bluuebunny/crossref_metadata_2025 huggingface dataset:
Scotopic Perimetry Test for Early Glaucoma
Authors: Drum Bruce
Published: February 2023

Visual field measurement has long been considered the definitive test to distinguish glaucoma from ocular hypertension. However, recent clinical and histological studies1, 2 have shown that a large fraction of the optic nerve can be destroyed before visual field defects become apparent. Since glaucoma is a treatable disease, this finding underscores the need to develop more sensitive tests of glaucomatous optic nerve damage.
Interpreting the Stiles-Crawford Effect in Patients with Cataracts
Authors: Applegate Raymond A. , Massof Robert W.
Published: February 2023

Human photoreceptor alignment can be noninvasively studied by measuring the Stiles-Crawford effect (SCE). Typically, the SCE is measured by determining the relative efficiency of light in eliciting a visual response as a function of the locus of entry within the pupil (see Figure 1). Since the origin of the SCE is largely attributed to the waveguide nature of the photoreceptors, the SCE can be used to infer the principal alignment tendencies (peak of the effect) and distributive properties (width of the effect) of the population of photoreceptors under test.
Cortical activity localized by the Laplacian of the evoked potential field on the scalp
Authors: Srebro Richard
Published: February 2023

The Laplacian of the potential field on the scalp

∇
2

V=

∂
2

V

∂

x
2

+

∂
2

V

∂

y
2

, where V(x,y,t) is the time-varying potential field in x,y scalp dimensions, can be conveniently estimated using 5 electrodes arranged as a cross to measure the sum of orthogonal second differences (Laplacian derivation). The three concentric sphere model of the human head was used to assess some important properties. The Laplacian derivation may be represented by a spatial filter through which brain activity is "seen". The point spread function has a "Mexican hat" shape, or equivalently, brain activity is seen through a spatial bandpass filter different from that of a conventional, "monopolar", electrode derivation which approximates a lowpass filter. As the distance between the individual electrodes of the Laplacian derivation is made smaller, the peak spatial frequency increases, the bandpass narrows, sidelobes become increasingly prominent, and overall signal-to-noise decreases. At a distance of 2.5 cm between individual electrodes, the ratio of spatial resolution (approximately 2.0 cm, bandpass approximately .3 to 1.6 cycles per cm on the surface of the cortex) to signal-to-noise is nearly optimal. The Laplacian derivation is about ten times more sensitive to radially oriented than to tangentially oriented source-sink configurations. Thus, the Laplacian derivation has several useful attributes for localization studies, i.e. it is reference free, sensitive mostly to activity in the cortical mantle, has a resolution of 2 cm or better, and is insensitive to alpha activity. Because the passive properties of the head are nearly linear, no inversion of scalp potential field to yield a unique configuration of the underlying brain activity is in general possible without initial highly restrictive assumptions. But, the initial assumption required when the Laplacian derivation is used is relaxed to one concerning the dimension of the cortical region activated.
Spatial Frequency Discrimination in Amblyopia: A Comparison of Anisometropes and Strabismics
Authors: Yager Dean , Mathews Steven , Ciuffreda Kenneth J. , Ettinger Ellen Richter
Published: February 2023

Recent models of pattern vision have proposed that there are a number of individual neural channels, each selectively sensitive to a relatively narrow band of spatial frequencies. Together these channels act as a band-pass filter whose envelope is the spatial contrast sensitivity function of the visual system. The multiple spatial frequency channels model is invoked to account for a variety of visual experimental results.
Initial Results of Rapid Clinical Screening Using a New Contrast Sensitivity Vision Test Chart
Authors: Ginsburg Arthur P. , Evans David W.
Published: February 2023

Contrast sensitivity measurement is becoming increasingly important in diagnosising visual health and assessing task-related visual performance (1). Typically, only computer controlled video devices are generally available to measure contrast sensitivity. However, a new contrast sensitivity vision test chart was recently developed. That contrast sensitivity test chart can provide contrast sensitivity functions (CSF) similar to the video systems', but it is as quick and simple to use as present letter acuity charts (2). Normal population data has been obtained from this chart from 149 observers. Further, this chart has been tested in clinical settings and the resulting CFS's show characteristic losses for amblyopia, multiple sclerosis, cataracts, and glaucoma that are similar to those obtained using video systems. These initial results support the usability of the contrast sensitivity chart as a clinically valuable diagnostic tool.
Sensitivity of B-Cone Pathways of Diabetics Using a Simple Clinical Test
Authors: Adams Anthony J. , Zisman Frank , Ai Everett , Bresnick George
Published: February 2023

In our earlier studies we have shown that the sensitivity of the B-cone system may be selectively depressed as an early sign prior to the onset of diabetic retinopathy.1,2 Here we use a simple inexpensive clinical test, utilizing a 4 alternative forced choice method,3 to evaluate B-cone sensitivity in 47 diabetics with pre-proliferative and proliferative retinopathy. The test takes 3 to 4 minutes and includes measures designed to establish the specificity of the B-cone sensitivity loss and the role of changes in ocular media which might mimic B-cone sensitivity loss. This criterion free clinical test format appears to be a feasible approach to identifying early visual sensitivity loss.
Acute and Chronic Effects of Alcohol on Visual Evoked Potentials
Authors: Zemon V. , Camisa J. , Conte M.
Published: February 2023

Recent studies of the visual evoked potential (VEP) have applied techniques of systems analysis in an effort to measure response properties of sub systems within the visual pathways (7,8,9,10). These studies employed a radial spatial pattern and two types of temporal modulation conditions Superimposed and Lateral, which were designed to emphasize local excitatory and lateral inhibitory interactions, respectively. In addition, a set of two-sinusoid signals were employed in order to estimate the filter characteristics of an initial and late stage of linear processing. The data were interpreted in the context of a linear-nonlinear-linear (L1--N--L2) model of visual functioning. Preliminary clinical investigations have shown that these novel VEP measures may be able to diagnose certain types of idiopathic epilepsy (6), and to localize the neural deficits associated with multiple sclerosis (7).
Evaluating Metamorphopsia in the Presence of Ocular Opacities
Authors: Baraldi P. , Enoch J. , Savage G. , Fendick M.
Published: February 2023

Metamorphopsia refers to several forms of image distortion that patients with certain forms of central retinopathy and/or history of retinal detachment or tumor may experience. To help analyze these disturbances of visual function (as well as to delineate the bounds of central scotomas) the Amsler grid test is often employed. This test pattern is of little or no use in the presence of significant ocular opacities, however, because the grid lines become difficult to resolve.
Central and Peripheral Measures of Blue-Sensitive Pathways in Glaucoma and Ocular Hypertension
Authors: Heron Gordon , Adams Anthony J. , Husted Roger
Published: February 2023

It is well established that an acquired blue-dyschromatopsia is often present in glaucoma.1 In addition, foveal spectral sensitivity measures in glaucoma have shown that the chromatic pathways are affected (the short wavelength region being particularly depressed).2-5 Combined, these results suggest that the blue sensitive pathways are primarily at risk in glaucoma. A large body of data from color testing, in addition to measures of flicker sensitivity, provides us with considerable evidence that foveal function is abnormal in glaucoma, even when acuity is not affected.6-14 Even greater emphasis has been placed on foveal function in glaucoma since the startling report by Quigley, et al., that as many as half of the optic nerve fibers are destroyed before any abnormality in the visual field is detected.15
The Stiles-Crawford Effect in An Aniridic Observer
Authors: Lakshminarayanan V. , Enoch J. M. , Yamade S.
Published: February 2023

We present here measurements of the Stiles Crawford Effect (SCE) of the first kind in an adult observer with congenital aniridia. Some of these results have been presented elsewhere (Enoch, Lakshminarayanan and Yamade, 1985).
Studies of Artificial Scotoma Effects
Authors: Hammon Robert W. , Kelly D.H.
Published: February 2023

For the past two years we have studied the effects of artificial scotomas on several measures of the visual performance of normal subjects, using the SRI scotoma simulator described by Crane and Kelly (1983). This novel optical system locks the image of an opaque mask (of any luminance) in a fixed position on the subject's retina without interfering with retinal image motions produced by his normal eye movements. Thus, stimulus patterns are unavailable to the masked portion of retina, simulating a retinal scotoma. These studies included measurements of contrast sensitivity (with scotomas of various sizes and at different retinal locations), and tracking performance.
Human Macular Pigment Measured by Imaging Fundus Reflectometry
Authors: Alexander Kenneth R. , Kilbride Paul E. , Fishman Marlene , Fishman Gerald A.
Published: February 2023

Xanthophyll, a short-wavelength absorbing, non-bleaching macular pigment consisting primarily of lutein and zeaxanthin (Bone et al., 1985), may partially protect the foveal photoreceptors from light damage (Kirschfeld, 1982). For example, it has been suggested that the characteristic fundus pattern of bull’s eye maculopathies may be the clinical expression of this relative photoprotective effect (Weiter and Delori, 1986). It is of interest, therefore, to develop an objective, noninvasive technique for estimating the optical density of the macular pigment in the human eye.
Psychophysical Estimates of Human Macular Pigment
Authors: Pease Paul L. , Adams Anthony J.
Published: February 2023

We now know that the yellow macular pigment is localized in the inner and outer plexiform layers of the retina (Snodderly et al., 1984a) and that it is likely to be a mixture of two carotenoids: lutein and zeaxanthin (Bone et al., 1985). The yellow macular pigment may have a protective function (Kirschfeld, 1982), but it is generally thought to reduce the deleterious effects of chromatic aberration on foveal vision. Knowing the spectral absorption of the pigment in the living eye not only adds to our understanding of the pigment itself, in vivo assessment of the spectral properties and individual differences in density are necessary for many vision experiments for which it is important to correct for pre-receptoral spectral filtering.
Retinal Backscatter: studies with a confocal Scanning Laser Ophthalmoscope
Authors: Webb Robert H.
Published: February 2023

The confocal Scanning Laser Ophthalmoscope (cSLO) enables us to analyse in some detail the light scattered back from the retina. Surprisingly, light falling on the retina appears to be diffused within the various retinal layers to a distance of as much as 100 microns. This has significant impact on the design of imaging devices for the inside of the eye, and leads us to reassess the the images of the fundus which have been obtained by both traditional and novel means. If light diffuses sideways so much, how are we able to see with 20/20 (5 micron) acuity? And how much is the 'image' traditionally used in ophthalmic diagnosis modified from some ideal 'truth' to present the view understood by skilled observers?
Fundus Image Registration Algorithms for a PC-Based Image Processing System
Authors: Mitra Sunanda , Chandran Vinod , Krile Thomas F. , Lee Dah-Jye
Published: February 2023

Fundus photographs are routinely taken in an ophthalmology clinic to monitor feature changes in the suspected regions of the retina. For quantitative evaluation of subtle changes in the fundus from the photographs taken over a period of time using digital image processing, the fundus images have to be registered to a reference image, usually, the image of the same fundus taken earlier. The problem of registering one digital image with another reduces to that of finding local similarity between two structural data sets.
Comparative Norms & Screening Characteristics of Three Clinical Tests of Contrast Sensitivity
Authors: Shansky M.S. , Valella M. , Uniacke C.A.
Published: February 2023

Clinical tests of contrast sensitivity include micro-computer based devices and, more recently, a wall-chart version. While age norms and screening characteristics of some of these have been reported independently, no comparisons have been made of these tests using the same patients. In the present study, we have compared three such tests, including, two micro-computer based (Cadwell CTS 5000, for which no published norms exist, and the Optronix Series 200) as well as a wall-chart test (Vistech VCTS 6500). Our primary purpose was to compare age norms of all three tests as well as screening characteristics for several types of visual anomalies. We have found differences between the tests for both normal and abnormal patients, as described below.
Are There Perceptual Consequences of Vergence Anomalies?
Authors: Kelly S.A. , Teitelbaum B.A.
Published: February 2023

Forced changes in vergence by prisms and lenses are expected to be accompanied by perceptual changes in size and distance. For example, the application of base out (BO) prism is expected to induce convergence micropsia and a decrease in apparent distance.1 However, it has also been argued that a visually normal observer could perceive convergence micropsia and an increase in target distance, if perceived size is used as a distance cue.2 It has also been reported that 1/3 of a group of visually normal subjects could not use vergence information at all,3 giving rise to yet a third possible distance response to BO prism; no change. What kinds of vergence-mediated distance percepts do observers report in the absence of other cues? This question has been investigated both clinically and in the laboratory. Unfortunately, the clinical studies have carefully documented the distribution of responses, but have not obtained the data under controlled conditions. On the other hand, the classic investigations of vergence effects on perception have generally only reported group data and ignored the clinical implications of response variability. Thus our first goal was to measure the distribution of size and distance responses to forced vergence changes induced by both prisms and lenses.
Acuity Card Assessment of Visual Acuity in High-Risk Infants: Interobserver Agreement in a Subjective Test Procedure
Authors: Dobson V. , Carpenter N.A.
Published: February 2023

The acuity card procedure (McDonald et al 1985; 1986a,b) was developed to be a rapid procedure for the measurement of grating acuity in infants and young children. It is a modification of the forced-choice preferential looking (FPL) procedure, a laboratory-based procedure for the objective measurement of visual function in non-verbal subjects (Teller 1979).
Fatigue Effects in Automated Perimetry
Authors: Johnson Chris A. , Adams Craig W. , Lewis Richard A. , Keltner John L.
Published: February 2023

Automated static perimetry has improved the detection and differential diagnostic capabilities of clinical visual field testing. However, automated perimetry is more demanding and less flexible than manual visual field testing. The increased effort and attentional requirements of automated perimetry may adversely influence the sensitivity and reliability of visual field testing.
Spatial and Temporal Deficits in Multiple Sclerosis
Authors: Brussell Edward M. , Dixon Mike
Published: February 2023

It is new well documented that an attenuation of spatial contrast sensitivity is to be expected in most multiple sclerosis (MS) patients (1-3). Further, it has been reported that patients contrast sensitivity functions can be influenced by modulating the grating in time as well as in space (4-7). The specific consequences of using flickering gratings, however, has been a matter of some conjecture. For example, Marx et al. (5) concluded that temporally modulating stimulus gratings causes a uniform reduction in contrast sensitivity across all spatial frequencies, while Medjbeur and Tulunay-Keesey (6) concluded that flickering the grating stimuli caused a number of distinct deficit patterns to emerge. Although these discrepancies could be due to the way in which the pathology manifested itself in the particular groups of patients sampled in these studies, they may also have been due to the uncontrolled and unknown response criteria that were adopted by the observers (8). An example of how this factor can influence the conclusions that are drawn has been offered by Brussell et al. (2). They observed similar contrast sensitivity deficit patterns in 15 MS patients for both flickering and non–flickering grating stimuli. The most parsimonious explanation of these data was that a single diseased pathway was carrying information about both the spatial and temporal characteristics of the stimulus. In addition to assessing contrast sensitivity, observers were also asked on each trial to state whether detection was based upon seeing a pattern or upon seeing flicker. A summary of these data indicated that the patients reported detecting patterns more often than controls. This additional information led to quite a different conclusion: the patients relied upon the output of a pattern mechanism more often than the controls because it was less impaired than a mechanism responsible for processing information about flicker.
New Scheme for Analyzing Vitreous Fluorophotometry (VFP) Scans
Authors: Bungay P.M. , Roy M.S. , Bonner R.F.
Published: February 2023

The shape of a VFP measurement scan depends in a very complicated way upon the condition of the blood-retinal barrier and a variety of other factors, such as the elapsed time after administration of the dye, the manner of dye administration, the character of the vitreous, optical properties of the eye, and the design of the instrument. Existing schemes for analyzing vitreous fluorophotometry scans suffer from deficiencies in the ways they do, or do not, take these influences into account. We report the development of new methodology for scan interpretation. Improvements over existing analysis schemes are discussed.
Fundus Photoperimetric Analysis of Pigmented Chorioretinal Lesions
Authors: Enoch Jay M. , Lakshminarayanan Vasudevan , Savage Gary L. , Knowles Richard A.
Published: February 2023

This is a preliminary study intended to consider assessment of fundus reflectometry in the infrared spectrum. This point was originally made by Ernest (1). Development of the techniques he proposed has not progressed to the point of optimum utilization (2-6).
Retrospective Analysis of Factors Predicting Functional Success in Telescopic Spectacle Use by Low Vision Patients
Authors: Demer Joseph L. , Porter Franklin I. , Goldberg Jefin , Jenkins Herman A. , Schmidt Kim , Ulrich Imogen
Published: February 2023

Telescopic spectacles are frequently prescribed for visually impaired patients, but clinical observation reveals that low vision patients often do not achieve expected functional use of these costly visual aids. This may be a result of patients’ inability to maintain adequate stability of magnified images on the retina during unintended head movements caused by ambulation, tremor, and postural instability. Although the visual-vestibulo-ocular reflex (VVOR) produces eye movements that partially compensate for head movements, this compensation is incomplete when images are magnified by head-mounted telescopes.1 It has been demonstrated in normally sighted subjects wearing telescopic spectacles that head motion significantly decreases dynamic visual acuity (DVA), the acuity during head motion.2 We hypothesized that insufficient compensation of head instability might cause reduced DVA and motion sickness, and might thus predict failure of low vision patients to make functional use of telescopic spectacles. We have been testing this retinal image instability hypothesis to develop methods that may be useful in prediction of the successful use of telescopic spectacles.
Increment Threshold (tvi) Data and the Site of Disease Action
Authors: Hood D.C. , Greenstein V.C.
Published: February 2023

Retinal diseases decrease the sensitivity of the visual system. A variety of psychophysical techniques have been employed to test competing hypotheses as to the site and mechanism of disease related sensitivity loss. Although there has been considerable analysis of increment thresholds on flashed backgrounds1,2,3,4, surprisingly little theoretical use has been made of standard increment threshold (tvi) curves5,6. Here we propose a conceptual framework for using (tvi) data to test whether the primary disease defect is at the level of the receptors.
Vision Function of Rod Monochromats: I. Advanced Clinical Measures
Authors: Haegerstrom-Portnoy G. , Friedman N. , Adams A.J. , Schneck M. , Hewlett S.
Published: February 2023

Achromatopsia -- the absence of color vision -- is a relatively rare condition which can result from a variety of congenital and acquired ocular disorders. The most common form of achromatopsia is complete (typical) rod monochromatism, which is inherited as an autosomal recessive trait and is characterized by severely reduced visual acuity, pendular nystagmus and photophobia. X-linked recessive incomplete (blue cone) monochromatism, in which the patient has both rod and blue cone function, has a very similar presentation clinically, and is often confused with complete rod monochromatism. Less common etiologies include autosomal recessive incomplete achromatopsia (red or green cone function only) and a number of acquired cone and rod-cone dystrophies and degenerations; any of these conditions may present with varying degees of color vision loss, acuity loss, photophobia and nystagmus. From a clinical standpoint, the correct diagnosis of an achromat is necessary for appropriate patient managment and, with hereditary forms, genetic counseling. Yet most practitioners base their diagnosis of rod monochromacy on a minimal amount of information.
Foveal Flicker Sensitivity: Pupil Size and Aging
Authors: Mayer Melanie J. , Kim Charlene B. Y.
Published: February 2023

Changes in retinal health with aging or disease may affect an observer’s ability to detect flickering light.1,2,3 The de Lange function4 describes an observer’s contrast sensitivity to various rates of sinusoidal flicker and, with the addition of a nonlinearity, can account for all traditional flicker fusion data.5 We present data showing the effects of healthy aging on de Lange functions.
Assessment of Spatiotemporal Contrast Sensitivity in Retinitis Pigmentosa
Authors: Pulos E. , Ruther K. , VerHoeve J. , Bresnick G.
Published: February 2023

It is important to characterize with precision the nature of vision loss that accompanies disorders of the retina. Conventional clinical tests of vision cannot always capture the details of vision loss. In retinitis pigmentosa (RP), for example, the ERG response is often abolished while visual acuity is unaffected. These tests are either too sensitive (ERG) or not sensitive enough (acuity) to monitor disease progress or to evaluate severity.
"Saturation" of the Dark-Adapted b-Wave
Authors: Peachey Neal S. , Alexander Kenneth R. , Fishman Gerald A.
Published: February 2023

Luminance-response functions of the dark-adapted ERG b-wave have been previously described by the Naka-Rushton equation R/R
max
= L
n
/(L
n
+ K
n
), in which R is the response to a stimulus of luminance L, R
max
is the maximum response amplitude, K is the luminance required to achieve a response one-half the amplitude of R
max
, and n is a dimensionless slope constant (1,2). However, when recording from normal observers and from patients with retinal disorders, we have observed that the Naka-Rushton equation does not represent the entire b-wave luminance-response function. Instead, our functions are composed of two distinct limbs. One limb appears to saturate at the luminance levels reported previously (1). However, as flash luminance increases above this level, a second limb appears. In the present report, we document the non-monotonic nature of the b-wave luminance-response function and examine possible explanations for the high luminance limb by recording ERGs from selected patients.
A Theoretical Interpretation of ERG Abnormalities In Central Retinal Vein Occlusion
Authors: Johnson Mary A. , Hood Donald C.
Published: February 2023

Central retinal vein occlusion (CRVO) is a disorder in which the circulation to the inner retina is impaired because of a blockage of the central retinal vein. The occlusion can produce severe inner retinal ischemia, leading in some patients to the blinding complication of neovascular glaucoma. In these patients, the choroidal circulation, which serves the photoreceptors, is not impaired. Several types of changes are seen in the electroretinogram (ERG) of patients with CRVO. Sabates and his associates1 have reported preferential reductions in the b-wave amplitude relative to the a-wave amplitude in CRVO eyes that develop iris neovascularization. Johnson and co-workers2 have measured ERG intensity-response functions in patients with CRVO and have analyzed the b-wave amplitudes by fitting the data with the Naka-Rushton function: (1) where I and R are intensity, response ordered pairs, Rmax is the maximum b-wave amplitude (measured from the trough of the a-wave to the peak of the b-wave), K is the half-saturation constant (because when I = K, R = 1/2 Rmax) and n is the slope. In normal observers, these parameters vary independently.3
Application of Signal Detection Theory to Evaluation of Clinical Tests
Authors: Klein Stanley A.
Published: February 2023

Several authors have proposed using signal detection theory for assessing the value of different clinical tests (Swets and Picket, 1982; Daubs, 1983). Two years ago at the Second Noninvasive Meeting, Masoff (1986) introduced this area of concern to our group. He argued that a criterion-free index is needed for assessing the value of a diagnostic test. He proposed using the area under the ROC curve as such an index. My paper is devoted to three aspects of this topic. 1. The dependence of d' on criterion. 2. The advantages and disadvantages of using the ROC area. An important element missing from the ROC area is the notion of a cost-benefit analysis of the test results. Cost-benefit considerations are much more important for diagnostic tests than for basic research, especially when the ROC curve deviates strongly from that expected for equal variance Gaussian distributions. 3. Optimal combination of the results of several tests. How, for example, should one combine information about the intraocular pressure, disk cupping and disk pallor in order to obtain a single index for glaucoma susceptibility. This is a difficult problem because any given disease may exhibit very different symptoms and the test results may have to be combined in a highly nonlinear fashion. The knowledge and intuition of a glaucoma expert should be incorporated into our algorithm for combining test results. Surprisingly, the ROC area has a relatively straightforward extension to multiple tests.
Spectral Laminography of Subretinal Neovascular Membranes
Authors: Rapkin Jeffrey S. , Nussbaum Julian J.
Published: February 2023

Subretinal neovascularization occurs in association with age-related maculopathy, histoplasmosis, angioid streaks, trauma and myopia.1 Other less common associations include optic nerve head drusen, choroidal tumors, pigment epithelial hamartomas, photocoagulation, rubella retinopathy and various inflammatory disorders such as multifocal posterior pigment epitheliopathy and Harada's disease.1 The clinical appearance of subretinal neovascularization is a dirty gray or green discoloration at the level of the retinal pigment epithelium.1,2 New vessel growth may be accompanied by a serous, exudative or hemorrhagic detachment of the retinal pigment epithelium or neurosensory retina. Early treatment of neovascular membrane by laser photocoagulation has been shown to be of benefit in limiting vision loss for some patients.3,4 Prompt recognition and localization of the neovascular process is essential for successful treatment. Fluorescein angiography is the standard method used to confirm the presence and anatomical location of subretinal neovascular membranes.1,2,5,6
Retinal Densitometry in Acute Posterior Multifocal Placoid Pigment Epitheliopathy
Authors: Keunen Johan E.E. , van Meel Gerard J. , van Norren Dirk , Smith Vivianne C. , Pokorny Joel
Published: February 2023

Cone photopigment kinetics were investigated using retinal densitometry in six patients with acute posterior multifocal placoid pigment epitheliopathy (APMPPE). Our goal was to elucidate cone impairment during a period of 12-18 months following the onset of the disease process.
Further Investigation of Contrast Sensitivity and Visual Acuity in Pilot Detection of Aircraft
Authors: O’Neal Melvin R. , Miller Robert E.
Published: February 2023

Contrast sensitivity testing has been reported to be useful in the detection and monitoring of certain ocular conditions. Also, for individuals with normal visual acuity, Ginsburg et al. (1983) stated that contrast sensitivity, rather than visual acuity, was strongly related to pilots’ aircraft detection performance. However, their results show that over the 10 test days there was a lack of consistency for the contrast sensitivity any particular spatial frequency to correlate with detection distance, even between days with similar visibility conditions. In a simulator study, Ginsburg et al. (1982) reported that pilots’ scotopic contrast sensitivity correlated with detection of an aircraft on a runway. In this study, however, three visibility conditions (day, night, and fog) were used but the only correlation reported was between the peak of the scotopic contrast sensitivity and detection of a Mig at the end of a runway under low visibility, presumably fog. Both studies measured contrast sensitivity using the method of increasing contrast, which is known to be influenced by individual threshold criterion (Higgins et al., 1984), and may have lead to criterion-influenced correlations.
Automated Pupil Perimetry
Authors: Kardon Randy H. , Haupert Chris , Thompson H. Stanley
Published: February 2023

Objective tests of visual function are reliable indicators of disease and are not influenced by a patient's fears and biases. Unfortunately, there are few such tests available. We were interested in testing the feasibility of using automated pupil perimetry as an objective means of assessing the visual field. Although previous attempts at pupil perimetry did suggest it could be used to assess afferent visual function, the lack of a sensitive means to quantitate the pupil response, automatically analyze it, and produce a reproducible, automated, stimulus source has kept it from becoming a useful clinical and research tool. In order to overcome these problems we developed 1) the instrumentation to accurately quantitate changes in pupil area, 2) a software program to collect the data and analyze it with respect to various response parameters (ie change in pupil area and latency time), and 3) a link between an automated perimeter (the Humphrey Field Analyzer) and a computer-based pupillometer. By using the Humphrey Field Analyzer, we were able to compare focal pupil responses to static visual threshold testing in the same subject.
Retinal Reattachment of the Human Macula Assessed by Imaging Fundus Reflectometry
Authors: Morimoto David , Keehan Kathleen M. , Kilbride Paul E. , Blair Norman P.
Published: February 2023

Visual recovery following retinal reattachment surgery may be limited by a number of factors. Detachment of the macula is the most important of these, often yielding poor visual acuity after an anatomic success. Gross morphologic changes giving a poor visual result include macular pucker, cellophane maculopathy, cystoid macular edema, and subretinal fibrosis. Some cases with a normal appearing macula by ophthalmoscopy have reduced visual acuity, and these have been attributed to misalignment of photoreceptors, faulty regeneration of photoreceptors, or RPE atrophy (4,5,6). Histologic animal studies have shown degeneration of photoreceptor outer segments following retinal detachment with gradual regeneration following reattachment (2,8). In this report we use fundus reflectometry in vivo to compare the spatial distribution of the visual pigments, contained in photoreceptor outer segments, in 3 patients following retinal reattachment surgery with 9 controls.
The Influence of Simulated Nystagmus Parameters on Visual Acuity
Authors: Currie Debra C. , Bedell Harold E.
Published: February 2023

In persons with congenital idiopathic nystagmus, a target's image undergoes substantial retinal motion. Although visual acuity is often reduced in these individuals, the magnitude of the reduction is typically fairly modest. In an attempt to determine what accounts for the visual loss, and therefore what the potential for improvement is, researchers have looked at the relationship between acuity and various parameters of the nystagmus eye movements.
Analysis of tritan detection thresholds and discrimination errors
Authors: Pokomy Joel , Smith Vivianne C. , Yeh Tsaiyao
Published: February 2023

The Type III acquired blue yellow color vision defect is characterized by failure of screening plates (e.g. the Standard Pseudo-isochromatic Plates, Part II) and an accumulation of errors on the Farnsworth-Munsell 100-hue test. Recent studies of acquired color vision defects have included specialized tests of increment detection for the isolated S (Short Wavelength Sensitive) cone system. A puzzling aspect in at least one such study was the lack of correlation between evidence of S cone loss on increment detection and evidence of S cone loss on the FM-100-hue test1. The purpose of this paper is to attempt to reconcile these findings, and to provide a unified framework for analyzing detection and discrimination data.
Theoretical Evaluation of S-Cone Pathway Sensitivity Losses In Diseases of The Visual System
Authors: Massof Robert W.
Published: February 2023

Several recent studies have focused on the vulnerability of the S-cone pathway to visual system diseases. Selective or preferential S-cone pathway defects have been reported in diabetic retinopathy, age-related macular degeneration, retinitis pigmentosa, and glaucoma, to name but a few. Conclusions about Scone pathway defects in these disorders have been drawn from threshold versus wavelength measures (i.e., increment threshold spectral sensitivity), heterochromatic threshold versus radiance functions (ala Stiles pi mechanisms), heterochromatic visual acuity under conditions where contrast favors S-cones, and flicker versus flashed heterochromatic increment thresholds. These various methods rely on the presumed high chromatic gain and coarse spacetime resolution of the S-cone pathway.1-2
Perceptual Adaptation to Distortions Produced by Meridional Magnifying Lenses
Authors: Govender Sivagami , Bedell Harold E.
Published: February 2023

Many patients report perceptual distortion and symptoms of discomfort when spectacle lenses are first worn or when a significant change is made in the prescription. Clinical observations indicate that, after a period of lens wear, most patients experience less distortion, suggesting that adaptation has occurred. The rapidity and completeness of this adaptation depends apparently upon the type of spectacles worn (and, hence, the distortions induced), as well as characteristics of the individual that, as yet, are not well understood.
A Sensitive Test of Disability Glare
Authors: Bailey Ian L. , Bullimore Mark A.
Published: February 2023

Visual acuity alone is a poor indicator of visual performance in patients with media disturbances. Hess and Woo (1978) demonstrated that cataract patients with similar levels of visual acuity could have markedly different contrast sensitivity functions. It has been suggested that the detrimental effect that lens opacities have on vision can be better evaluated by the assessment of disability glare. Disability glare causes a reduction in visual performance that results from intraocular light scatter reducing the contrast of the retinal image. Disability glare is assessed by determining the extent to which the introduction of a bright light source close to a test target impairs the visibility of that target. Paulsson and Sjostrand (1980) found that cataractous patients who had good visual acuity and only moderately reduced contrast sensitivity under normal testing conditions, showed severe contrast sensitivity deficits in the presence of a glare source.
Measurement of Photostress Recovery Time with New Instrumentation
Authors: Newsome David A. , Blacharski Paul A. , Hinrichs Clay
Published: February 2023

Photostress testing can provide information not visible by ophthalmoscopy and can be used to detect early macular disease and possibly detect recovery prior to visual improvement.1Recovery times have been variable even in groups of age-matched normals.2 3Macular photostress recovery tests must be reproducible, easy to perform with good patient compliance, and require a minimal amount of time and space. We report our experience with a new instrument designed by one of the authors (PB), testing 90 normal individuals and groups of patients with drusen, macular degeneration or diabetic retinopathy.
Maturation of the Oscillatory Potentials of the Human Electroretinogram
Authors: Birch Eileen E. , Birch David G. , Uauy Ricardo D.
Published: February 2023

Oscillatory potentials (OPs) of the electroretinogram appear to be generated within the inner nuclear layer of the primate retina1 and integrated at the level of the Mueller cells2, where the b-wave originates. OPs have been shown to be useful in the diagnosis, management, and/or clinical investigation of retinal diseases, including diabetic retinopathy3,4, hereditary retinal degenerations5, and congenital stationary night blindness6. Abnormalities of OPs may reflect photoreceptor damage (abnormal signal provided to the inner retinal circuitry), inner retinal damage, or both.
Vernier Thresholds and Positional Bias in Normal, Suspect and Glaucomatous Eyes
Authors: Piltz Jody R. , Swindale Nicholas V. , Drance Stephen M.
Published: February 2023

Vernier acuity is a hyperacuity task which involves the ability to perceive a disparity in the relative location of two elements of a target. The term hyperacuity was coined by Gerald Westheimer because thresholds to these targets are substantially lower than thresholds to Snellen type targets (minimum resolvable acuity). Prac­ticed normal observers can detect vernier offsets of 2 to 10 seconds of arc, compared with normal Snellen thresholds of 30 to 60 seconds of arc. (Westheimer, 1981). Vernier acuity determinations require striatal integration of information from adjacent or overlapping receptive fields (Braddick, 1984; McKee and Levi, 1987; Westheimer and McKee, 1977).
Aging and the Hyperacuity Gap Function
Authors: Lakshminarayanan V. , Aziz S. , Enoch J.M.
Published: February 2023

Hyperacuity is defined as the ability to perceive a difference in relative spatial localization of 2 or more visual stimuli to the order of 3 - 8 seconds of arc (Westheimer, 1979). The two dot vernier task is an example of a hyperacuity task. Hyperacuity stimuli are highly resistant to retinal image degradation and are, therefore, of clinical importance as a test of visual function in patients with partially opaque media or scattering bodies (see Enoch, et al., 1985 for a review). Hyperacuity techniques do not require a window through the anomalous media.
The Texas Sandwich: A New Low-Anxiety Corneal Electrode for Electroretinography
Authors: Baitch Lawrence W. , Sanders N. Bradley
Published: February 2023

Although ERG recording is a routine clinical procedure performed in nearly every ophthalmology clinic, it is perhaps one of the most invasive of the "noninvasive" techniques for assessment of the visual neurosensory pathway. Anxiety and discomfort caused by the recording apparatus and often intimidating ERG stimuli can induce detrimental artifacts or otherwise yield data unsuitable for making diagnostic decisions. Pediatric patients are particularly problematic in this regard.
Discriminating Arm-Risk from Healthy Eyes Using Foveal Flicker Sensitivity
Authors: Spiegler Shari J. , Mayer Melanie J. , Ward Brian , Glues Andrew , Kim Charlene B. Y.
Published: February 2023

Can flicker sensitivity testing be used to detect early stages of retinal dysfunction which eventually lead to exudative age-related maculopathy (ARM)? As a first approximation to answering this question, we tested whether flicker sensitivity of the "good" eye of patients with monocular exudative ARM can be discriminated from age-matched healthy eyes. We define these "good" eyes as ARM-risk because exudative ARM is usually binocular, but a few years may elapse between appearance of symptoms in the first and second eye.1,2 Early detection would facilitate early treatment with known methods, i.e. laser surgery to limit the extent of visual loss, and may prove useful in the evaluation of potential treatment methods.
Nerve Fiber Layer Assessment with a Retinal Laser Ellipsometer
Authors: Dreher Andreas W. , Reiter Klaus
Published: February 2023

Retinal ganglion cell axons form the innermost layer of the retina known as the nerve fiber layer. These axons converge to form the optic nerve, which transmits the visual image from the eye to the brain. In glaucoma, there is damage to these nerve fibers as they leave the eye through the lamina cribrosa, a fenestrated network of connective tissue. In the retina, the nerve fibers spread out in a thin layer creating a characteristic fingerprint. It is likely that loss of even a few axons can alter the fingerprint and be observed in the retinal nerve fiber layer when appropriate techniques are used.
Laser Doppler Velocimetry in Episcleral Vessels: Light Scattering Process
Authors: Petrig B.L. , Lanuti M. , Riva C.E. , Schwartz. B.
Published: February 2023

The episcleral vessels provide circulation to the anterior surface of the front of the eye. The episcleral veins are the main channels for drainage of aqueous humor from the eye. Increase in pressure in these veins can produce a form of glaucoma with increased pressure in the eye.1 Determination of blood flow in the episcleral vessels may be useful for the study of the pathophysiology of a number of clinical ocular entities and may help in the early diagnosis of such disorders.
Cone Photopigment Density in Aging and AMD
Authors: Burns Stephen A. , Elsner Ann E. , Weiter John J. , Kreitz Mark R.
Published: February 2023

Age-related Macular Degeneration (AMD) is the leading cause of vision loss in the elderly. Histopathologically AMD is characterized by diffuse changes in Bruch’s membrane and in many cases by the development of drusen. The pathogenesis of AMD is thought to derive from abnormalities of the Retinal Pigment Epithelium (RPE). The RPE is critically important for the nourishment and health of the photoreceptors. For this reason we are using a psychophysical measure of photoreceptor function to examine patients with AMD. The measure used is the change in the color-match with retinal illuminance which provides information on the optical density and regeneration of the cone photopigments.
The Effect of Cataract Type on Glare and Contrast Sensitivity
Authors: Rubin Gary S. , Adamsons Ingrid A. , Taylor Hugh R.
Published: February 2023

It is well established that visual acuity underestimates visual impairment due to mild cataract. The principal effect of a cataract is presumed to be an increase in intraocular light scatter which acts as a veiling luminance to reduce retinal image contrast. Glare and contrast sensitivity tests are more sensitive to the effects of intraocular light scatter than tests of visual resolution (acuity), and have been widely promoted for the evaluation of cataracts. In a recent study, Elliott et al1 reported that posterior subcapsular cataracts (PSC) differed from other cataract types in causing greater loss of contrast sensitivity at low spatial frequencies and greater sensitivity to glare. The purpose of this study is to investigate how different types of cataract affect glare and contrast sensitivity.
Simulating light scatter in healthy, ageing eyes
Authors: Elliott David B , Whitaker David
Published: February 2023

A major issue in vision in ageing research is how to distinguish between the effects of changes in the optical and neural systems of the eye on the decline in visual function with age (Sekuler et. al., 1982). Much controversy has arisen with regard to the principal cause of the decline (see Elliott et. al., 1990). The major optical changes occurring with increasing age are reduced retinal illumination and increased light scatter. The first of these is caused by a reduction in pupillary diameter with age (senile miosis) and increased lenticular light absorption. In a previous study we mimicked these changes using the miotic 0.125% Thymoxamine Hydrochloride and a 0.2ND filter, and measured the contrast sensitivity (CS) of a group of young observers both with and without these simulations (Elliott et. al., 1990). We found no significant change in sensitivity and concluded that these optical age changes had no effect on the well-documented decline in CS with age.
Spatiotemporal Contrast Sensitivity for Sloan Letters and D6 Patterns
Authors: Alexander Kenneth R. , Xie Wei , Derlacki Deborah J.
Published: February 2023

In the study of visual disorders, contrast sensitivity has been measured with both windowed sinusoidal gratings and with letters. It has been suggested that contrast sensitivity functions for both types of stimuli are quite similar (e.g., Legge et al., 1987; Herse and Bedell, 1989), although comparisons have not been made under comparable conditions. While sinusoidal stimuli are advantageous for studying spatial mechanisms, letters are more familiar to patients, contain multiple orientations, are less subject to spurious resolution and are more affected by sampling irregularity than are gratings (Herse and Bedell, 1989), all of which suggest that the measurement of contrast sensitivity for letters may have an advantage in detecting visual abnormalities. However, letters contain a broad range of spatial frequencies (Parish and Sperling, 1991) which potentially complicates the interpretation of test results using these stimuli.
Effects of Distortion Due to Image Enhancement on Face Recognition
Authors: Peli Eli , Young George M. , Lee M. Estella , Trempe Clement L.
Published: February 2023

The loss of sensitivity at high spatial frequencies and the difficulties that many low-vision patients have in recognizing faces led us to test and demonstrate that (nonlinear) highpass filtering of images may improve recognition of faces (Peli et al, 1991a).