Non-contact<i>in vivo</i>measurement of ocular microtremor using laser speckle correlation metrology

Kenny, Emer; Coakley, Davis; Boyle, Gerry

doi:10.1088/0967-3334/35/7/1229

Cited by 5 publications

(3 citation statements)

References 27 publications

(36 reference statements)

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“…Some researchers explain this relationship in terms of similarity in tissue constitutions; the cornea, lamina cribrosa and peripapillary sclera have biomechanical properties in common[ 15 – 18 ], and consequently, a higher CH may somehow represent a more energy-dissipative structure at the optic nerve head. Considering recent studies that revealed eyes receive daily incessant stress in the form of ocular microtremors[ 19 ], pulsatility[ 20 ], blinking,[ 21 , 22 ] and general eye movements,[ 23 , 24 ] we hypothesize in the current study that external stress that occurs repeatedly within a short period of time contribute to glaucomatous change by giving excessive energy load to the optic disc. When external stresses are placed on an eyeball, some energy is absorbed by the damping capacity of an eye, but the remaining unabsorbed energy can be a stress on the posterior segments of an eye, including the structures around the optic nerve head, which can cause damage to the axons and eventually the retinal ganglion cells.…”

Section: Introductionmentioning

confidence: 99%

Correlation between elastic energy stored in an eye and visual field progression in glaucoma

Aoki

Murata

Nakakura³

et al. 2018

PLoS ONE

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PurposeTo investigate whether the elastic energy stored in an eyeball at highest concavity (highest concavity energy; HCE), calculated with Corivs ST (CST, OCULUS), correlates with glaucomatous visual field (VF) progression.Methods108 eyes from 70 primary open angle-glaucoma patients were studied. The HCE was calculated using CST parameters. For each eye, the mean total deviation (mTD) of the 52 test points in the 24–2 Humphrey Field Analyzer test pattern was calculated and the mTD progression rate was determined from eight reliable VFs. Eyes were subdivided into: subgroups with low- or high-whole eye motion maximal length (WEM-d) and subgroups with short- or long-time taken to reach WEM-d (WEM-t), as measured with CST. The associations between mTD progression rate and HCE and other ocular/systemic parameters including age, Goldmann applanation tonometry based-intraocular pressure [GAT-IOP], and corneal hysteresis [CH] from the Ocular Response Analyzer (ORA®, Reichert) were investigated using the linear mixed model. The optimal model to describe mTD progression rate was selected from all possible combinations according to the second order bias corrected Akaike Information Criterion index.ResultsOptimal models to describe mTD progression rate included: CH in the model for all eyes, age and HCE in the model for the WEM-d low group, HCE in the model for the WEM-t short group, mean GAT-IOP in the model for the WEM-d high group, and age in the model for the WEM-t long-group.ConclusionsHCE was associated with glaucomatous VF progression in eyes with minimal whole eye motion (low WEM-d and WEM-t subgroups).

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Section: Introductionmentioning

confidence: 99%

Correlation between elastic energy stored in an eye and visual field progression in glaucoma

Aoki

Murata

Nakakura³

et al. 2018

PLoS ONE

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“…4 OMT frequencies have been extracted using a zero crossing analysis of the detected temporal signal. [5][6][7] OMT is caused by constant activity of the oculomotor units in the reticular formation of the brain. 4 Tone or tension of the extraocular muscles, which control eye movements, is achieved by a constant stream of neural impulses.…”

Section: Introductionmentioning

confidence: 99%

“…However, similar laser safety considerations as in the case of the speckle interferometric technique must be adhered to when using speckle imaging while attempting to measure OMT. 7,33,34 In the 1950s, researchers in the Kodak Eastman company measured both the amplitude and frequency of OMT (Ref. 35) in one direction.…”

Section: Introductionmentioning

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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Ocular microtremor: a structured review

Graham,

Das,

Vitorio

et al. 2023

Exp Brain Res

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Ocular microtremor (OMT) is the smallest of three involuntary fixational micro eye movements, which has led to it being under researched in comparison. The link between OMT and brain function generates a strong rationale for further study as there is potential for its use as a biomarker in populations with neurological injury and disease. This structured review focused on populations previously studied, instrumentation used for measurement, commonly reported OMT outcomes, and recommendations concerning protocol design and future studies. Current methods of quantifying OMT will be reviewed to analyze their efficacy and efficiency and guide potential development and understanding of novel techniques. Electronic databases were systematically searched and compared with predetermined inclusion criteria. 216 articles were identified in the search and screened by two reviewers. 16 articles were included for review. Findings showed that piezoelectric probe is the most common method of measuring OMT, with fewer studies involving non-invasive approaches, such as contact lenses and laser imaging. OMT frequency was seen to be reduced during general anesthesia at loss of consciousness and in neurologically impaired participants when compared to healthy adults. We identified the need for a non-invasive technique for measuring OMT and highlight its potential in clinical applications as an objective biomarker for neurological assessments. We highlight the need for further research on the clinical validation of OMT to establish its potential to identify or predict a meaningful clinical or functional state, specifically, regarding accuracy, precision, and reliability of OMT.

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Non-contactin vivomeasurement of ocular microtremor using laser speckle correlation metrology

Cited by 5 publications

References 27 publications

Correlation between elastic energy stored in an eye and visual field progression in glaucoma

Correlation between elastic energy stored in an eye and visual field progression in glaucoma

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

Ocular microtremor: a structured review

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