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in subjects: "Retina"

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Solar energy research at Sandia Laboratories and its effects on health and safety

Various solar energy research and development projects at Sandia Laboratories are discussed with emphasis on the primary health and safety hazard associated with solar concentration systems. This limiting hazard is chorioretinal damage. The unique safety and health hazards associated with solar energy collector and receiver systems cannot be measured yet, but progress is being made rapidly. Research is continuing, especially for eye hazards, with more extensive work planned.

Date: October 1, 1977

Creator: Young, L. L., III

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Characterization of an AO-OCT system

Adaptive optics (AO) and optical coherence tomography (OCT) are powerful imaging modalities that, when combined, can provide high-volumetric-resolution, images of the retina. The AO-OCT system at UC Davis has been under development for 2 years and has demonstrated the utility of this technology for microscopic, volumetric, in vivo retinal imaging [1]. The current system uses an AOptix bimorph deformable mirror (DM) for low-order, high-stroke correction [2] and a 140-actuator Boston Micromachine… more

Date: July 26, 2007

Creator: Evans, J. W.; Zawadzki, R. J.; Jones, S.; Olivier, S. & Werner, J. S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Luminance controlled pupil size affects Landolt C task performance

Subjects judged the orientation of a 2 min. gap Landolt C located at a distance of 2.4 m. The stimuli were presented in central vision on a CRT, at low to medium contrast. The effects of varying the spectrum and luminance of surround lighting were assessed on both pupil size (measured using infrared pupillometry during task performance) and task accuracy. The task display was protected from the surround lighting, so that its luminance and contrast could be varied independently of the changes in… more

Date: February 1, 1993

Creator: Berman, S.M. (Lawrence Berkeley Lab., CA (United States)); Fein, G. (Neurobehavioral Lab. Software, San Rafael, CA (United States)); Jewett, D.L. & Ashford, F. (ABRATech Corp., Mill Valley, CA (United States))

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Mechanism of activation of light-activated phosphodiesterase and evidence for homology with hormone-activated adenylate cyclase

Light-activated cGMP phosphodiesterase (PDE) is one of the effector proteins in the rod outer segments in vertebrate retina. The hydrolysis of cGMP in rod occurs with a speed and light sensitivity which suggests a role for this hydrolysis in visual transduction. In fact, there is electrophysiological data which supports the possibility that cGMP could regulate rod membrane voltage. PDE shows very rapid activation in the presence of photons and GTP. We have called attention to the intriguing ana… more

Date: January 1, 1983

Creator: Bitensky, M. W.; Yamazaki, A.; Wheeler, M. A.; George, J. S. & Rasenick, M. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Cellular proliferation and regeneration following tissue damage. Progress report

Tissue cultures of rabbit retinal vasculature were studied in vivo and in vitro by scanning electron microscopy to elucidate the regnerative process from an injury. Human lens are now being compared with a goal for developing a bioassay for testing the effects of potentially toxic agents. (PCS)

Date: January 1, 1978

Creator: Harding, C.V.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Effects of ionizing radiation on the light sensing elements of the retina. [Structural and physiological effects of carbon, helium, and neon ions on rods and cones of salamanders and mice]

This investigation was undertaken to quantitate possible morphological and physiological effects of particles of high linear energy transfer on the retina, in comparison with x-ray effects. The particles used were accelerated atomic nuclei of helium, carbon, and neon at kinetic energies of several hundred MeV/nucleon. For morphological studies, scanning and transmission electron microscopy and light microscopy were used. Physiological studies consisted of autoradiographic data of the rate of in… more

Date: July 1, 1978

Creator: Malachowski, M.J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Microfabrication of an Implantable silicone Microelectrode array for an epiretinal prosthesis

Millions of people suffering from diseases such as retinitis pigmentosa and macular degeneration are legally blind due to the loss of photoreceptor function. Fortunately a large percentage of the neural cells connected to the photoreceptors remain viable, and electrical stimulation of these cells has been shown to result in visual perception. These findings have generated worldwide efforts to develop a retinal prosthesis device, with the hope of restoring vision. Advances in microfabrication, i… more

Date: June 10, 2003

Creator: Maghribi, M

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

open access

Luminance controlled pupil size affects Landolt C task performance. Revision

Date: February 1, 1993

Creator: Berman, S. M.; Fein, G.; Jewett, D. L. & Ashford, F.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Quality Assessment of Retinal Fundus Images using Elliptical Local Vessel Density

Diabetic retinopathy is the leading cause of blindness in the Western world. The World Health Organisation estimates that 135 million people have diabetes mellitus worldwide and that the number of people with diabetes will increase to 300 million by the year 2025 (Amos et al., 1997). Timely detection and treatment for DR prevents severe visual loss in more than 50% of the patients (ETDRS, 1991). Through computer simulations is possible to demonstrate that prevention and treatment are relatively… more

Date: January 1, 2010

Creator: Giancardo, Luca; Meriaudeau, Fabrice; Karnowski, Thomas Paul; Chaum, Edward & Tobin Jr, Kenneth William

Item Type: Book

Partner: UNT Libraries Government Documents Department

open access

IFESS 2005 Special Session 5 Artifical Vision

A special session on visual prostheses was held during the Annual Meeting of the International Functional Electrical Stimulation Society (IFESS), in Montreal, Canada, July 5-9, 2005. IFESS is a meeting that typically attracts researchers in implantable nerve stimulators, functional electrical stimulation, and rehabilitation. All of these areas have significant overlap with the retinal prosthesis, but these areas have decades of research behind them. The special session provided a forum for rese… more

Date: July 1, 2005

Creator: Weiland, J. D.; Greenbaum, E.; Delbeke, J.; Troyk, P. R. & Sawan, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Adaptive optics ophthalmologic systems using dual deformable mirrors

Adaptive Optics (AO) have been increasingly combined with a variety of ophthalmic instruments over the last decade to provide cellular-level, in-vivo images of the eye. The use of MEMS deformable mirrors in these instruments has recently been demonstrated to reduce system size and cost while improving performance. However, currently available MEMS mirrors lack the required range of motion for correcting large ocular aberrations, such as defocus and astigmatism. In order to address this problem,… more

Date: February 1, 2007

Creator: Jones, S.; Olivier, S.; Chen, D.; Sadda, S.; Joeres, S.; Zawadzki, R. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

High-resolution adaptive optics scanning laser ophthalmoscope with dual deformable mirrors for large aberration correction

Scanning laser ophthalmoscopes with adaptive optics (AOSLO) have been shown previously to provide a noninvasive, cellular-scale view of the living human retina. However, the clinical utility of these systems has been limited by the available deformable mirror technology. In this paper, we demonstrate that the use of dual deformable mirrors can effectively compensate large aberrations in the human retina, making the AOSLO system a viable, non-invasive, high-resolution imaging tool for clinical d… more

Date: January 25, 2007

Creator: Chen, D.; Jones, S. M.; Silva, D. A. & Olivier, S. S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Modeling and Simulation of Microelectrode-Retina Interactions

The goal of the retinal prosthesis project is the development of an implantable microelectrode array that can be used to supply visually-driven electrical input to cells in the retina, bypassing nonfunctional rod and cone cells, thereby restoring vision to blind individuals. This goal will be achieved through the study of the fundamentals of electrical engineering, vision research, and biomedical engineering with the aim of acquiring the knowledge needed to engineer a high-density microelectrod… more

Date: November 30, 2002

Creator: Beckerman, M

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Is Lutein a Physiologically Important Ligand for Transthyretin in Humans?

Lutein and zeaxanthin are the only carotenoids accumulated in the macula of the human retina and are known as the macular pigments (MP). These pigments account for the yellow color of the macula and appear to play an important role in protecting against age-related macular degeneration (AMD). The uptake of lutein and zeaxanthin in human eyes is remarkably specific. It is likely that specific transport or binding proteins are involved. The objective is to determine whether transthyretin (TTR) is… more

Date: May 31, 2003

Creator: Chen, Liwei

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

open access

Comparative nuclear effects of biomedical interest. Civil effects study

Selected physical and biological data bearing upon the environmental variations created by nuclear explosions are presented in simplified form. Emphasis is placed upon the ``early`` consequences of exposure to blast, thermal radiation, and ionizing radiation to elucidate the comparative ranges of the major effects as they vary with explosive yield and as they contribute to the total hazard to man. A section containing brief definitions of the terminology employed is followed by a section that u… more

Date: January 12, 1961

Creator: White, C.S.; Bowen, I.G.; Richmond, D.R. & Corsbie, R.L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Nonlinear spatio-temporal interactions and neural connections in human vision using transient and M-sequence stimuli

Reciprocal connections, in essence, are the dynamic wiring (connections) of the neural network circuitry. Given the high complexity of the neural circuitry in the human brain, it is quite a challenge to study the dynamic wiring of highly parallel and widely distributed neural networks. The measurements of stimulus evoked coherent oscillations provide indirect evidence of dynamic wiring. In this study, in addition to the coherent oscillation measurements, two more techniques are discussed for te… more

Date: February 1, 1996

Creator: Chen, H. W.; Aine, C. J.; Flynn, E. R. & Wood, C. C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Stretchable Micro-Electrode Array

This paper focuses on the design consideration, fabrication processes and preliminary testing of the stretchable micro-electrode array. We are developing an implantable, stretchable micro-electrode array using polymer-based microfabrication techniques. The device will serve as the interface between an electronic imaging system and the human eye, directly stimulating retinal neurons via thin film conducting traces and electroplated electrodes. The metal features are embedded within a thin ({appr… more

Date: March 8, 2002

Creator: Maghribi, M.; Hamilton, J.; Polla, D.; Rose, K.; Wilson, T. & Krulevitch, P.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Characterizing the Material Properties of Polymer-Based Microelectrode Arrays for Retinal Prosthesis

The Retinal Prosthesis project is a three year project conducted in part at the Lawrence Livermore National Laboratory and funded by the Department of Energy to create an epiretinal microelectrode array for stimulating retinal cells. The implant must be flexible to conform to the retina, robust to sustain handling during fabrication and implantation, and biocompatible to withstand physiological conditions within the eye. Using poly(dimethyl siloxane) (PDMS), LLNL aims to use microfabrication te… more

Date: May 10, 2003

Creator: Park, C S & Maghribi, M

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

open access

Characterization and Operation of Liquid Crystal Adaptive Optics Phoropter

Adaptive optics (AO), a mature technology developed for astronomy to compensate for the effects of atmospheric turbulence, can also be used to correct the aberrations of the eye. The classic phoropter is used by ophthalmologists and optometrists to estimate and correct the lower-order aberrations of the eye, defocus and astigmatism, in order to derive a vision correction prescription for their patients. An adaptive optics phoropter measures and corrects the aberrations in the human eye using ad… more

Date: February 5, 2003

Creator: Awwal, A.; Bauman, B.; Gavel, D.; Olivier, S.; Jones, S.; Hardy, J. L. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Observations by Human Subjects on Radiation-Induced Light Flashes in Fast- Neutron, X-Ray, and Positive-Pion Beams.

No Description Available.

Date: January 1, 1970

Creator: Tobias, C. A.; Budinger, T. F. & Lyman, J. T.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

In vivo cellular visualization of the human retina using optical coherence tomography and adaptive optics

Optical coherence tomography (OCT) sees the human retina sharply with adaptive optics. In vivo cellular visualization of the human retina at micrometer-scale resolution is possible by enhancing Fourier-domain optical-coherence tomography with adaptive optics, which compensate for the eye's optical aberrations.

Date: January 5, 2006

Creator: Olivier, S. S.; Jones, S. M.; Chen, D. C.; Zawadzki, R. J.; Choi, S. S.; Laut, S. P. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

High-Resolution Adaptive Optics Scanning Laser Ophthalmoscope with Dual Deformable Mirrors

Adaptive optics scanning laser ophthalmoscope (AO SLO) has demonstrated superior optical quality of non-invasive view of the living retina, but with limited capability of aberration compensation. In this paper, we demonstrate that the use of dual deformable mirrors can effectively compensate large aberrations in the human retina. We used a bimorph mirror to correct large-stroke, low-order aberrations and a MEMS mirror to correct low-stroke, high-order aberration. The measured ocular RMS wavefro… more

Date: August 11, 2006

Creator: Chen, D. C.; Jones, S. M.; Silva, D. A. & Olivier, S. S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Photo-initiated processes in version. Final report

Progress is reported on an investigation of early events in visual excitation using electron spin resonance signals from retinal materials such as rhodopsin and whole retinas. Electron transfer process in response to light and radical participation in the initial event of vision were investigated. The possibility of using fluorescences as an indicator of structural changes in visual pigments and vitamin A aldehyde radical was studied using intact frog retinas.

Date: March 31, 1978

Creator: Guzzo, A.V.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Computational modeling of stress transient and bubble evolution in short-pulse laser irradiated melanosome particles

Objective is to study retinal injury by subnanosecond laser pulses absorbed in the retinal pigment epithelium (RPE) cells. The absorption centers in the RPE cell are melanosomes of order 1 {mu}m radius. Each melanosome includes many melanin particles of 10-15 nm radius, which are the local absorbers of the laser light and generate a discrete structure of hot spots. This work use the hydrodynamic code LATIS (LAser-TISsue interaction modeling) and a water equation of state to first simulate the s… more

Date: March 4, 1997

Creator: Strauss, M.; Amendt, P. A.; London, R. A.; Maitland, D. J.; Glinsky, M. E.; Lin, C. P. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department