scholarly journals Biometric Measurement of Anterior Segment: A Review

Sensors ◽  
2020 ◽  
Vol 20 (15) ◽  
pp. 4285
Author(s):  
Bin Liu ◽  
Chengwei Kang ◽  
Fengzhou Fang
Keyword(s):  
High Speed ◽  
Anterior Segment ◽  
Future Research ◽  
Basic Principles ◽  
Human Eye ◽  
In Vivo Measurement ◽  
Research Perspectives ◽  
Scattering Effects ◽  
Fine Resolution

Biometric measurement of the anterior segment is of great importance for the ophthalmology, human eye modeling, contact lens fitting, intraocular lens design, etc. This paper serves as a comprehensive review on the historical development and basic principles of the technologies for measuring the geometric profiles of the anterior segment. Both the advantages and drawbacks of the current technologies are illustrated. For in vivo measurement of the anterior segment, there are two main challenges that need to be addressed to achieve high speed, fine resolution, and large range imaging. One is the motion artefacts caused by the inevitable and random human eye movement. The other is the serious multiple scattering effects in intraocular turbid media. The future research perspectives are also outlined in this paper.

scholarly journals Static and Dynamic Error of a Biplanar Videoradiography System Using Marker-Based and Markerless Tracking Techniques

2011 ◽  
Vol 133 (12) ◽  
Author(s):  
Daniel L. Miranda ◽  
Joel B. Schwartz ◽  
Andrew C. Loomis ◽  
Elizabeth L. Brainerd ◽  
Braden C. Fleming ◽  
...  
Keyword(s):  
Systematic Error ◽  
Gold Standard ◽  
High Speed ◽  
Angular Displacement ◽  
High Accuracy ◽  
Tracking Algorithm ◽  
Future Research ◽  
Markerless Tracking ◽  
Standard Instrumentation

The use of biplanar videoradiography technology has become increasingly popular for evaluating joint function in vivo. Two fundamentally different methods are currently employed to reconstruct 3D bone motions captured using this technology. Marker-based tracking requires at least three radio-opaque markers to be implanted in the bone of interest. Markerless tracking makes use of algorithms designed to match 3D bone shapes to biplanar videoradiography data. In order to reliably quantify in vivo bone motion, the systematic error of these tracking techniques should be evaluated. Herein, we present new markerless tracking software that makes use of modern GPU technology, describe a versatile method for quantifying the systematic error of a biplanar videoradiography motion capture system using independent gold standard instrumentation, and evaluate the systematic error of the W.M. Keck XROMM Facility’s biplanar videoradiography system using both marker-based and markerless tracking algorithms under static and dynamic motion conditions. A polycarbonate flag embedded with 12 radio-opaque markers was used to evaluate the systematic error of the marker-based tracking algorithm. Three human cadaveric bones (distal femur, distal radius, and distal ulna) were used to evaluate the systematic error of the markerless tracking algorithm. The systematic error was evaluated by comparing motions to independent gold standard instrumentation. Static motions were compared to high accuracy linear and rotary stages while dynamic motions were compared to a high accuracy angular displacement transducer. Marker-based tracking was shown to effectively track motion to within 0.1 mm and 0.1 deg under static and dynamic conditions. Furthermore, the presented results indicate that markerless tracking can be used to effectively track rapid bone motions to within 0.15 deg for the distal aspects of the femur, radius, and ulna. Both marker-based and markerless tracking techniques were in excellent agreement with the gold standard instrumentation for both static and dynamic testing protocols. Future research will employ these techniques to quantify in vivo joint motion for high-speed upper and lower extremity impacts such as jumping, landing, and hammering.

Accommodation and presbyopia in the human eye 1: Evaluation of in vivo measurement techniques

1989 ◽  
Vol 28 (6) ◽  
pp. 1097 ◽  
Author(s):  
Jane F. Koretz ◽  
Paul L. Kaufman ◽  
Michael W. Neider ◽  
Patrick A. Goeckner
Keyword(s):  
Measurement Techniques ◽  
Human Eye ◽  
In Vivo Measurement

scholarly journals High Speed SD-OCT System Using GPU Accelerated Mode for in vivo Human Eye Imaging

2013 ◽  
Vol 17 (1) ◽  
pp. 68-72 ◽  
Author(s):  
Nam Hyun Cho ◽  
Unsang Jung ◽  
Suhwan Kim ◽  
Woonggyu Jung ◽  
Junghwan Oh ◽  
...  
Keyword(s):  
High Speed ◽  
Human Eye ◽  
Sd Oct

scholarly journals Direct Measurement and Modeling of Intraglottal, Subglottal, and Vocal Fold Collision Pressures during Phonation in an Individual with a Hemilaryngectomy

2021 ◽  
Vol 11 (16) ◽  
pp. 7256
Author(s):  
Daryush D. Mehta ◽  
James B. Kobler ◽  
Steven M. Zeitels ◽  
Matías Zañartu ◽  
Emiro J. Ibarra ◽  
...  
Keyword(s):  
Vocal Fold ◽  
High Speed ◽  
Pressure Sensors ◽  
Pressure Probe ◽  
Surgical Removal ◽  
In Vivo Measurement ◽  
Dual Sensor ◽  
The Right ◽  
Collision Pressure

The purpose of this paper is to report on the first in vivo application of a recently developed transoral, dual-sensor pressure probe that directly measures intraglottal, subglottal, and vocal fold collision pressures during phonation. Synchronous measurement of intraglottal and subglottal pressures was accomplished using two miniature pressure sensors mounted on the end of the probe and inserted transorally in a 78-year-old male who had previously undergone surgical removal of his right vocal fold for treatment of laryngeal cancer. The endoscopist used one hand to position the custom probe against the surgically medialized scar band that replaced the right vocal fold and used the other hand to position a transoral endoscope to record laryngeal high-speed videoendoscopy of the vibrating left vocal fold contacting the pressure probe. Visualization of the larynx during sustained phonation allowed the endoscopist to place the dual-sensor pressure probe such that the proximal sensor was positioned intraglottally and the distal sensor subglottally. The proximal pressure sensor was verified to be in the strike zone of vocal fold collision during phonation when the intraglottal pressure signal exhibited three characteristics: an impulsive peak at the start of the closed phase, a rounded peak during the open phase, and a minimum value around zero immediately preceding the impulsive peak of the subsequent phonatory cycle. Numerical voice production modeling was applied to validate model-based predictions of vocal fold collision pressure using kinematic vocal fold measures. The results successfully demonstrated feasibility of in vivo measurement of vocal fold collision pressure in an individual with a hemilaryngectomy, motivating ongoing data collection that is designed to aid in the development of vocal dose measures that incorporate vocal fold impact collision and stresses.

In vivo measurement of retinal physiology with high-speed ultrahigh-resolution optical coherence tomography

2006 ◽  
Vol 31 (15) ◽  
pp. 2308 ◽  
Author(s):  
V. J. Srinivasan ◽  
M. Wojtkowski ◽  
J. G. Fujimoto ◽  
J. S. Duker
Keyword(s):  
Optical Coherence Tomography ◽  
High Speed ◽  
Optical Coherence ◽  
Ultrahigh Resolution ◽  
In Vivo Measurement

scholarly journals In vivo anterior segment imaging in the rat eye with high speed white light full-field optical coherence tomography

2005 ◽  
Vol 13 (16) ◽  
pp. 6286 ◽  
Author(s):  
Kate Grieve ◽  
Arnaud Dubois ◽  
Manuel Simonutti ◽  
Michel Paques ◽  
José Sahel ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
White Light ◽  
High Speed ◽  
Anterior Segment ◽  
Optical Coherence ◽  
Full Field ◽  
Anterior Segment Imaging

scholarly journals Parallel Fourier domain optical coherence tomography for in vivo measurement of the human eye

2005 ◽  
Vol 13 (4) ◽  
pp. 1131 ◽  
Author(s):  
Branislav Grajciar ◽  
Michael Pircher ◽  
Adolf F. Fercher ◽  
Rainer A. Leitgeb
Keyword(s):  
Optical Coherence Tomography ◽  
Fourier Domain ◽  
Optical Coherence ◽  
Human Eye ◽  
In Vivo Measurement

scholarly journals Ultraflexible, large-area, physiological temperature sensors for multipoint measurements

2015 ◽  
Vol 112 (47) ◽  
pp. 14533-14538 ◽  
Author(s):  
Tomoyuki Yokota ◽  
Yusuke Inoue ◽  
Yuki Terakawa ◽  
Jonathan Reeder ◽  
Martin Kaltenbrunner ◽  
...  
Keyword(s):  
High Speed ◽  
Temperature Stability ◽  
High Sensitivity ◽  
Thermal Sensors ◽  
Large Area ◽  
Active Matrix ◽  
In Vivo Measurement ◽  
Warm Blooded Animal ◽  
Acrylate Polymers

We report a fabrication method for flexible and printable thermal sensors based on composites of semicrystalline acrylate polymers and graphite with a high sensitivity of 20 mK and a high-speed response time of less than 100 ms. These devices exhibit large resistance changes near body temperature under physiological conditions with high repeatability (1,800 times). Device performance is largely unaffected by bending to radii below 700 µm, which allows for conformal application to the surface of living tissue. The sensing temperature can be tuned between 25 °C and 50 °C, which covers all relevant physiological temperatures. Furthermore, we demonstrate flexible active-matrix thermal sensors which can resolve spatial temperature gradients over a large area. With this flexible ultrasensitive temperature sensor we succeeded in the in vivo measurement of cyclic temperatures changes of 0.1 °C in a rat lung during breathing, without interference from constant tissue motion. This result conclusively shows that the lung of a warm-blooded animal maintains surprising temperature stability despite the large difference between core temperature and inhaled air temperature.

scholarly journals Phytochemical, Pharmacological, and Biotechnological Study of Ageratina pichinchensis: A Native Species of Mexico

Plants ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2225
Author(s):  
Mariana Sánchez-Ramos ◽  
Silvia Marquina-Bahena ◽  
Laura Alvarez ◽  
Angélica Román-Guerrero ◽  
Antonio Bernabé-Antonio ◽  
...  
Keyword(s):  
Native Species ◽  
Biological Effects ◽  
Critical Evaluation ◽  
Cell Suspension Cultures ◽  
Future Research ◽  
Research Perspectives ◽  
Crude Extracts ◽  
Pure Compounds

Ageratina pichinchensis (Asteraceae) has been used for a long time in traditional Mexican medicine for treating different skin conditions and injuries. This review aimed to provide an up-to-date view regarding the traditional uses, chemical composition, and pharmacological properties (in vitro, in vivo, and clinical trials) that have been achieved using crude extracts, fractions, or pure compounds. Moreover, for a critical evaluation of the published literature, key databases (Pubmed, Science Direct, and SciFinder, among others) were systematically searched using keywords to retrieve relevant publications on this plant. Studies that reported on crude extracts, fractions, or isolated pure compounds of A. pichinchensis have found a varied range of biological effects, including antibacterial, curative, antiulcer, antifungal, and anti-inflammatory activities. Phytochemical analyses of different parts of A. pichinchensis revealed 47 compounds belonging to chromenes, furans, glycosylated flavonoids, terpenoids, and essential oils. Furthermore, biotechnological studies of A. pichinchensis such as callus and cell suspension cultures have provided information for future research perspectives to improve the production of valuable bioactive compounds.

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