bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies of Vortex-Induced Flame Extinction in Couterflow Diffusion Flames Using CH PLIF and PIV
Authors: Lemaire A. , Meyer T. R. , Zahringer K. , Gord J. R. , Rolon J. C.
Published: February 2023

The interaction between a laminar non premixed flame and a vortex is examined. The CH radical layer produced by the flame is imaged, for the first time in this configuration, using planar laser induced fluorescence (PLIF). Simultaneous partcle-imange velocimetry (PIV) measurements gives flowfield data. The methane-air flame is supported in a nonpremixed opposed-jet burner. In this work, the extinction processes occurred during the interaction is analyzed. Also, in the experiments, it appear that PAH fluorescence strongly perturb CH LIF measurements. To clarify this, the effects of equivalence ratio, droplet seeding and laser energies on CH vs. PAH fluorescence are studied.
Vertical Elliptical Coronas
Authors: Parviainen Pekka , Mäkelä Veikko , Pekkola Marko , Bohren Craig F.
Published: February 2023

Uniform, thin layers of monodisperse water droplets can give rise to coronas: colored rings centered on the sun or moon [1].
Resonance Ionization Mass Spectrometry Using Ion-Beam Sampling
Authors: Goeringer D.E. , Christie W.H.
Published: February 2023

Sputter atomization/resonance ionization mass spectrometry (SA/RIMS) is a highly sensitive technique for materials analysis which combines ion beam sputtering, resonance ionization, and mass spectrometry. A pulsed beam of high-energy primary ions bombards the sample producing a plume of neutral atoms. The cloud of sputtered neutrals is intersected and ionized by a synchronized, pulsed laser beam tuned to a resonant transition for specific sample atoms. Laser-generated ions are then extracted into a mass spectrometer for mass analysis. Ion beam sputtering allows the sampling process to be highly controlled by varying the energy, current density, and composition of the primary beam; the pulsed nature of the beam results in efficient sample utilization. Use of a micro-focused beam permits imaging of small areas and particles. The pulsed dye laser generates the high optical power necessary to efficiently ionize the sputtered atoms. Mass analysis of the laser-generated ions provides the capability for isotope ratio measurements.
Two and Three Dimensional Imaging of Thin Films Using the Raman Microprobe
Authors: Fauchet Philippe M.
Published: February 2023

There is an increasing need for non-destructive characterization techniques that require no special sample preparation, can be used in-situ, and provide quantitative information with good spatial resolution. The Raman microprobe fulfills these requirements. We illustrate the capabilities of the Raman microprobe by presenting results obtained on thin films after laser-induced damage, after laser or rapid thermal annealing, and on heteroepitaxial semiconductor layers. The prospects for two and three-dimensional imaging of important properties such as composition, strain, and crystalline quality or orientation are discussed.
High Frequency Optical Heterodyne Spectroscopy with Lead-Salt Semiconductor Diode Lasers
Authors: Cooper David E.
Published: February 2023

Absorption spectroscopy with lasers has traditionally been limited in sensitivity by noise intrinsic to the laser source. Numerous methods of surmounting this limitation using various forms of sample and source modulation have been proposed and demonstrated. One technique in particular, familiar to most users of lead-salt diode lasers, incorporates low-frequency wavelength modulation of the laser source and detection at either the first or second harmonics of the modulating waveform. Although this technique has been used successfully to measure weak absorptions, it remains fundamentally limited by diode laser amplitude fluctuations because the signal is detected in a frequency regime where the lasers exhibit considerable excess noise. Although the high frequency noise characteristics of lead-salt diode lasers are complex,1,2 one expects their excess noise power to drop considerably at frequencies larger than the intrinsic laser linewidth. Hence, diode laser frequency modulation at radio-frequencies should offer greater immunity to laser noise and consequently a higher sensitivity to absorption than can be obtained with conventional low frequency techniques.
Detection of Methane Leaks with a Correlation Lidar
Authors: Galletti E.
Published: February 2023

An IR light source based on a Lithium Niobate Optical Parametric Oscillator (OPO) has been developed to measure small average concentrations of atmospheric pollutants by LIDAR technique.
Turbulence Measurements in the Convective Boundary Layer with a Short-Pulse CO2 Doppler Lidar
Authors: Eberhard Wynn L. , Hardesty R. Michael , Gal-Chen Tzvi
Published: February 2023

A pulsed, coherent CO2 Doppler lidar (Hardesty et al., 1983, 1987) will attempt a conical scan technique to measure turbulence and momentum fluxes in the convective boundary layer. Kropfli (1986) has shown success with this method using a Doppler radar in the convective boundary layer, but the lidar has an advantage in relying on the ubiquitous aerosol particles as tracers of air motion in a variety of meteorological conditions. We describe the data acquisition and processing methodology, progress in optimizing the lidar's spatial resolution, and the planned field measurement program.
Cloud Liquid Water Derived from Lidar Observations
Authors: Spinhirne James D , Hart William D. , Boers Reinout
Published: February 2023

The distribution of liquid water at the top of clouds has an important relation to the radiative and dynamical interactions within clouds. As a significant example, the formation and structure of marine stratus clouds are maintained primarily by radiative cooling at the cloud top. Understanding the formation of marine stratus is important climatalogically since the cloud type has a significant global influence on the balance between reflected visible and emitted thermal radiation. Models have shown that the interaction between radiative cooling and the cloud development are largley a function of the distribution of the liquid water at the cloud top. Although liquid water may be obtained from in situ measurements, only one dimensional observations are possible. Lidar liquid water observatios can provide a more complete two dimentional representation of the liquid water structure of cloud tops. In this contribution we will describe the lidar retrieval of cloud top liquid water during an experiment in which marine stratus clouds were studied by combined remote sensing and in situ observations.
Advances in Gas-Analyzers Based on IR Molecular lasers
Authors: Andreev Yu. M. , Geiko P.P. , Zuev V.V. , Zuev V.E. , Romanovskii O.A. , Shubin S.F.
Published: February 2023

High operation and power characteristics of CO2 lasers stipulate their wide application in absorption gas-analyzers and lidars [1]. On the other hand, the gas-analyzer possibilities are limited by their narrow spectral emission range. The molecular CO, NH3, HF, HBr lasers generating in different IR regions do not compensate for this disadvantage by different reasons.
Two Scintillation Methods of Measuring the Inner Scale
Authors: Hill Reginald J.
Published: February 2023

Let σ2 (L, k, Cn2, ℓo) be the irradiance variance of a monochromatic spherical wave of wavelength λ and wavenumber k = 2π/λ after propagating along a path of length L. The turbulence is assumed isotropic with refractive-index structure constant Cn2 and inner scale ℓo. Similarly let σ122(L, k1, k2, Cn2, ℓo) be the irradiance correlation, <(I1-) (I2-)>/ for iradiances I1 and I2 from spherical waves of wavelengths λ1, and λ2. Let σLA2(L, D, Cn2, ℓo) be the irradiance variance of radiation propagating along the same path and transmitted through a circular, uniformly-illuminated, phase-incoherent aperture of diameter D and measured using a receiving aperture of diameter D. It is assumed that D exceeds two Fresnel-zone sizes so σLA2 is approximately independent of the optical wavenumber.
The Effect of Line Mixing on Atmospheric Brightness Temperatures Near 15 μm
Authors: Strow L. Larrabee , Reuter Dennis
Published: February 2023

Rotational collisional narrowing, or line mixing, has recently been detected in the Q-branch spectra of two π − Σ bands of CO2 near 2000 cm−1 for both self- and N2-broadening [1,2]. The observed line mixing, which is caused by rotationally inelastic collisions that produce interference effects among overlapping lines during the absorption process [3,4] was found to alter absorption coefficients by as much as 65% in the wings of these Q-branches. This paper considers the influence of Q-branch mixing on atmospheric radiative transfer near the strong ν2 Q branch of CO2 at 15 μm.
Development of Coupled-Cavity Laser Diodes for Remote Sensing
Authors: DeFreez Richard K. , Elliott Richard A. , Puretz Joseph , Orloff Jon
Published: February 2023

Several recent developments in diode laser technology such as multiple emitter phase-locked arrays and epitaxial growth of materials that can be used to make lasers which emit at wavelengths ranging from the visible through the near infrared make these devices attractive candidates as sources for spectroscopic applications and remote sensing systems. The perceived advantages of diode lasers include efficiency, small size and weight, and direct modulation capability. But in fact mode hopping under current modulation, wavelength drift with temperature, and their relatively broad linewidths make conventional diode lasers less than ideal sources for laser spectroscopy. Elaborate stabilization schemes and external cavities are often used to overcome these shortcomings.
On Seeing a Vista - A Review
Authors: Walther Eric G.
Published: February 2023

This review seeks to assemble the methodologies and results of recent (1978-1981) studies of how people see a vista. The information is needed by federal and state personnel who are preparing regulations to protect visibility, required by the 1977 Clean Air Act Amendments. Some of this information may be helpful to those studying sky color, shadows, scattering and other topics in meteorological optics.
Scattering of White Light From a Cylindrical Bubble: Observation of Colors Near the Critical Scattering Angle
Authors: Marston P. L. , Johnson J. L. , Love S. P. , Brim B. L.
Published: February 2023

Phenomenologies of light scattering from liquid drops in air are well known because of meteorological manifestations (e.g. rainbows and glory) and because of practical applications.1 Effects of diffraction, interference, and focusing in scattering from bubbles in dielectrics (e.g. air bubbles in water, ice, and glass) have been only recently explored.2-7 A bubble, or bubble-like object, differs from a drop-like object in that the refractive index ni of the scatterer is less than the index no of the surroundings. As in the case for spherical drops,1 bubbles may have backward2,6,7 and forward2 glories enhanced by axial focusing (though the detailed descriptions differ from those for drops). There is an angular region of scattering unique to bubbles in which diffraction, interference, and dispersion are significant. This is the region near the critical scattering angle.2-5 In this paper we summarize the first observations of a novel effect of critical-angle scattering: the appearance of colored bands in the far-field scattering of white light.
Polarized light in Nature: a forgotten area in observational meteorological optics?
Authors: Können G.P.
Published: February 2023

Light is characterized by three properties: intensity, color and polarization. In meteorological optics, the first two have been studied intensively, since the human eye is very sensitive to intensity and color. On the other hand, we can hardly distinguish between polarized and unpolarized light. Because of this "polarization blindness", people are less familiar with the polarization of atmospheric optical phenomena (ref. 1,2).
Is the Horizon Visible from an Airplane?
Authors: Bohren Craig F. , Fraser Alistair B.
Published: February 2023

It has been pointed out that the distance to the visible horizon is increased by atmospheric refraction (French, 1982). Indeed, it even has been asserted that given the right vertical variation of refractive index a ray of light would have the same curvature as the earth, and the horizon would move to infinity; with a sufficiently powerful telescope, one could look around the earth and see the back of one's head (Jones, 1982).
Ice Crystals and Halos in Fairbanks, Alaska Ice Crystals and Halos at the South Pole
Authors: Tape Walter
Published: February 2023

During low level halo displays ice crystals in the atmosphere were collected and photographed. The halos were also photographed. The observed crystal shapes are used as inputs for theoretical computer simulations of the halo displays. Input crystal orientations are chosen to produce halo simulations approximating the observed displays. Especially when the crystal samples are homogeneous, one can sometimes learn the falling modes of the crystals. Also, the observed crystals and halos provide a test of the simulation predictions.
Continuous-Tone Mirage Images computed from Digitised Source Photographs
Authors: Lehn Waldemar H. , Wallace R. Edgar
Published: February 2023

The properties of mirage images corresponding to a given atmospheric model can be graphically summarised in two distinct ways: the image space1, and the transfer characteristic2. The former shows the apparent heights of surfaces of constant elevation, and is useful for estimating images of objects that possess considerable longitudinal extent, i.e. varying distance from the observer. The transfer characteristic is more convenient for objects concentrated near a single plane at a fixed distance from the observer. Detailed image construction, however, is laborious with both representations: typically, the points on a line drawing of the object are individually mapped into new apparent positions and joined by straight lines to create a line drawing of the image3. Entry of object data is slow; either individual x,y coordinates are entered by hand, or the object can be traced on a digitising tablet. Because the computed image is still only a line drawing, it is not entirely satisfactory. Certainly it is not convincingly realistic when compared with a direct photograph of a mirage.
Energy Distributions of Electronically Excited Molecules Produced by Ion Bombardment Of Silicon
Authors: Walkup R. , Avouris Ph. , Thomas IBM , Watson J.
Published: February 2023

A portion of the flux of sputtered particles produced during ion bombardment of a solid surface consists of molecular fragments. These sputtered molecules are of particular interest because they provide a unique probe of the dynamics of the sputtering process. In addition to center of mass motion away from the surface, the molecular fragments exhibit relative motion of the constituent atoms, e.g. rotations and vibrations. Concurrent measurement of the distribution of energy in these internal modes together with the center of mass kinetic energy enables critical evaluation of sputtering mechanisms.
Simultaneous Exposure of SiO2 and ThF4 to XeF2 and Energetic Electrons*
Authors: Loudiana M. A. , Dickinson J. T.
Published: February 2023

This study examines the effect of exposing thin films of SiO2 and ThF4 to gaseous XeF2 and energetic electrons. These systems are of interest to VLSI and optical coatings technology. The experiments were done in a stainless steel UHV chamber with Auger Electron Spectroscopy (AES) and Quadrupole Mass Spectroscopy capabilities. Changes in the mass of the thin films was measured with a sensitive, thermally stabilized quartz crystal microbalance. Details of the equipment and procedure are given elsewhere.1
High Resolution Electron Energy Loss Spectroscopy of Molecular Bond Weakening on Potassium Promoted Ru(001)
Authors: Hoffmann F. M. , dePaola R. A.
Published: February 2023

The adsorption of molecular nitrogen and carbon monoxide on potassium promoted Ru(001) has been investigated with vibrational spectroscopy, thermal desorption, LEED and work function measurements. For carbon monoxide, small precoverages of potassium result in anomalously weak C-O bonds which manifest themselves in large C-O stretch frequency shifts (600 to 1400 cm-1) and an increase in vibrational overtone anharmonicities[1]. Facile C-O bondbreaking was observed by isotopic scrambling in thermal desorption experiments. Both vibrational and thermokinetic data as well as analogies to metalcarbonyls[2] and molecularly adsorbed oxygen on Pt(111) [3] suggest a side-on bonding mode of the molecule with substantial weakening and lengthening of the C-O bond.
A Method for Initial Hypothesis Formation in Image Understanding
Authors: Lehrer Nancy Bonar , Reynolds George , Griffith Joey
Published: February 2023

One task in image understanding is to develop a mapping from some lowlevel abstraction to a higher level abstraction. One approach taken is to map from regions, lines, and/or surfaces to semantic labels. Achieving this task commonly involves developing a world model which defines semantic labels in terms of their lower level primitives. A matching scheme is then employed to calculate a match score between low level primitives and semantic labels, and some inference technique used to compare, contrast and combine match scores to create a consistent interpretation.
On Matching Deformable Models to Images
Authors: Terzopoulos Demetri
Published: February 2023

A crucial goal of machine vision is the computation of mathematical models describing the shapes of objects appearing in images. In this paper we formulate a broadly applicable class of models which may be viewed as deformable bodies composed of an abstract elastic material. The models are matched to images through the action of external forces which deform the bodies from their prescribed natural states and impart motions toward desired equilibrium configurations. Forces are typically derived from images, but they can also be applied interactively by the user (say, by means of a pointing device) or abstracted from physical phenomena (such as gravity).
Matching Deformable Models to Images: Direct and Iterative Solutions
Authors: Terzopoulos Demetri
Published: February 2023

In a companion paper [7] we formulate a broadly applicable class of mathematical models for describing the shapes of objects appearing in images. These models may be viewed as deformable bodies composed of an abstract elastic material. They are matched to images through the action of externally applied forces derived from image functions. Additional guiding forces may be applied interactively by the user. Three applications have served to illustrate the utility of the models: image based contour extraction, correspondence matching, and 3D object reconstruction. In the present paper, we deal with the discrete solution of the dynamical equations inherent to these applications. We focus on the direct and iterative numerical methods underlying our implemented algorithms for matching deformable models to images.
Intensity and Range Artifacts in Electronic Inspection
Authors: Donahue Joseph P.
Published: February 2023

The trend towards smaller linewidths and increased component placement accuracies in the fields of printed circuits and hybrid circuits is forcing inspection imaging systems to higher performance levels, especially in terms of resolution and accuracy. Additionally, 3D imaging has been found to greatly aid in the inspection of circuits bearing surface mounted devices. However, surface reflectance characteristics can greatly affect the accuracy of a linewidth or component height measurement. A one-dimensional model is introduced which explains one class of artifacts resulting from scattering of a gaussian beam within the illuminated material.
White Light Feedback Interferometry For Aberration Correction
Authors: Bold G. T. , Barnes T. H. , Somervell A. R. D. , Haskell T. G.
Published: February 2023

There has recently been considerable interest in a new type of adaptive optics system which uses intensity-phase feedback round a two beam shearing interferometer that is used to measure the shape of incoming wavefronts. Real-time aberration correction in monochromatic light has been demonstrated in the laboratory1,2. So far, the monochromaticity of these systems has been a severe limitation. Here we present a feedback interferometer system designed to work with broad-band light.
Psychophysical Techniques for Investigating Cone Kinetics
Authors: Burns Stephen A. , Elsner Ann E. , Lobes Louis A. , Doft Bernard H.
Published: February 2023

We have developed two noninvasive techniques, steady-state color matching and dynamic color matching, to investigate abnormalities in cone photopigment kinetics. Color matching is a psychophysical technique that reveals photoreceptor properties. Since color matching depends on the spectral sensitivity of the photoreceptors, the color match shifts when the optical density of the cones changes1,2.
Measurement of Color Thresholds
Authors: Gunkel R. D. , Roy M. S. , Roy A.
Published: February 2023

The description and measurement of defective color vision has been a problem of long standing for clinicians. Since subtle color defects are known to be correlated with some systemic disorders and toxic conditions, thresholds of discrimination for each color would be most informative, but neither they nor any closely related measurements are obtained by the conventional color tests. Louise Sloan in 1943 devised a Color Threshold Tester1 which was used briefly by the Air Force, but it was not widely accepted because of the cumbersome procedure involved and the lack of an effective data system. The so-called "New Color Test" of P. Lanthony2 undertook to determine thresholds of discrimination, which were plotted on the uniform chromaticity circle of Munsell to reveal a neutral zone or area. Unfortunately the test requires arrangement and scoring of 70 colored and gray caps or buttons, so it is nearly as tedious as the Farnsworth-Munsell 100-Hue test3. Sahlgren's Saturation Test4 is another attempt at determining thresholds, but it is limited to the blue and blue-purple part of color-space. Grützner5 demonstrated neutral bands in the visible spectrum of patients with acquired color vision defects, but his system was not easily adapted to clinical use. Marré6 used a modification of Wright's Trichromatic Colorimeter7 to measure the first saturation step from white throughout the whole spectrum, which is exactly what we would all like to do, but with a less complicated and time-consuming method. Herewith we are presenting Marré's type of data, which we obtained and plotted on a color circle with the chromagraph8. We believe that this circle concept is more acceptable to clinicians than either the conventional spectral sensitivity curves or the C.I.E. chromaticity diagram. The circle developed by the chromagraph has been confirmed mathematically and the colors calibrated by the Bureau of Standards, so threshold points on it can be transformed into C.I.E. coordinates if necessary. The system applies equally well to congenital and acquired color defects, but the distinction can usually be made without difficulty.
Macular function in normal aging: Loss of flicker sensitivity in two individuals
Authors: Eisner A.
Published: February 2023

We have initiated a study of normal aging in which data from a battery of visual function tests which have a high probability of monitoring the state of health of the outer retina are being obtained.
Image Processing in Ophthalmology A New Clinical Noninvasive Diagnostic Modality
Authors: Rehkopf Paul G. , Warnicki Joseph W. , Nelson Mark R. , Cambier James L. , Brown Stuart I.
Published: February 2023

A computer imaging system has been developed which acquires, archives, retrieves, processes and provides security for images derived during ophthalmic testing procedures. Film copies of the electronically stored or processed images may be made for publication, lectures or for a referring physician.
Effects of Intraocular Lens (IOL) Tilt and Displacement
Authors: Lakshminarayanan V. , Enoch J.M. , Raasch T. , Crawford B. , Nygaard R.W.
Published: February 2023

Postoperative astigmatism following intraocular lens (IOL) implantation has been found clinically (Jolson & Seidel, 1984) and has been discussed, for example, by Moore (1980), Binkhorst (1979) and Maltzman et al. (1983). Astigmatism, though primarily corneal in origin, may occur elsewhere along the visual axis including the lens implant and position of the fovea relative to the effective optic axis of the eye. Moore compared 100 IOL implant cases with 328 non-implant cases and found that postoperative astigmatism was proportionately far higher in the implant group. Tilting of the IOL was suggested as one of the factors which caused this astigmatism. Binkhorst also suggested that the astigmatism was purely optical. Miller & Doane (1984) presented evidence of tilt or wobble of iris-supported IOL’s due to rotation of the visual axis of the globe. We have determined tilt angle from postmortem cadaver eyes, and have computed the amount of spherical and cylindrical powers that are induced due to the tilt as well as that to lateral movement of the IOL.
Electrophysiological Assessment of Contrast Sensitivity in Human Infants
Authors: Norcia A.M. , Tyler C.W. , Allen D.
Published: February 2023

Assessment of visual function in human infants and pre-verbal children places the greatest demands upon test efficiency and non-invasiveness. The poor state of development of the behavioral response repertoire and attention span, and the impossibility of communication with the test subject through verbal instructions are each significant obstacles. These difficulties are unfortunately greatest during the critical period for visual development during which the human visual system is the most sensitive to disruption by exogenous factors, and at the same time most receptive to treatment.
Optokinetic Test of Infant Color Vision
Authors: Anstis Stuart , Maurer Daphne , Lewis Terri , Cavanagh Patrick
Published: February 2023

In adults, the luminous efficiency of colors provides a means of detecting color deficiencies. For example, green light looks dimmer to a deutan (green-blind) than to a normal adult. We used a new method to measure the luminous efficiency of red and green for 22 one- to three-month-old babies and for one three-month-old boy destined to be color-blind because of a deutan mother. The equiluminant points of the normal mothers and their infants were similar to each other but different from those of the deutan mother and her son. Our new method demonstrates the early maturation of some aspects of color vision, and can identify some color deficiencies in infants.
Stereoacuity: A Preliminary Comparison of VEP and Behavioral Thresholds
Authors: Odom J. Vernon , Chao Gung-mei
Published: February 2023

Stereopsis is one of the finest discriminations of the visual system. Not surprisingly, it is one of the discriminations most easily disrupted by abnormal visual experience. Therefore, tests of stereopsis have great premise as screening tests for abnormal visual function.
VER For Diagnosis of Functional Amblyopia in Disability Evaluation Referrals
Authors: Gretchen Van Boemel C.O.T. , Ogden Thomas E.
Published: February 2023

Social Security Benefits paid to the blind in the State of California cost tens of millions of dollars annually. In order to ensure that only the truly deserving receive benefits, strictly enforced criteria have been devised. Qualifications for disability based on blindness are determined by the Department of Social Services and the Disability Evaluation Department (1979). Qualifications include bilateral total ophthalmoplegia, visual field loss in which the widest diameter subtends an angle no greater than 20° and loss of central vision where visual acuity in the better eye after correction is 20/200 or worse.
Glare Disability Following Nd: YAG Laser Posterior Capsulotomy
Authors: Rehkopf Paul G. , Warnicki Joseph W. , Stuart John C. , Capone Antonio
Published: February 2023

Following extracapsular cataract extraction up to 50% of all patients have visual impairment from posterior capsule opacification. This opacification may be due to migration of residual anterior chamber epithelial cells onto the posterior capsule. There may also be a proliferation of scleral cells creating globular Elschnig pearls1,2.
Cone Optical Density in Retinitis Pigmentosa
Authors: Elsner Ann E. , Burns Stephen A. , Lobes Louis A.
Published: February 2023

We use two noninvasive, psychophysical techniques to study the foveal cones of patients with retinitis pigmentosa. The techniques, steady-state color matching and dynamic color matching, are based on the fact that a color match depends on the optical density of the photopigment contained in the cones1-4. Reduction of the number of cones or neural deficits will not affect the color match so long as the observer can do the task. These techniques provide estimates of 1) the optical density of the cones at a given retinal illuminance, 2) the illuminance that reduces optical density by half (the half-bleach illuminance or IO), and 3) the rate of change in optical density3-4. To examine patients with minimal cone damage, we recruit patients in the early phases of disease with good visual acuity, 20/20-20/50. Patients, aged 14-46, vary as to the inheritance pattern and age of onset of night vision problems. All have reduced amplitude or extinguished photopic and scotopic ERG responses.
Age-Related Color Vision Changes Comparing F-M 100-Hue, Lanthony Desaturated D-15, and Gunkel Chromagraph
Authors: Gunkel R.D. , Roy M.S.
Published: February 2023

There are reports in the literature1,2,3,4that sensitivity to color as assessed by the Farnsworth-Munsell 100-Hue Test5 deteriorates with age, except between the ages of 10 and 19 years, when it has been shown to improve. These age-related losses in color discrimination might be due to changes occurring in the retinal or neural systems, transparency of the media, or to the test methods themselves.
Automated Kinetic Perimetry: An Efficient Method of Evaluating Peripheral Visual Field Loss
Authors: Johnson Chris A. , Keltner John L. , Lewis Richard A.
Published: February 2023

Automated static perimetry has become a popular method of performing quantitative clinical visual field evaluations.1,2 Rapid staircase procedures now make it possible to obtain static perimetric threshold estimates (increment thresholds) at 60 to 80 locations in the central 30 degree visual field within 10 to 20 minutes.2,3 Although there can sometimes be appreciable variability associated with such abbreviated staircase procedures,2-4 they generally provide useful clinical information for detection and monitoring of glaucoma and other ocular disorders. High sensitivity and specificity can be achieved for automated static perimetry, especially when error-checking procedures are used during data acquisition and appropriate criteria are established for analysis and interpretation of results.
Spatio-Temporal Considerations in Multi-Flash Campimetry
Authors: Dixon Mike , Brussell Edward M. , White Charles W. , Muermans Myriam
Published: February 2023

Multi-flash Campimetry, a computer implemented, clinical psychophysical technique, can be useful for monitoring the residual vision of patients suffering from a variety of degenerative disorders such as multiple sclerosis (1-3), glaucoma (4), and macular degeneration (5). In its present form the methodology includes the presentation of 120 points of light arranged in 6 concentric circles such that the diameter of the largest circle subtends 40 deg. of visual angle at a viewing distance of 57 cm. A computer randomly selects one of these points, flickers it at 5 Hz, and progressively decreases the duty cycle (the proportion of a flicker cycle that is lit), beginning at 100%, in steps of no more than 2% until the flicker is detected. The form of flicker employed by the technique is of the classical variety in which a stimulus of constant luminance is turned on and off (i.e., 100% depth of modulation).
Saccadic Latency as a Measure of Afferent Visual Function
Authors: Brigell Mitchell
Published: February 2023

Sensitive measurement of optic nerve dysfunction can be of importance in the medical management of pituitary adenoma's and glaucoma and in the diagnosis of optic neuritis in patients with possible multiple sclerosis. Perimetry and pattern visual evoked potentials (PVEP) are standard clinical procedures for the assessment of afferent visual function. A unilateral delay in the PVEP provides a sensitive measure of optic nerve demyelination and is quite useful in the detection of clinically silent optic neuritis. However, the test is of limited value in monitoring progression of glaucoma and chiasmal compression because it does not allow for testing of individual points in the visual field. Perimetry provides a measurement of visual threshold for specific points in the visual field and is the standard test for following chiasmal compression and glaucoma, However, recent anatomic evidence has shown that changes in visual threshold may not occur until fairly extensive damage has occurred (Quigley et. al. 1982). We have used latency to initiate a saccadic eye movement to a visual target as a measure of optic nerve dysfunction with the notion that compression of optic nerve fibers will result in conduction delays that preceed changes in visual sensitivity. Preliminary data will be presented here which suggest that saccadic latency is a sensitive measure of afferent conduction.
Visual Acuity Measurement With a Second-Generation Scanning Laser Ophthalmoscope
Authors: Timberlake George T. , Peli Eli , Augliere Reed A.
Published: February 2023

Individuals with longstanding macular scotomas use an idiosyncratic, non-foveal retinal area adjacent to the scotoma to fixate and to inspect detailed visual stimuli (1). It is not known whether this preferred retinal locus (PRL) "selected” by the patient is the retinal area of highest residual visual acuity or how acuity is modified in retinal areas surrounding the scotoma. Because this information could be useful in visual rehabilitation of patients with macular disease we have developed a technique for measuring acuity at specific retinal loci using the Scanning Laser Ophthalmoscope (SLO) (2).
Evoked Potential Assessment of Cortical Adaptation
Authors: Seiple William , Kupersmith Mark , Nelson Jeremiah , Carr Ronald
Published: February 2023

The visual evoked response (VEP) is notoriously variable, in part due to adaptation. However, it has not been possible to express adaptation of VEP amplitude in terms of visual thresholds. We have employed a technique which makes it possible to rapidly measure contrast threshold elevations using evoked potential responses. The method can detect threshold elevation caused by as little as 20 sec exposure to faint contrasts of 5% or less. Threshold shifts are demonstrated here in both acuity limits and contrast thresholds. The effect is both orientation and spatial frequency selective. Patients with epilepsy, a disorder which probably reflects disabled cortical inhibition, fail to show this adaptation effect. Drugs which alter the brain dopaminergic system also effect adaptation.
Frequency-Doubling in the Visual Evoked Potential: Implications for Assessment of Spatiotemporal Vision
Authors: Previc Fred H.
Published: February 2023

Several investigators have noted that the suprathreshold visual evoked potential (VEP) characterizes spatiotemporal tuning in primates in different ways than do psychophysical measures. In particular, narrow spatial and temporal tuning (often surrounding multiple peaks) have frequently been observed (1), and in many cases, the peak of the spatial tuning function is higher than predicted behaviorally. One of the most intriguing aspects of the suprathreshold VEP is the frequency-doubling (i.e., predominance of power at twice the reversal frequency) which is observed when sinusoidal luminance-contrast gratings are used to elicit the VEP (2). Since the doubling phenomenon apparently does not occur when gratings are counter-phased using a square waveform, one hypothesis argues that the more gradual sinusoidal reversal dissociates the VEP onset and offset responses which are believed to combine during square-wave counterphasing (2,3). However, the fact that frequency-doubling does not typically occur in transcortical recordings from rhesus monkeys argues against this hypothesis.
Diurnal Rhythm in the ROD ERG in Retinitis Pigmentosa and CONE-ROD Degeneration
Authors: Birch David G.
Published: February 2023

Systematic variations in full-field ERG threshold have been reported in eyes of normal human subjects entrained to a 14 hour light: 10 hour dark daily cycle. Rod ERG thresholds were 0.13 log unit higher following light-onset than at other times of day (1). This threshold elevation is believed to reflect rod outer segment (ROS) shedding since the time course is similar to that documented in anatomical studies of shedding (2-4) and since neither rod responses of fellow eyes (1) nor rod responses in unentrained subjects (5) vary with time of day. The entrainment process takes 3 days, that is, by the third day of entrainment, the magnitude of the diurnal variation in rod ERG threshold is similar to that obtained following 7 or more days of entrainment (5). Light-onset is necessary to synchronize the rhythm since no increase in threshold is detectable at 9:30 am without light exposure at 8:00 am (5).
The Effect of Telescopic Spectacles on Visual Acuity During Head Motion
Authors: Demer Joseph L. , Porter Franklin I. , Goldberg Jefim , Jenkins Herman A. , Schmidt Kim
Published: February 2023

Telescopic spectacles are commonly prescribed to the visually impaired. However, many such low vision patients cannot use spectacle magnifiers effectively. This may be because these patients cannot maintain adequate stability of the magnified image on the retina during head movements. Head movements are the ubiquitous consequence of ambulation, tremor, and postural instability.
Contrast Sensitivity and Vernier Acuity After Resolution of Central Serous Chorioretinopathy
Authors: Rubin Gary S. , Lerner Brian C.
Published: February 2023

Central serous chorioretinopathy (CSCR) is a macular disease which predominately affects males 25 to 50 years of age. The disease is characterized by one or more focal defects or detachments of the retinal pigment epithelium (RPE) with a serous detachment of the overlying sensory retina. Visual symptoms include blurred vision, scotoma, metamorphopsia, micropsia, and color vision abnormalities. The patients frequently have reduced acuity, though seldom worse than 20/70.
Assessing Visual Function in Patients With Macular Edema
Authors: Rubin Gary S. , Sunness Janet S.
Published: February 2023

Diabetic retinopathy is a major cause of blindness throughout the world and diabetic macular edema (DME) is the leading cause of visual impairment in patients with diabetes. DME is a thickening of the sensory retina resulting from leakage of fluid from capillaries or microaneurysms. The fluid has a tendency to collect in the outer plexiform layer of the retina and may be accompanied by the deposition of hard exudates. The Early Treatment Diabetic Retinopathy Study (ETDRS) demonstrated that laser photocoagulation is an effective treatment for DME.1 The ETDRS based its conclusion on the finding that 24% of untreated eyes lose at least three lines of visual acuity (a doubling of the visual angle) while only 12% of treated eyes suffer the same loss, in a three year follow-up period. Eyes with more severe DME showed a greater treatment effect than eyes with milder DME.
Retinal Laser Doppler Velocimetry with a Near-Infrared Diode Laser
Authors: Riva Charles E. , Petrig Benno L. , Grunwald Juan E.
Published: February 2023

Laser Doppler velocimetry (LDV) provides noninvasive absolute measurements of the maximum (centerline) velocity, Vmax, of red blood cells (RBCs) moving in individual retinal vessels1.
Pattern Discrimination Perimetry and Conventional Perimetry in Early Glaucoma Detection
Authors: Drum Bruce , Severns Matthew , O'Leary David , Massof Robert , Breton Michael , Quigley Harry , Krupin Theodore
Published: February 2023

For the last several years,1,2we have been developing a new type of perimetry based on pattern discrimination instead of light detection. The test requires the patient to detect a patch of nonrandom dots (the "pattern") embedded in a surrounding field of random dots. We have argued that, in theory, this test should be more sensitive to early glaucomatous optic nerve damage than light detection perimetry because pattern detection requires cooperating responses from a number of neighboring ganglion cells, whereas light detection can be mediated by single ganglion cells.
Saturation Discrimination Losses: Similarities in Early Age-Related Maculopathy and Early Diabetic Retinopathy
Authors: Higgins Kent E. , Knoblauch Kenneth , Roy Monique , Gunkel Edmond Thall Ralph , de Monasterio Francisco M.
Published: February 2023

While age-related maculopathy (ARM) and diabetic retinopathy (DR) are distinct clinical entities, they are similar insofar as both can produce marked visual loss. In particular, both can produce an acquired blue-yellow, or tritan, color defect on a standardized test such as the Farnsworth-Munsell 100-Hue Test (1,2). In this study, we used a saturation discrimination test to compare the color vision of patients with early signs of ARM and patients showing early signs of DR.
Reading with the Rod Visual System
Authors: Chaparro Alex , Young Rockefeller S.L.
Published: February 2023

Much of the previous research on reading had been concerned with the illumination conditions that optimize performance. There is, however, a number of situations in industry where reading material of sorts is displayed at illumination levels much less than optimal for human observers.
Clinical Application of Temporal Modulation Sensitivity: Age Norms From Childhood to Maturity
Authors: Tyler Christopher W. , Clarke Maureen B. , Hawker Nina
Published: February 2023

Sensitivity to sinusoidal temporal modulation (flicker sensitivity) of a uniform stimulus field is proving to be a useful technique for application to ophthalmological diagnosis. When measured by varying the amplitude of the light modulation at a series of fixed frequencies, flicker thresholds provide measures of contrast sensitivity for the stimulus, as well as of the temporal response characteristic of the visual system. More than just another index of visual loss, flicker sensitivity has been shown in a variety of diseases to provide earlier detection than previous tests, to measure a reversible component of the visual susceptibility to disease, to provide differential diagnosis of otherwise similar conditions, to characterize the nature of the sensory deficit, and to provide information as to which retinal mechanisms are affected by the disease.
Evidence for a Neural Basis of Age-Related Visual Field Changes
Authors: Johnson Chris A. , Adams Anthony J. , Adams Craig W. , Lewis Richard A.
Published: February 2023

A number of investigations have reported reductions in visual field sensitivity as a function of increasing age in normal observers (Brenton and Phelps, 1986; Haas, Flammer and Schneider, 1986; Jaffe, Alvarado and Juster, 1986; Johnson, Post and Keltner, 1983). Although some studies have found slightly greater deficits for certain portions of the visual field, the major findings indicate a diffuse reduction in sensitivity for the entire visual field.
A model for the time course of photoreceptor loss in Retinitis Pigmentosa, as documented by Goldmann fields
Authors: Dagnelie Gislin , Massof Robert W.
Published: February 2023

One of the classical symptoms of Retinitis Pigmentosa is the gradual loss of vision in the periphery, first detected as a ring- or horseshoe-shaped scotoma in the mid-periphery. Using a Goldmann perimeter, such a scotoma can first be documented with small targets, e.g. II/4e. Subsequently it slowly increases in density and extent: a V/4e target may reveal the scotoma as much as ten years later than the II/4e target.
Normative Values for Visual Fields in 4 and 5 Year Old Children Using Kinetic Perimetry
Authors: Wilson Martin , Quinn Graham , Dobson Velma , Luna Beatriz , Breton Michael
Published: February 2023

Perimetry techniques are well developed for use in the adult population and provide valuable information about extent and changes in the visual field in ocular and neurologic disease. Kinetic techniques, in which a target of variable size and intensity are moved into the visual field were standardized by Goldmann in 1946 (1). However, most techniques are not approriate for use in young children and infants due to the complex nature of the responses required, but the information provided by perimetry is potentially as vital for pediatric patients as for adults.
Imaging of Visual Function Using ERG and VEP Responses
Authors: Sutter Erich E. , Tran Duong
Published: February 2023

The ERG and VEP responses have almost always been elicited with stimuli covering large areas of the visual field. Where small stimuli were used, usually only one or two areas could be tested at a time. These techniques impose severe limitations for research as well as clinical applications. The observed responses either represent a mean or a very small sample of responses in a two-dimensional field of highly variable response densities.
Theoretical Basis for A new Method of Reflection Oximetry and its Application to Retinal Vessels
Authors: Riva Charles E. , Mendel Mark J. , Petrig Benno L.
Published: February 2023

This paper proposes a new photometric method for the in-vivo measurement of hemoglobin oxygen saturation (OS) in retinal vessels and presents its theoretical basis. This method is based on the measurement of the Doppler shifted light that has been backscattered by the red blood cells moving in individual vessels.
Contrast Sensitivity Functions for Analysis and Simulation of Visual Perception
Authors: Peli Eli , Goldstein Robert B. , Young George M. , Arend Lawrence E.
Published: February 2023

The response of visual filters has been used to simulate vision and to design image enhancement techniques for the visually impaired. For the simulations and enhancements to be useful, they must be based on appropriate measurements of the filters being studied. Most previous measurements of spatial contrast sensitivity functions (CSFs) have been based on stimuli that give maximal contrast sensitivity. We measured CSF using stimuli that are better suited for analyzing perception of images. Use of the different types of CSF yields notably different simulations.
A visual test chart that "bypasses" the optics: Letters-in-Noise, Mark 2
Authors: Peili Denis G. , Jackowski Mary M. , Hoepner John A.
Published: February 2023

The typical patient for cataract surgery is elderly. Since cataracts are not life threatening, the decision to operate depends on a cost-benefit analysis. The cost is the relatively small risk of the operation. The benefit is improved vision, but that depends on the health of the rest of the visual system, which can be difficult to assess in the presence of the obscuring cataract.
Comparative Evaluation of Two Red-Green Color Vision Screening Tests
Authors: Severns Matthew L. , Drum Bruce A. , Massof Robert W.
Published: February 2023

Approximately ten percent of males in the United States and one half of one percent of females have a congenital red-green color vision defect. Detection of this defect early in life is important because school children with color vision defects can be as much as one year behind in learning ability when compared to their color-normal peers.2 Although the pseudoisochromatic plate tests (e.g. the Ishihara test) are quite sensitive when administered properly, many vision testers administer them under improper lighting conditions, leading to somewhat less reliable results. In addition, pseudoisochromatic plate tests are subject to fading from exposure to light and from repeated handling. We have evaluated two color vision screening tests which are suitable for use in large scale screening programs.