Compact portable ocular microtremor sensor: design, development and calibration

Ryle, James P.; Al-Kalbani, Mohammed; Collins, Niamh; Gopinathan, Unnikrishnan; Boyle, Gerry; Coakley, Davis; Sheridan, John T.

doi:10.1117/1.3083435

Cited by 10 publications

(4 citation statements)

References 29 publications

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“…If it is deterministic, e.g., vibration assessment [4], the statistical criterion is sufficient, as errors can be compensated by fitting the results to the expected path. If, on the other hand, the trajectory is completely unknown or is known to be erratic [6], the most conservative error should be used.…”

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confidence: 99%

Resolution limits to object tracking with subpixel accuracy

2012

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Subpixel methods increase the accuracy and efficiency of image detectors, processing units, and algorithms and provide very cost-effective systems for object tracking. Published methods achieve resolution increases up to three orders of magnitude. In this Letter, we demonstrate that this limit can be theoretically improved by several orders of magnitude, permitting micropixel and submicropixel accuracies. The necessary condition for movement detection is that one single pixel changes its status. We show that an appropriate target design increases the probability of a pixel change for arbitrarily small shifts, thus increasing the detection accuracy of a tracking system. The proposal does not impose severe restriction on the target nor on the sensor, thus allowing easy experimental implementation.

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confidence: 99%

Resolution limits to object tracking with subpixel accuracy

2012

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“…6 Recently, accurate noncontact optical methods employing speckle interferometric techniques have been devised specifically to measure OMT. 6,32 However, the resulting sensors only measure in-plane motion along one direction axis in one eye. Furthermore, they must adhere rigorously to strict safety standards in order to avoid laser damage to the retina.…”

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confidence: 99%

Simultaneous drift, microsaccades, and ocular microtremor measurement from a single noncontact far-field optical sensor

2015

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We report on the combined far-field measurement of the three involuntary eye movements, drift, microsaccades, and ocular microtremor (OMT), using a noncontact far-field optical method. We review the significance of the smallest and least measured, and thus least understood, of the three, OMT. Using modern digital imaging techniques, we perform detailed analysis, present experimental results, and examine the extracted parameters using a noncontact far-field sensor. For the first time, in vivo noncontact measurements of all fixational in-plane movements of the human eye are reported, which simultaneously provide both the horizontal (left-right) and vertical (up-down) displacement results.

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“…Thus, studies focusing on OMT are rare and the perceptual consequences of OMT are virtually unknown. New noncontact methods to measure OMT are in development, but not yet ready for widespread use (Ryle et al, 2009). Such technology may facilitate future studies to uncover OMT’s role in vision.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous recordings of ocular microtremor and microsaccades with a piezoelectric sensor and a video-oculography system

McCamy

Collins

Otero‐Millan

et al. 2013

PeerJ

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Our eyes are in continuous motion. Even when we attempt to fix our gaze, we produce so called “fixational eye movements”, which include microsaccades, drift, and ocular microtremor (OMT). Microsaccades, the largest and fastest type of fixational eye movement, shift the retinal image from several dozen to several hundred photoreceptors and have equivalent physical characteristics to saccades, only on a smaller scale (Martinez-Conde, Otero-Millan & Macknik, 2013). OMT occurs simultaneously with drift and is the smallest of the fixational eye movements (∼1 photoreceptor width, >0.5 arcmin), with dominant frequencies ranging from 70 Hz to 103 Hz (Martinez-Conde, Macknik & Hubel, 2004). Due to OMT’s small amplitude and high frequency, the most accurate and stringent way to record it is the piezoelectric transduction method. Thus, OMT studies are far rarer than those focusing on microsaccades or drift. Here we conducted simultaneous recordings of OMT and microsaccades with a piezoelectric device and a commercial infrared video tracking system. We set out to determine whether OMT could help to restore perceptually faded targets during attempted fixation, and we also wondered whether the piezoelectric sensor could affect the characteristics of microsaccades. Our results showed that microsaccades, but not OMT, counteracted perceptual fading. We moreover found that the piezoelectric sensor affected microsaccades in a complex way, and that the oculomotor system adjusted to the stress brought on by the sensor by adjusting the magnitudes of microsaccades.

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Compact portable ocular microtremor sensor: design, development and calibration

Cited by 10 publications

References 29 publications

Resolution limits to object tracking with subpixel accuracy

Resolution limits to object tracking with subpixel accuracy

Simultaneous drift, microsaccades, and ocular microtremor measurement from a single noncontact far-field optical sensor

Simultaneous recordings of ocular microtremor and microsaccades with a piezoelectric sensor and a video-oculography system

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