Wireless Magnetic Eye-Tracker, in-vitro and in-vivo Tests

A wireless, wearable magnetic eye tracker is described and characterized. The proposed instrumentation enables simultaneous evaluation of eye and head angular displacements. Such a system can be used to determine the absolute gaze direction as well as to analyze spontaneous eye re-orientation in response to stimuli consisting in head rotations. The latter feature has implications to analyze the vestibulo-ocular reflex and constitutes an interesting opportunity to develop medical (oto-neurological) diagnostics. Details of data analysis are reported together with some results obtained in-vivo or with simple mechanical simulators that enable measurements under controlled conditions.Comment: 11 pages, 7 figures, 46 reference

An innovative eye-tracker: Main features and demonstrative tests

We present a set of results obtained with an innovative eye-tracker based on magnetic dipole localization by means of an array of magnetoresistive sensors. The system tracks both head and eye movements with a high rate (100–200 Sa/s) and in real time. A simple setup is arranged to simulate head and eye motions and to test the tracker performance under realistic conditions. Multimedia material is provided to substantiate and exemplify the results. A comparison with other available technologies for eye-tracking is drawn, discussing advantages (e.g., precision) and disadvantages (e.g., invasivity) of the diverse approaches, with the presented method standing out for low cost, robustness, and relatively low invasivity

Ligasure™ Impact and Ligasure™ Small Jaw in Body Contouring after Massive Weight Loss: A New Perspective

Background The most effective dissection technique for elevating flaps in body contouring is still controversial, particularly in high-risk massive weight loss (MWL) patients. LigaSure (Medtronic, Dublin, Ireland) is an energy device commonly used among different surgical specialties to reduce morbidity and improve outcomes. The aim of this study is to investigate the effectiveness of LigaSure Impact and LigaSure Small Jaw in body contouring after MWL compared with conventional technique. Material and methods Patients who underwent abdominoplasty, mastopexy, brachioplasty and thigh lift after MWL at a single center from 1 December 2018 to 1 March 2020 were retrospectively reviewed. In each procedure patients were divided into two groups according to the dissection technique: LigaSure group and monopolar electrosurgery group. Patients characteristics, perioperative details and postoperative complications were evaluated. Results Fourty-five patients underwent abdominoplasty, twenty-six mastopexy, twenty brachioplasty and sixteen medial thigh lift. Using LigaSure, operative time was longer in abdominoplasty and thigh lift, but shorter in mastopexy and brachioplasty. Although not statistically significant, the amount of blood and serum recorded from drains in the first 36 hours was reduced in LigaSure groups. Additional analgesic intake was reduced with LigaSure as well as postoperative subjective pain. In all body contouring procedures statistically significant difference was found in days of hospital stay favoring LigaSure groups. Complications occurred most frequently in control groups compared to LigaSure groups. Conclusion LigaSure Impact and LigaSure Small Jaw may be beneficial in improving outcomes because they might reduce fluids drainage, analgesics intake, hospital stay and postoperative complications