Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Optical Devices”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7Linked to original sources
PubMed2004

In vivo determination of skin surface topography using an optical 3D device.

BACKGROUND/PURPOSE: Topography of the skin surface is a mirror of the functional skin status. Therefore, its evaluation is of great interest for dermatological research. In the present study, a new optical measuring system was applied to evaluate human skin surface topography in vivo and non-invasively, in order to determine elastotic and mimic wrinkles dependent on age, body site and therapy. METHODS: The measurements were performed on the back (n=5), the flexor forearm (n=14) of volunteers in different age groups and on the face of women (n=4) participating in an anti-wrinkle study. The evaluation of the three-dimensional-profiles was performed determining skin surface parameters (mean roughness (R(a)), mean depth of roughness (R(z)), maximum roughness (R(m)) and waviness (W(t))) and applying Fourier analysis. RESULTS: Significant increases in all surface parameters were obtained on the forearms with increasing age. Differences between the surface topographies of forearm and back were only expressed by the waviness and the Fourier analysis. The treatment with botulinum Toxin A led to a diminution of mimic wrinkles as reflected by the furrow profiles. CONCLUSIONS: The results show a significant dependence of the skin surface topography on the age of the volunteer and the body site measured. Particularly the waviness, the Fourier analysis and the furrow profiles reflect such dependencies. The system used also fulfils the requirements for the testing of therapies, as was demonstrated by the reduction of mimic wrinkles after treatment with botulinum Toxin A.

Adult↗
PubMed2004

Comparison of invasive and noninvasive measurement of plasma disappearance rate of indocyanine green in patients undergoing liver transplantation: a prospective investigator-blinded study.

Plasma disappearance rate of indocyanine green (PDRICG) has been proposed for assessment of liver function in liver transplants donors and recipients, in patients with chronic liver failure, and as a prognostic factor in critically ill patients. The assessment of PDRICG using a newly developed noninvasive digital pulse densitometry method was simultaneously compared to invasive aortic fiber-optic method in patients undergoing orthotopic liver transplantation (OLT). Fourteen consecutive liver transplant candidates (11 male, 3 female) were prospectively enrolled into the study. A 4F aortic catheter with an integrated fiber-optic device and a thermistor was inserted via a femoral artery sheath for invasive aortic (INV) PDRICG assessment in all patients. The fiber-optic device was connected to a computer system (COLD-Z021, PULSION Medical Systems, Munich, Germany). A finger-piece sensor was used for non-invasive (NINV) pulse-densitometric PDRICG assessment. For the PDRICG assessment.5 mg/kg of ICG in cooled saline (10-15 mL) was injected through a central venous catheter. The assessments of PDRICG were performed after induction of anesthesia, after clamping of the hepatic artery, after clamping of the inferior vena cava, after reperfusion of the graft, and on the first postoperative day. During the PDRICG measurements, the investigators were blinded for the results of the noninvasive monitoring. Seventy-one pairs of measurements were performed successfully. PDRICG ranged from 0%/min to 43.8 %/min (11.6%/min +/- 9.6 %/min, mean +/- SD) for invasive and from 2.6%/min to 36.1 %/min (10%/min +/- 7.6 %/min, mean +/- SD) for noninvasive assessment method. The linear regression analysis yielded the equation: PDRICG(NINV) = 1.493 +/- 0.735 x PDRICG(INV), with a correlation coefficient of r = 0.93 (P <.0001). The analysis according to Bland and Altman showed a good agreement between the PDRICG(NINV) and PDRICG(INV) with a mean bias 1.5 +/- 3.8 for all measurements. In conclusion, according to these results, the noninvasive transcutaneous pulse-densitometric method correlates well with the invasive aortic fiber-optic method and thus can be used in patients undergoing liver transplantation.

Coloring Agents↗
PubMed2001

Ocular fundus images with confocal scanning laser ophthalmoscopy in the dog, monkey and minipig.

Confocal scanning laser ophthalmoscopy (CSLO) is a new technique that enables ocular fundus image recording and retinal dynamic angiography to be performed. The ocular fundus image is acquired sequentially, point by point, and is reconstructed on a video monitor at the rate of 25 images per second. The feasibility of performing both ocular fundus image recordings and retinal angiography image recordings were tested on two dogs, two monkeys and two minipigs using a 40 degrees field I + Tech CSLO. Fundus area of each dog, monkey and minipig were examined without any additional optical devices. The ocular fundus and angiography images were recorded, stabilized and analyzed under the same conditions. For each species, all images were easily recorded without any additional optical device in a lighted room and the morphology of the retinal images generated was similar to those obtained with a camera or angiography of higher resolution. Capillary phase or venous times are presented. Image recording at 25 frames/second enabled more retinal dynamics to be demonstrated than with use of regular angiography. This technique is noninvasive and easy to perform if the eye is fixed and eyelids maintained open. It also allows exploration of retinal microvascularization and could be utilized for clinical, pharmacologic and toxicologic investigations as well.

Animals↗
PubMed1993

[Asymmetric multizone lenses--a new concept in multifocal intraocular lenses].

BACKGROUND: Asymmetrical multifocal lenses (MIOLs) represent a new concept for binocular implantation of MIOLs: one asymmetrical IOL--destined for implantation in the dominant eye--is favouring distance vision by assuring that 60-70% of the light rays coming from an object will pass through the distance part of the optic. The other IOL--destined for implantation in the second eye--is favouring near vision, enabling that 60-70% of the light energy will be focused by the near zone(s) of the IOL. METHODS: Modulation transfer function (MTF), Strehl-Ratio (SR) and resolution efficiency (RE) were determined in both foci by in vitro measurement. Defocus curves were performed after clinical implantation as well as after "optical implantation" by means of an optical device developed by Reiner. RESULTS: In vitro measurements showed superior results of SR and RE in the favoured focus of the MIOL. Defocus curves after clinical and "optical" implantation yielded higher peaks for visual acuity and contrast in the favoured focus. CONCLUSION: First theoretical and clinical results do confirm the new concept of asymmetrical multifocal IOLs.

Contrast Sensitivity↗
PubMed2006

Recognition of organic solvents molecules by simultaneous detection using SAW oscillator sensors and optical fiber devices coated by Langmuir-Blodgett cadmium arachidate films.

Surface acoustic waves (SAW) 433 and 315 MHz, two-port resonator-based oscillators coated with a Langmuir-Blodgett (LB) thin layer of chemosensitive cadmium arachidate (CdA) provide highly sensitive chemical acoustic sensors for detection and monitoring of organic vapors, at room temperature. LB CdA film-coated silica optical fibers (SOF) have been successfully fabricated and studied for organic solvents molecules sensing applications. The sensing performance of both types of acoustic and optical transducers has been compared for detecting six molecular species. Simultaneous measurements of frequency changes (delta f) and optoelectronic signal changes (deltaV) of the LB CdA film assembled onto SAW sensors and SOF devices have been realized for organic vapors recognition purposes. Six molecular species such as ethanol, methanol, isopropanol, ethylacetate, acetone, and toluene have been identified and recognized by a specific index (deltaf/deltaV), which can be considered a characteristic property of the chemosensitive material. The discrimination of the six molecular species examined also has been obtained by chemical patterns using a couple of specific index (deltaf433/deltaV; deltaf315/deltaV) measured by combining SAW 433 or 315 MHz oscillators and SOF sensing devices. Transient responses, calibration curves, intertransducer relationships, and chemical patterns are presented and discussed.

Journal Article↗
PubMed2005

Electro-tunable optical diode based on photonic bandgap liquid-crystal heterojunctions.

Manipulation of light is in strong demand in information technologies. Among the wide range of linear and nonlinear optical devices that have been used, growing attention has been paid to photonic crystals that possess a periodic modulation of dielectric function. Among many photonic bandgap (PBG) structures, liquid crystals with periodic structures are very attractive as self-assembled photonic crystals, leading to optical devices such as dye lasers. Here we report a new hetero-PBG structure consisting of an anisotropic nematic layer sandwiched between two cholesteric liquid-crystal layers with different helical pitches. We optically visualized the dispersion relation of this structure, displaying the optical diode performance: that is, the non-reciprocal transmission of circular polarized light at the photonic-bandgap regions. Transmittance spectra with circularly polarized light also reveal the diode performance, which is well simulated in calculations that include an electro-tunable diode effect. Lasing action was also confirmed to show the diode effect with a particular directionality.

Journal Article↗
PubMed2006

Reading aids for adults with low vision.

BACKGROUND: The purpose of low vision rehabilitation is to allow people to resume or to continue to perform daily living tasks, reading being one of the most important. This is achieved by providing appropriate optical devices and special training in the use of residual vision and low vision aids, which range from simple optical magnifiers to high power video magnifiers. OBJECTIVES: The objective of this review was to assess the effects of reading aids for adults with low vision. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Group Trials Register) in The Cochrane Library, MEDLINE, EMBASE, SIGLE, LILACS, IndMed to July 2006 and the reference lists of relevant articles. We used the Science Citation Index to find articles that cited the included studies and contacted investigators and manufacturers of low vision aids. We handsearched the British Journal of Visual Impairment from 1983 to 1999 and the Journal of Visual Impairment and Blindness from 1976 to 1991. SELECTION CRITERIA: This review included randomised and quasi-randomised trials in which any device or aid used for reading had been compared to another device or aid in people aged 16 or over with low vision as defined by the study investigators. DATA COLLECTION AND ANALYSIS: Each author independently assessed trial quality and extracted data. MAIN RESULTS: Eight small studies with a cross-over design (221 people overall) and one three parallel-arm study (243 participants) were included in the review. The cross-over studies evaluated various types of aids. The quality of the studies was unclear in most cases, especially concerning carry-over or period effects. In one study on 20 participants head-mounted electronic devices (four types) were worse than optical devices. We could not find any differences in comparisons among electronic devices when pooling 23 participants of two small studies. One study on 10 people found that overlay coloured filters were no better than a clear filter. A parallel-arm study including 243 patients with age-related macular degeneration found that custom or standard prism spectacles are not different from conventional near spectacles, but the estimated difference was not precise. AUTHORS' CONCLUSIONS: Further research is needed on the comparison of different types of low vision aids. It will be also necessary to delineate patient's characteristics that predict performance with costly electronic devices as well as their sustained use in the long term compared to simpler and cheaper optical devices.

Adult↗
PubMed1993

A simple optical fiber device for quantitative fluorescence microscopy of single living cells.

A simple and relatively inexpensive system is described for obtaining quantitative fluorescence measurements on single living cells loaded with a fluorescent probe to study cell physiological processes. The light emitted from the fluorescent cells is captured by and transported through an optical fiber. After passage through appropriate filters the light is measured using a photomultiplier tube. The optical fiber is mounted in one of the microscope outlets. Signals derived from the photomultiplier are converted to voltage, amplified, and displayed on a recorder. In the excitation pathway a shutter control unit is mounted. With this control unit the period that the excitation pathway is 'opened' and 'closed' can be adjusted, to reduce cell damage and/or bleaching of the probe. This option allows time-lapse recording of experiments up to 1 h. We have used this set-up with a single and dual emission fluorescent probe to determine intracellular calcium concentrations and pH, respectively. In Fluo-3-loaded K562 target cells bound to natural killer cells, a temporary rise in [Ca2+]i was accompanied by bleb formation. The simple construction of this set-up is interchangeable between different types of fluorescence microscopes and can easily be combined with other microscopy techniques, e.g., patch clamp.

Calcium↗
PubMed1990

Fiber optic evanescent wave immunosensors for medical diagnostics.

Immunodiagnostic sensors permit sensitive measurement of a wide variety of both high and low molecular mass analytes--serum analytes may be detected at picomolar concentrations. Due to the sensor monitoring antigen--antibody reactions directly, quantitative results are available within seconds to minutes of sample introduction. In recent years, the trend has been for immunodiagnostics to be used at sites away from centralized medical laboratories. Specific requirements associated with such use are being achieved by the development of optical devices incorporating evanescent wave sensors.

Animals↗
PubMed2006

Integrated optoelectronic probe including a vertical cavity surface emitting laser for laser Doppler perfusion monitoring.

An integrated optoelectronic probe with small dimensions, for direct-contact laser Doppler blood flow monitoring has been realized. A vertical cavity surface emitting laser (VCSEL), and a chip with photodetectors and all necessary electronics are integrated in a miniature probe head connected to a laptop computer. The computer sound processor is utilized for acquisition and digital signal processing of the incoming Doppler signal. In this paper, the design of the laser Doppler perfusion monitor is described and its performance is evaluated. We demonstrate our perfusion monitor to be less sensitive to subject motion than a commercial fiber-optic device. For medium and high perfusion levels, the performance of our integrated probe is comparable to the fiberoptic flowmeter containing a normal edge-emitting laser diode. For very low perfusion levels, the signal-to-noise ratio of the fiber-optic device is higher. This difference can mainly be attributed to the shorter coherence length of the VCSEL compared with the edge-emitting laser diode.

Diagnosis, Computer-Assisted↗
PubMed2005

The effect of rehabilitation on depression among visually disabled older adults.

There has been a great deal of interest in identifying the impact of rehabilitation on psychological well-being, as well as functional ability, among elders with disabilities, but empirical data remain limited. This descriptive study of participants in vision rehabilitation service examines the effect of specific vision rehabilitation services (low vision clinical services, skills training, counseling, optical device use, and adaptive device use) on change in depression among a sample of older adults with age-related vision impairments. Participants (N = 95) were interviewed at application for services and then approximately two years later. Findings from hierarchical regression analyses indicated that low vision clinical services, counseling, and use of optical devices, in separate models, each significantly contributed to a decline in depression, after controlling for age, health status, vision status, functional disability, as well as baseline depression. When all service variables were entered into the same equation, they explained an additional 10% of the variance in change in depression. Given the well documented robust relationship between disability and depression, findings point to the influence of vision rehabilitation interventions on both physical and psychological functioning, and underscore the need for future, controlled research on rehabilitation service models that address mental health issues.

Adaptation, Psychological↗
PubMed1997

An intraocular telescopic lens for macular degeneration.

Age-related macular degeneration is a leading cause of visual loss in adults older than 60 years of age. Once vision has been seriously compromised, the only means of improving visual function are optical devices that produce magnification of images. These devices fall into three categories: (1) high-plus lenses, (2) external telescopes, and (3) a high-minus center intraocular lens combined with external high-plus glasses. The authors designed a new intraocular lens with an entire telescope in its center. In vitro tests were performed to evaluate modulation transfer function, visual field, and optical aberrations. Implantation in cadaver eyes was performed to test the surgical technique and safety. Test results showed that satisfactory modulation transfer function and optic aberration were achieved, and implantation in cadaver eyes was proven to be feasible and safe. It was concluded that a fully implanted intraocular telescopic lens is an effective optical solution for age-related macular degeneration.

Adult↗
PubMed1993

[Modulation transfer function and contrast sensitivity of refractive multi-zone multi-focal lenses].

Contrast imaging of new multifocal intraocular lens (MIOL) designs with 5 and 7 refractive zones was examined by in vitro measurement of the modulation transfer function (MTF) and by testing contrast sensitivity with Regan 96% and 11% contrast sensitivity charts after "optical implantation" of MIOLs in 20 healthy subjects by means of a new optical device developed by Reiner. The results were compared with those obtained with a monofocal IOL and a diffractive MIOL. We found that the MTF of both refractive MIOLs showed a reduction in contrast at corresponding spatial frequencies compared with the monofocal and with the diffractive IOL, resulting in a Strehl ratio of below 30%. Contrast sensitivity after "optical implantation" was significantly reduced for the refractive 5- and 7-zone models in high contrast (Regan 96%), but for all MIOL models in low contrast (Regan 11%) compared with the monofocal IOL. The refractive 5-zone MIOL and diffractive MIOL showed no statistical difference in contrast sensitivity.

Contrast Sensitivity↗
PubMed1999

Newly developing endoscopic devices--shadow optics and micromachine.

Based on the newly-developed engineering technologies, many kinds of useful equipment have been available for minimally invasive surgery. Recently the time to connect clinical needs and advanced technologies has become faster. In this article, we have summarized the recent technologies for endoscopic surgeries. Shadow optic technologies for better geometric perception using dual illumination in a conventional 2-D monitor and "Overview optics" for a panoramic view with an additional visual system are introduced. Micromachine technology is very close to practical implementation for minimally invasive surgeries. Virtual Biopsy is the one of the hottest topics for the next generation of endoscopy. Stereoscopic and volumetric vision systems are still on the way, which should overcome the irritating goggles and stereo display devices. As well as operational theater that integrates all the required equipment with a computer-based system, including voice recognition, still requires the standard protocols to connect many kinds of devices from different manufacturers.

Biopsy↗
PubMed1983

Recent advances in clinical low-vision care.

In the past decade there has been a growth in the awareness of the impact that low vision has on the individual and on society in general. The clinical eye-care professions have become more conscious of their responsibility to assist partially sighted patients and low-vision care is becoming a specialty area within optometry and ophthalmology. This paper reviews recent advances in the optical devices and prescribing procedures that have contributed to improving the care that is available to assist low-vision patients with distance-vision tasks, near-vision tasks and visual-field problems.

Distance Perception↗
PubMed1996

Analysis of edge-losses in reflectance measurements of pigmented maxillofacial elastomer.

Edge-losses occur during reflectance measurements of pigmented maxillofacial elastomer when light is scattered within a sample beyond that part of the surface exposed to the observation system of the optical device. A custom sample-holder is presented which redirects light that would not be measured during conventional reflectance measurement back into the sample. The amount of edge-loss occurring within thin layers of maxillofacial elastomer with tan pigment on black-and-white backings was found to depend on sample thickness, the backing, the beam size used during conventional reflectance measurement, and the optical term bS = (2KS + K2)1/2. Data analysis revealed a significant interaction among these four factors. Additionally, the edge-loss occurring during the tristimulus reflectance measurement of thick samples of maxillofacial elastomer with various concentrations of tan and black pigment was found to be linearly related to bS up to a limiting value, with no additional edge-loss occurring for bS values above this limiting value. Edge-loss is an important consideration during the matching of the optical characteristics of pigmented maxillofacial material to those of human skin.

Absorption↗
PubMed2001

Self-monitoring of water quality in sewer systems using absorbance of ultraviolet and visible light.

Continuous pollution measurement is interesting to optimize the operation of sanitary facilities as well as to minimize the stormwater discharges. An experimental study was carried out for the determination of Suspended Solids (SS) and Chemical Oxygen Demand (COD) concentrations in combined sewers using ultraviolet and visible absorbances. The maintenance of the measurement system requires six hours a month for the cleaning of the hydraulic feeding system and adjustment of the optical device. The feeding system developed increased the representativeness and reliability of the pollution measurement, but needs to be validated on other measurement sites. The determination of SS concentrations from visible absorbances requires 2 calibration curves for dry and rainy weather respectively. The corresponding accuracies appear satisfactory when compared with the results of standard sampling/laboratory analysis. The accuracy of COD determination from ultraviolet absorbance is less satisfactory, but could perhaps be improved taking into account another parameter. Then the optical measurement of SS and COD is interesting to determine average or long term pollution loads, for example the yearly impact of urban stormwater discharges. With this kind of continuous and on-line measurement, it is possible to react with short delay to unexpected phenomena which could damage the environment or water treatment efficiency.

Absorption↗