bluuebunny/crossref_metadata_2025 huggingface dataset:
Extracting Thresholds from Noisy Psychophysical Data
Authors: Swanson William H. , Birch Eileen E.
Published: February 2023

Psychophysical measurements of visual thresholds frequently involve large numbers of trials under a range of stimulus conditions, and data analysis which defines threshold as a point on a psychometric function. The slope of the psychometric function is commonly interpreted as reflecting stimulus-related, noise, due to variability in the stimulus and in the responses of the visual system to it. However, for inexperienced observers it is also necessary to consider the effects of extraneous noise, such as lapses in attention or cooperation (McKee, Klein & Teller, 1985; Teller, Mar & Preston, 1986; Klein & Manny, 1989). Stimulus-related noise affects the slope of the psychometric function without altering the upper asymptote, while extraneous noise can reduce the upper asymptote of the psychometric function below 100% correct. When extraneous noise causes the upper asymptote to be less than 100%, standard probit analysis (using a cumulative normal distribution from 50% to 100% correct) yields a shallow slope and considerable uncertainty in the threshold estimate. In the present study, we evaluated the effects of extraneous noise on analysis of data from inexperienced observers by analyzing two large sets of preferential-looking acuity data for normal infants and toddlers (data from Birch, 1985 and Birch & Hale, 1988).
Grating Acuity in Infants: Prototype vs Teller Acuity Cards
Authors: Dobson Velma , Luna Beatriz
Published: February 2023

The acuity card procedure1 is a modified version of the forced-choice preferential looking procedure (FPL)2 that has been used for the past fifteen years to measure grating acuity in individual infants in laboratory settings. In the FPL procedure, the observer's task is to watch the infant through a small peephole and to judge, based on the infant's eye and head movements, whether a black-and-white grating is located to the right or to the left of the peephole. After numerous presentations of at least four spatial frequencies of gratings, acuity is estimated as the (interpolated) spatial frequency that produced a score of 75 percent correct by the observer.
Effects of Gestational Age at Birth and Diet on Visual Acuity Development
Authors: Birch Eileen E. , Birch David G. , Uauy Ricardo
Published: February 2023

The normal course of acuity development for healthy fullterm infants has been well documented using both forced-choice preferential-looking (FPL) and visually evoked potential (VEP) procedures. This normal course of acuity development has also been shown to be vulnerable to the effects of abnormal visual experience during early development. Whether preterm birth, and attendant extreme immaturity of the visual system, renders infants more susceptible to the effects of visual experience is a question which remains unanswered. One approach to this issue has been to examine the impact of preterm visual experience on the rate of acuity development. A more rapid rate of acuity development for preterm infants than for fullterm infants would provide evidence for the influence of visual experience on the developing preterm visual system. Most FPL and VEP acuity data suggest that the rate of visual development for preterm and fullterm infants is equivalent when they are compared on the basis of postconceptual age; i.e., visual experience does not accelerate development in preterm infants (Baraldi et al., 1981; Birch and Spencer, 1989; Dobson, 1980, 1983; Fantz, 1975; Morante et al., 1982; vanHof-vanDuin and Mohn, 1984, 1985). However, there are also several reports, including both FPL and VEP studies, which are consistent with accelerated visual development in preterm infants, including FPL acuity (Mohn and vanHof-vanDuin, 1986), sweep VEP acuity (Norcia et al., 1985), and VEP latency (Sokol and Jones, 1978).
Visual Field Damage in Normal- and High-Tension Glaucoma
Authors: Chauhan Balwantray C. , Drance Stephen M. , Douglas Gordon R. , Johnson Chris A.
Published: February 2023

Optic disc and visual field damage in open angle glaucoma occurs under a wide range of intraocular pressure (IOP). The existence of different types of disc and field damage would suggest that factors other than IOP are responsible for the production of glaucoma.
Isolation of Receptor Photocurrent Response in the Gross Electroretinogram
Authors: Breton Michael E. , Montzka Dan
Published: February 2023

Much evidence links the a-wave feature of the gross electroretinogram (ERG) to receptor function and it has been well accepted since the work of Penn and Hagins in 1969 that the a-wave is generated by the summated photocurrents of the individual photoreceptors. However, up to the present, it has not been possible to separate the ERG waveform into components such that the component attributed to receptoral activity (a-wave) exhibits the parametric behavior known to occur for the photocurrent of isolated rod photoreceptors in response to very brief light flashes. In the analysis that follows, we present evidence in support of a component schema of a-wave and b-wave representation within the gross ERG waveform that identifies the features of an a-wave component in essential agreement with the major known parametric features of receptor photocurrent response. We also identify several important b-wave features not previously described.
Non-linear Processes In The Pupillary System
Authors: Howarth P.A. , Bailey I.L. , Berman S.M. , Heron G. , Greenhouse D.S.
Published: February 2023

The early stages of the visual and pupillary systems are thought to share common pathways. Observation of pupillary behaviour is therefore potentially a convenient, non-invasive, way to assess objectively those parts of the visual system which are shared. The pupil is readily visible, its size is easily recorded by (infra-red) photography and it is easily stimulated using everyday equipment.
Temporal impulse response from flicker sensitivity: application to Retinitis Pigmentosa patients
Authors: Dagnelie Gislin
Published: February 2023

Ever since De Lange (1952) introduced the application of linear systems theory to the study of properties of the human visual system, attempts have been made to convert flicker sensitivity data from the temporal frequency domain to the time domain. Such a transformation would allow a direct comparison between threshold data obtained with small flickering lights and threshold data obtained with brief light pulses. Indirectly it would allow comparison with results obtained using other techniques in the time domain, such as step stimuli (Rashbass 1970) and double pulse perturbation techniques (Roufs and Blommaert 1981). Time domain methods all involve the risk of changing the state of adaptation of the visual system; measurement of flicker sensitivity presents a constant average illumination to the retina, and thus a constant adaptation level.
In-Vivo Characterization of Intrinsic Fundus Fluorescence
Authors: Delori François C. , Fitch Karlotta A. , Gorrand Jean-Marie
Published: February 2023

Studies with vitreous fluorophotometry and fluorescein angiography have shown that ocular tissues exhibit intrinsic fluorescence properties. The fluorescence characteristics of the crystalline lens have been extensively studied. Little is known, however, about the origin of the weak fluorescence detected from the fundus and about the relative contribution of various fluorophores to that fluorescence. Different fluorophores that may have important diagnostic significance can be identified in the fundus layers. Lipofuscin accumulates with age in the human RPE and it has been hypothesized that this pigment plays a role in the pathogenesis of age-related macular degeneration [1-3]. FAD is a mitochondrial component of the respiratory enzyme chain [4]. The oxygenation-dependent fluorescence characteristics of this pigment could serve as a basis for measurements of the oxidative state of the retina.
Optimal Strategy in Using the Blue Field Simulation Technique for the Measurement of Macular Blood Flow
Authors: Petrig B.L. , Riva C.E.
Published: February 2023

The blue field entoptic phenomenon allows the observation of one’s own white blood cells passing through macular capillaries. Under optimal conditions of uniform retinal illumination with blue light (λ = 430 nm) many tiny corpuscles are seen randomly moving in all directions throughout the visual field. They recurrently procede along the same, albeit invisible, curved pathways prescribed by the inner retinal capillary loops. They feature a bright “head” and a dark “tail” and move in rhythmic accelerations synchronous with the heart cycle.
Optical Discontinuity Between Central and Peripheral Corneal Optics Following Radial Keratotomy
Authors: Applegate Raymond A. , Harvey Jana L. , Cottingham Andrew J. , Sharp Richard P. , Yee Richard W.
Published: February 2023

Last year our group reported preliminary results using the Howland and Howland subjective aberroscope that indicated the higher order monochromatic wave aberrations of radial keratotomy (RK) eyes were increased compared to similar nonsurgical eyes or the same eye prior to surgery.1 Additional data collection has revealed that the peripheral corneal surface is often irregular enough (27 eyes out of 34 eyes, 19 subjects) to prevent aberroscopic measurements adequate for analysis (see Figure 1).2 Along the same line, photokeratometric data on RK eyes document that, while the central corneal area radius increases (the cornea flattens and its power decreases) as desired, the peripheral cornea (surgical area) remains the same or steepens3. Both of these effects are consistent with the report that disability glare effects increase faster in the RK eye than in the normal eye with normal or drug induced pupil dilation.4 These three findings suggest that the difference between central and peripheral comeal optics following RK surgery is marked and may cause other significant visual function losses including a loss in acuity.
Bisection Accuracy and Precision in Patients with Retinitis Pigmentosa
Authors: Turano Kathleen
Published: February 2023

Retinitis pigmentosa (RP) is a pigmentary retinal degeneration that is typically characterized by profound nightblindness and progressive visual field loss. Visual field loss typically begins in the midperiphery as a ring scotoma and spreads both centrally and to the far periphery, resulting in severely contracted fields that often are characterized as "tunnel vision". Visual acuity typically remains 20/40 or better until the most advanced stages of the disease. Although RP has been characterized clinically, little is known about the spatial sense of the RP eye. For example, how accurate and precise are spatial position judgments when the visual targets are within the remaining parts of the patient’s visual field?
Development of a Noninvasive Video-Based Method of Measuring Transmission Properties of the Human Lens
Authors: Shu Huixia , Howard Dwight L. , Johnson Chris A.
Published: February 2023

The transmission properties of the ocular media are important for various aspects of vision research. Many age-related changes in visual function are in part due to the alteration in transmission properties of the ocular media as a consequence of the normal aging process (e.g. Weale, 1963; Werner and Wooten, 1980). In particular, there is a greater preretinal transmission loss for short wavelength light than for middle or long wavelengths. Recent investigations have also shown that certain eye diseases produce a selective loss of sensitivity to short wavelengths as an early manifestation of visual dysfunction (Adams, 1982; Applegate et. al., 1987; Heron et. al., 1988; Johnson et. al., 1989). It is therefore necessary to distinguish the amount of short wavelength sensitivity loss that is due to the ocular media from the portion that is due to early pathologic neural changes.
Lens "Yellowing" In Young, Type I Diabetics Occurs At A Similar Rate To Normals Over The Age of 60
Authors: Lutze Margaret , Bresnick George H.
Published: February 2023

It is well-established that the transmission of short-wavelength light through the lens is reduced and the lens appears to "yellow" with age. The rate of this lens "yellowing" has been quantified (Pokorny, Smith and Lutze, 1987). The lens "yellows" at a relatively slow rate until the age of 60 years after which lens "yellowing" is accelerated. Here we present evidence that the lenses of young, Type I diabetics "yellow" at a similar rate to older normal controls over the age of 60 yr. We also discuss a possible molecular explanation for accelerated "yellowing" in both populations.
The Relations between Contrast Threshold, Lens Back Scatter, and Disability Glare
Authors: Yager Dean , Hage Taryn , Yuan Rumei , Mathews Steven , Katz Milton
Published: February 2023

"Disability Glare" is a term which is used to specify a number of different deficits in visual function which result from the presence of a light source in the visual field that is some distance from the visual task under investigation, such as detection of a spot of light or discrimination between two or more objects. In most instances, the "glare" effect can be attributed entirely to a veiling luminance produced by intra-ocular light scatter, and it is not the result of neural lateral interaction effects.
Practice Selectively Improves Pattern Discrimination in Glaucoma
Authors: Drum Bruce , Quigley Harry , Roros James
Published: February 2023

For the past several years, we have been working to develop a new visual field testing technique, called Pattern Discrimination Perimetry, for which the patient is asked to detect a nonrandom pattern of dots embedded in a large surrounding field of random dots. The overall densities of the dots in the target and surround fields are equal, so the patient cannot use luminance cues to detect the target. The features that distinguish the target pattern from the surround can be either the spatial arrangement of dots, the way the dots change in time, or a combination of both. In general, the visibility of the target depends on the degree of nonrandomness, orcoherence, of the target dots. To measure the patient's sensitivity to a pattern, we reduce its coherence by randomizing just enough of the target dots to make the pattern undetectable.
PC-Based Hyperacuity Tests
Authors: Aziz Seerat , Lakshminarayanan V. , Enoch J.M.
Published: February 2023

Hyperacuity is described as the ability to perceive a difference in relative spatial localization to the order of seconds of arc (Westheimer 1979). The various hyperacuity tasks include vernier acuity (line vernier, two-dot vernier), stereoacuity and orientation discrimination. It has been shown that hyperacuity is resistant to optical degradation of the retinal image (Enoch et al. 1983 and Williams et al. 1984), therefore, vernier judgements possess potential clinical importance as a test of visual function in patients with opaque media. A recent review of clinical use of hyperacuity is given by Enoch et al. (1985). Further studies on psychophysical hyperacuity tests, the modified vernier gap test and a bisection task test to detect and quantify metamorphopsia are discussed in this paper.
An evaluation of the ERG b-wave as a measure of inner nuclear layer activity: Implications for Naka-Rushton fits
Authors: Hood Donald C. , Birch David G.
Published: February 2023

The b-wave of the ERG has been used as a measure of the activity of the inner nuclear layer. Fulton and Rushton1 recorded human ERGs elicited by flashes of different intensities and fitted their data with the function where R is the trough-to-peak amplitude of the b-wave, Rm is the maximum amplitude, I is the flash intensity, and K is the semisaturation intensity. They observed that light adaptation changed the values of K and Rm and associated these changes with modification in "the b-wave generating mechanism". Arden et al2 extended this analysis to retinal disease by measuring response-intensity functions in patients and relating changes in K and Rm to the action of a disease at the receptors and/or "the b-wave generating mechanism". Since this study, hundreds of response-intensity functions have been collected in the clinic and the parameters K and Rm estimated.3−9 The solid curves in Fig. 1A show three ERG responses from a typical response-intensity series.7 The filled circles in Fig. 1B show the trough-to-peak b-wave amplitudes for the complete data set. The solid curve in Fig. 1B is the best fit of eq. 1 to the b-wave amplitudes.
Layer-By-Layer Analysis of Macular Diseases with Objectively Measured Visual Functions
Authors: Miyake Yozo
Published: February 2023

In macular diseases, identification of impaired retinal layer is of value in diagnosis and pathogenetic analysis. We introduce two methods, with which layer- by-layer visual functions of the macula can be evaluated objectively and quantitatively.
Specificity of Retinal Function Deficits in Usher’s Syndrome
Authors: Tyler Christopher W.
Published: February 2023

Sensitivity to sinusoidal temporal modulation (flicker sensitivity) for a uniform stimulus field is proving to be a useful technique for application to ophthalmological diagnosis. Flicker sensitivity has been shown in a variety of diseases to provide earlier detection than previously available tests;1,2 to measure a reversible component of the visual susceptibility to disease;3 to provide differential diagnosis among conditions which are similar according to other tests;4 to characterize the nature of the sensory deficit;4,5 and to provide information as to which retinal mechanisms are affected by the disease.4-6
Stimulus Duration and Visual Acuity in Retinitis Pigmentosa
Authors: Alexander Kenneth R. , Derlacki Deborah J. , Fishman Gerald A. , Szlyk Janet P.
Published: February 2023

Patients with retinitis pigmentosa (RP) not infrequently exhibit reductions in foveal visual acuity in addition to night blindness and peripheral visual field restrictions. Measurement of visual acuity in RP subjects has typically been made with an extended duration of target presentation. Since there is evidence of abnormal temporal processing in some RP subjects (e.g., Tyler et al., 1984; Dagnelie and Massof, 1990), it is possible that such long-duration viewing of acuity targets underestimates the degree of acuity loss under conditions of briefer target duration. To address this issue, we have examined the temporal properties of foveal vision in RP subjects using Sloan letter identification. First, we measured log MAR (minimum angle of resolution) as a function of stimulus duration to determine whether RP subjects demonstrate a greater degree of acuity loss at short durations. Second, we measured contrast thresholds as a function of stimulus duration at a fixed letter size to determine whether temporal summation for letter identification is abnormal.
Retinal Locus for Identification in Observers with Vision Loss
Authors: Schuchard Ronald A.
Published: February 2023

Many people with vision loss have difficulty locating and identifying familiar objects. There is very little known about the retinal aspects of visual search with vision loss. While eye-trackers have provided information about eye-movements in visual search, only instruments that allow the assessment of visual stimuli position directly on the retina provide information about the retinal aspects of visual search. This in turn documents the relationship between visual search performance and retinal pathology in macular disease. Characteristics of the retinal locus for identification and characteristics of the movement of the retinal locus for identification (saccades) were studied to ascertain their relationship to decreased efficiency in visual search for observers with vision loss.
Improving the Reliability of the Pelli-Robson Contrast Sensitivity Test
Authors: Bullimore Mark A. , Elliot David B , Bailey Ian L.
Published: February 2023

The clinical applications of contrast sensitivity testing have been discussed in numerous reports, and a number of printed contrast sensitivity tests are commercially available. Some of these tests use letters as targets rather than sine or square wave gratings (Regan and Neima, 1983; Pelli et al., 1988). Letter contrast sensitivity charts have the advantage of being quick to administer and the nature of the task is familiar to both the patient and the practitioner. The letter identification task has the advantage of being a multiple-alternative forced-choice procedure that limits patient criterion effects (Vaegen and Halliday, 1983). The Pelli-Robson chart (Pelli et al., 1988) consists of sixteen triplets of letters, with each letter subtending 3 degrees at the recommended viewing distance of 1 meter. Within each triplet the letters have the same contrast and the contrast in each successive triplet decreases by a factor of 0.15 log units (√2). Pelli et al. recommend scoring contrast sensitivity as the lowest contrast level at which at least two of the triplet are identified correctly.
The Critical Spatial Frequency for Face Recognition
Authors: Peli Eli , Young George M. , Goldstein Robert B. , Trempe Clement L.
Published: February 2023

The existence of a critical spatial frequency range for face recognition has been debated widely in the literature in the last decade. Ginsburg (1980) argued that the low spatial frequencies (1-4 cycles/face width) were sufficient for recognition. On the other hand, Fiorentini et al (1983) found that recognition of face images limited to spatial frequencies below 5 cycles/face width was worse than recognition of images filtered to contain only higher frequencies.
Analysis of Visual Evoked Potential Using Generalized Order Statistic Filters
Authors: Longbotham Harold G. , Glickman Randolph D.
Published: February 2023

Electrophysiology provides a means for obtaining an objective measure of neural function, as well as an indicator of nervous system pathology. In the case of the visual system, noninvasive electrophysiology commonly utilizes recording the potentials evoked by visual stimuli from various points along the optic tract. Although the flash electroretinogram may be well over 150 microvolts in amplitude, the steady-state visual evoked potential (ssVEP), elicited from the visual cortex by counterphased, patterned stimuli, is usually much lower--on the order of 1 to 10 microvolts. In the clinic, the response recorded from patients may be of even lower amplitude due to the underlying disease process. In addition, the pathology may change the nature of the ambient noise, as well as making the patient less amenable to the recording process. All of these factors interfere with the use of the ssVEP in electrodiagnosis. Clearly, techniques which improve the analysis of evoked potential data will be welcomed by the clinical electrophysiologist. We have found that the generalized order statistic (GOS) filters can be used to analyze ssVEP data, reducing the length of recording time required to acquire the signal, and improving the signal to noise ratio by removing transient and impulsive noise from the biological data. The principles and practice for the use of generalized order statistic filters will be outlined below.
Noninvasive Assessment of the Instantaneous Net Pulsatile Component of Ocular Blood Flow
Authors: Silver David M. , Farrell Richard A. , Langham Maurice E. , Schilder Peter
Published: February 2023

The instrument used to record the intraocular pressure pulse is the computerized Langham pneumatic tonometer (Ref. 1). It consists of a noninvasive small probe that measures the intraocular pressure and a computer that processes the data. Thus the pressure can be followed along each pulse and is seen to follow the arterial pulse cycle. The intraocular pressure measurements can be made with intervals on the order of 10 to 30 milliseconds; each specific measurement is performed over several microseconds.
Pupillary Responses to Stimulus Structure and Colour - Possible mechanisms
Authors: Barbur John L
Published: February 2023

In addition to the pupil light reflex response (PLR), recent investigations have shown that systematic pupillary changes can be induced by changing certain stimulus attributes such as spatial structure and colour which are normally associated with central stages of visual processing1. For example, systematic pupillary responses have been demonstrated as a function of check size in experiments with checker-board patterns2,3, temporal modulation frequency with uniform fields4,5 and as a function of stimulus wavelength6 or the temporal exchange of monochromatic lights7,8.
Spectral Topography of the Optic Disc
Authors: Baumbach P. , Rassow B.
Published: February 2023

The topography of the nerve fiber layer of the optic disc plays an important role in the diagnosis of glaucoma. In the past two decades, different optical methods have been used for in vivo topographic measurements [3, 5, 6].
Glare: Clinical Assessment and Applications
Authors: Bailey Ian L.
Published: February 2023

We will discuss the clinical assessment of disability glare, discomfort glare, and glare recovery and show their relevance to diagnostic and treatment decisions.
Pupillary Studies of The Retinal "off" Response
Authors: Kardon Randy H. , Mirsky Roman
Published: February 2023

It has been known for many years that not all electrical discharges arising from the retina are due to a light stimulus. Some occur as a result of the light being turned off. The "off" response of the retina was recorded in early electroretinographic studies (1-3) when the light stimulus used was not of such short duration as used in present studies with the xenon flash. The "off response is also a well recognized spike discharge from a certain population of retinal ganglion cells that only seem to respond when a light stimulus is terminated (4,5). Similar recordings have been characterized from the lateral geniculate nucleus (6), the pretectal pupillocontrictor centers (7), and the ciliary nerves (8,9).
Nature of the Transient Pupillary Constriction To Light
Authors: Young Rockefeller SL , Han Bae-Choel , Wu Ping-yuan
Published: February 2023

It is well known that nerve fibers from the optic tract (as well as from several other pathways) project to the pretectum and drive the pupillomotor nuclei. But it has been less clear as to how or to what extent the pupillary light responses can provide information about visual function. A study by Leventhal, Rodieck, and Dreher (1981), however, may furnish an important clue. The investigators reported that the fibers forming the retinopretectal pathway in primates come from morphological A-, C-, and E- types of retinal ganglion cells. B-cells, the type which projects to the parvocellular layers of the lateral geniculate nucleus (LGN), do not terminate in the pretectum. A-cells, the type which also projects to the magnocellular layers of the LGN, do. (Hereafter, we use the terms M- and P-pathway in accordance with Shapley (1990) when speaking of the A- and B-cells, respectively, or die neural signals that originate from the two).
Measurement of Local Refractive Error
Authors: Webb Robert H. , Penney C. Murray , Thompson Keith P.
Published: February 2023

We have measured refractive error through a succession of small regions of the cornea. In these initial measurements approximately twenty regions of 1 mm diameter are selected for each measured eye. For experimental convenience, the regions are chosen along vertical horizontal and 45 degree oblique meridia through a central point near the comeal apex. Refractive error at each locus is determined by a variant of the Scheiner principle.
Predicting Progression to Glaucomatous Field Loss with the Temporal Visuogram
Authors: Tyler Christopher W. , Stamper Robert L. , Hawker Nina
Published: February 2023

Sensitivity to sinusoidal temporal modulation (flicker sensitivity) for a uniform stimulus field is proving to be a useful technique for application to ophthalmological diagnosis. Flicker sensitivity has been shown in a variety of diseases to provide earlier detection than previously available tests;1,2 to measure a reversible component of the visual susceptibility to disease;3 to provide differential diagnosis among conditions which are similar according to other tests;4 to characterize the nature of the sensory deficit;4,5 and to provide information as to which retinal mechanisms are affected by the disease.4-6
Effect of Increased Intraocular Pressure on Optic Nerve Blood Flow and its Response to Diffuse Luminance Flicker
Authors: Cranstoun S.D. , Riva C.E.
Published: February 2023

The pathogenesis of optic nerve (ON) atrophy and visual field defects in glaucoma is a subject of controversy. Mechanical and vascular factors have been claimed to cause damage to the optic nerve head. The mechanical theory, including impaired axonal flow, can account for nerve fiber defects through raised intraocular pressure (IOP).1,2,3,4 Support for the vascular theory stems from histological and fluorescein angiographic studies in advanced glaucoma,5,6 but there is little evidence for impaired microcirculation in the ON in the early stage of the disease, in part due to the lack of an objective, precise and noninvasive technique for measuring ON circulation in humans. The development of such a technique is highly desirable to help substantiate or dismiss the vasogenic theory. If neuronal degenerations are associated with vascular changes, the detection of subtle changes in ON blood flow may allow early diagnosis of nerve damage. This may be important since it appears that 20-30% loss of fibers can occur without being detected by current methods of examination.7
Detection and Discrimination of Mirror-Image Letter Pairs in Central and Peripheral Vision
Authors: Higgins Kent E. , Arditi Aries , Knoblauch Kenneth
Published: February 2023

Loss of central visual field function seriously disrupts reading performance (Legge et al., 1985; Cummings et al., 1985). Moreover, after magnification to compensate for the acuity loss and even after, prolonged training, reading speed in individuals with such losses rarely approaches that of normally- sighted individuals using central vision. Although it might be argued that subtle peripheral field losses that are undetected in clinical perimetry might limit reading performance, it seems unlikely that such an explanation would, by itself, be sufficient. For example, Turano and Rubin (1988) have noted deficient reading performance in the peripheral retina of those with normal function in both central and peripheral retina. Hence it seems more likely that reading deficits with central visual losses are due to differences in visual capabilities between central and peripheral visual field.
Assessment of binocular integration in amblyopia using a motion stimulus
Authors: Carney Thom , Schor Clifton , Steinman Scott , Wilson Nance
Published: February 2023

Along with reduced acuity, amblyopia is usually associated with a stereo-acuity deficit. Indeed, stereo testing has been recommended as an effective means of screening for amblyopia (Kani, 1978, Reinecke and Simons, 1974). The absence of stereo depth perception however does not preclude other forms of binocular interaction. Anderson, Mitchell and Timney (1980) have demonstrated interocular transfer of contrast threshold elevation in amblyopes. The contrast elevation is normal for spatial frequencies where contrast sensitivity was equal in the two eyes and was virtually absent at other frequencies (Selby and Woodhouse, 1981). Levi et. al. (1979) report interocular threshold elevations which are tuned for size and orientation in stereoblind amblyopic observers. Another example of binocular integration has been reported using flickering stimuli which lack spatial structure (Baitch and Srebro, 1990; Baitch and Levi, 1989). With different frequencies in each eye, temporal beat frequencies are perceived in observers with binocular function. However, these measures have limited utility in a clinical setting where the time for training and testing is restricted. Our goal in this project is to evaluate a cyclopean motion test of binocular integration for use in a clinical setting and assess its sensitivity to residual binocular function in amblyopes. Binocular integration is required for the perception of continuous motion with this cyclopean motion stimulus, neither eye's image alone contains a direction cue (Carney, et al, 1987; Shadlen and Carney, 1986). Horizontal disparity does not provide a cue either, therefore the subject does not necessarily need stereopsis to perceive the motion. The stimuli can be briefly presented and the task is simply to indicate perceived direction of motion, up or down. Moreover, the stimuli can be used to evaluate binocular integration at specific spatial frequencies and have the advantage that moderate horizontal misalignment of the eyes can be tolerated. The cyclopean motion stimulus might provide information concerning binocular integration for stimuli with spatial structure beyond that obtained with standard clinical tests of stereo-acuity.
Use of a Neural Network to Classify Electroretinograms in Central Retinal Vein Occlusion
Authors: Severns Matthew L. , Johnson Mary A. , Khadjenouri Dariush
Published: February 2023

The electroretinogram (ERG) has been shown to be an excellent predictor of outcome in central retinal vein occlusion (CRVO), distinguishing with high sensitivity and specificity those eyes that will develop neovascularization of the iris (NVI) from those that will not (no-NVI).1-6 Although few of these studies agree on the parameter that best separates NVI eyes from no-NVI eyes, most of the parameters investigated in these studies (R
max
and log K from Naka-Rushton analysis, 30 Hz flicker implicit time and amplitude, b-wave to a-wave amplitude ratio, b-wave implicit time) perform well in separating the two groups. Examination of the relationships between these parameters show that most of them are correlated.* This leads to the question "Are all of these parameters measuring the same underlying phenomenon (with varying degrees of noise added), or are some of them measuring different things?"
Visual Acuity and Pupil Size in Maxwellian and Free View Systems With and Without Refractive Error
Authors: Applegate Raymond A. , Bradley Arthur , Thibos Larry N.
Published: February 2023

Visual acuity is an integral part of a standard eye exam. Its value lies in its acute sensitivity to retinal image quality (Hirsch 1945; Peters 1961). Typically, 0.25 diopters of refractive error can produce a reliable change in acuity (Perrigin, Perrigin et al. 1982). However, the effects of refractive error vary with pupil size (Atchison, Smith et al. 1979).
Increment threshold spectral sensitivity functions on coloured backgrounds: Implications for colour perimetry
Authors: Hudson Chris , Wild John M.
Published: February 2023

The recent interest in blue-on-yellow perimetry can be attributed to
the increased sensitivity of the technique in detecting early
glaucomatous visual field loss when compared to standard white-onwhite
perimetry1. The objective of blue-on-yellow perimetry is
the isolation of a blue cone response (SWS). An intense yellow
background to saturate the green (MWS) and red (LWS) cones, and a blue
stimulus to preferentially stimulate the blue cones, are
employed2. There is evidence to suggest that the
parvocellular ganglion cells conveying signals from the blue cones are
of a larger diameter than other parvocellular cells3 and
are preferentially damaged in glaucoma4.
Spatial Position Perception across a Scotoma
Authors: Schuchard Ronald A.
Published: February 2023

Recently there has been increased interest in how the visual system compensates for gaps in perception due to scotomas (e.g., Ramachandran, 1992). However, it has been difficult to control the placement of the stimuli so that the stimuli are always at the desired retinal location relative to the scotoma. Lettvin (as cited in Ramachandran, 1992) reports that vertically misaligned lines across the physiological blind spot are perceived as being in-alignment. But, Lettvin also reported that horizontal misaligned lines are not perceived as being in-alignment. This study measures the horizontal and vertical alignment threshold of lines across a scotoma by using a scanning laser ophthalmoscope to place the lines at specific retinal locations relative to the scotoma. In addition, this study measures the horizontal and vertical bias in the perceived in-alignment lines to determine the amount of distortion in spatial position across a scotoma. This spatial distortion is often referred to as metamorphopsia, a perception in which objects appear distorted and/or larger or smaller than their actual size. The measurement of metamorphopsia using a vernier acuity task was proposed by Enoch et al. (Enoch, Baraldi et al., 1988), although the technique has been developed for subjects with ocular media opacities and not subjects with scotomas (Lakshminarayanan, Aziz et al., 1992). This study will determine whether subjects with macular scotomas can have spatial position perception that includes a distortion in the bias and/or a higher threshold for in-alignment mapping from object space to perception space.
Variability and Sensitivity of Short-Wavelength Color Visual Fields in Normal and Glaucoma Eyes
Authors: Sample Pamela A. , Cook James N. , Weinreb Robert N.
Published: February 2023

It has been shown that color visual fields 1) differentiate between normal and glaucomatous eyes; 1-4 2) show deficits in many suspect eyes when standard fields remain normal; 3 3) indicate more extensive damage across the retina than evidenced by standard visual fields; 4) show progressive loss sooner than standard fields in many eyes with primary open angle glaucoma;5 and 5) can identify early functional loss in suspect eyes at greatest risk for glaucoma. 6 These results suggest that color visual field testing may be a useful clinical test for assessing functional damage in ocular hypertension and primary open angle glaucoma. However, its clinical utility depends in large part on its ability to reliably detect glaucoma in a patient population.
Foveal Flicker Sensitivity Abnormalities Associated with Visual Field Defects in the Elderly
Authors: Eisner Alvin , Samples John R. , Campbell Heidi M.K.
Published: February 2023

This study of visual function in the elderly evolved from previous studies mainly on the basis of one simple premise: namely, that detection of functional deficit due to glaucoma may be enhanced by testing the eye while it responds near the limit of its operating range. To achieve this state, we measured flicker sensitivity while the eye was in the process of adapting to somewhat extreme (but harmless) stimulus conditions.
Flicker Perimetry in Ocular Hypertensives: Evidence for High- and Low-Sensitivity Defects
Authors: Casson Evanne J. , Johnson Chris A.
Published: February 2023

Recently there has been an accumulation of evidence suggesting that flicker sensitivity can be abnormally high in some ocular hypertensives,1-3 as well as in some low-tension glaucoma patients.4,5 While little is known about the basis for these abnormalities, it has been suggested that they may be the result of abnormalities in the effective adaptation state of the retina.5 To further the understanding of these highsensitivity flicker abnormalities, we present data from a three-year study of Temporal Modulation Perimetry (TMP) in ocular hypertensives and glaucoma patients.
Photopic A-Wave of the Primate Electroretinogram Contains a Contribution from the Inner Retina
Authors: Bush Ronald A. , Sieving Paul A.
Published: February 2023

The electroretinogram (ERG) is a very valuable noninvasive tool in the diagnosis of retinal diseases and a sensitive measure of retinal function. Analysis of the various components provides important information about the functioning of different retinal neurons (reviews: Brown, 1968; Ikeda, 1987; Steinberg et al., 1991). The leading edge of the dark-adapted rod a-wave is known to be associated with rod photoreceptor activity (Granit, 1933, 1947; Brown, 1968; Penn and Hagins, 1969; Heynen and van Norren, 1985).
Early Focusing History Predicts Later Refractive State: A Longitudinal Photorefractive Study
Authors: Howland Howard C. , Waite Stephen , Peck Leilani
Published: February 2023

A fundamental question of the development of the focus of the eye concerns the interplay of inheritance and environment in determining whether the person will become normally sighted, nearsighted, or farsighted. A test for the strength of inheritable influences is to ask if the future refractive state of a subject can be predicted by the focusing behavior in infancy. That this is so was reported by Gwiazda and co-workers1 using dark retinoscopy who found that school age myopia was predicted by infant refractive state.
Contour Interaction with High and Low Contrast Charts
Authors: Bailey Ian L , Raasch Thomas W. , Koh Peter , Hetland Martin , Park Anthony
Published: February 2023

Visual acuity measurement is a critical tool in the clinical assessment of visual function and in the identification of changes affecting the visual system. Traditionally, visual acuity is measured with letter charts with black letters presented in high contrast against a white background. While authoritative bodiesl.2 have made various recommendations about test chart design and calibration of optotypes, there is not a universally accepted standard. It has become common in clinical research to use charts which follow the design principles of Bailey and Lovie3 which ensure that the task is essentially the same at all size levels so that size remains the only significant variable. This requires that the chart has rows of optotypes descending in size in constant ratio steps, there should be the same number of optotypes at each size level, the spacing between adjacent optotypes and successive rows should be proportional to optotype size, and optotypes should have approximately equal legibility and they should be combined so that each row forms a set with equal difficulty. Spacing ratios can have a significant effect on the visual acuity scores4 of normally sighted subjects and in patients with amblyopia or with macular disorders, visual acuity performance can become substantially reduced when the task becomes more crowded and congested.5
Effect of Light Intensity on Macular Blood Flow Parameters Measured by Blue Field Simulation
Authors: Petrig B.L. , Kamoun L. , Riva C.E.
Published: February 2023

The measurement of retinal macular blood flow is important in the determination of the vascular status, in the assessment of treatment efficacy and in the evaluation of the effect of experimental drugs on the circulation. The blue field simulation (BFS) technique1is an established method for the quantitative determination of the velocity and number of leukocytes flowing in the capillaries of the central region of the visual field.2
Foveal Ferry-Porter Data in RP Patients: Saturation at High Intensities
Authors: Dagnelie Gislin
Published: February 2023

Retinitis pigmentosa patients experience severe limitations in their ability to adapt to changing light levels. Not only is their adaptation rate slower than that in persons with normal vision (impairing them in indoor-outdoor transitions), but the dynamic range over which they can function comfortably appears to be limited. These symptoms appear to become more serious as the disease progresses, but the clinical impression gained from patients suggests that this factor is only of minor importance.
Abnormalities of the Fellow Eye in Acute Unilateral Optic Neuritis
Authors: Barrett Katz , Roy W. Beck , Mark J. Kupersmith , Patricia A. Cleary , Marilyn E. Schneck , Gunilla Haegerstrom-Portnoy
Published: February 2023

The pathogenesis of optic neuritis typically involves demyelination, whether or not clinically apparent multiple sclerosis is present. In adults, the overwhelming majority of acute attacks are symptomatic in one eye only. Abnormal visual function in asymptomatic fellow eyes has been reported, though testing has not generally been performed until after resolution of the acute attack,1,2,3,4,5 or only done in patients with clinically evident multiple sclerosis.6,7 Visual function in the fellow eye at the onset of acute unilateral garden variety optic neuritis has not been systematically evaluated. We have previously described the unaffected eyes in 11 patients with acute unilateral optic neuritis.8 Their evaluation revealed deficits on several parameters, despite normal high contrast and low contrast visual acuities. Pelli-Robson contrast sensitivity, S-cone increment thresholds, M-cone increment thresholds and color vision (assessed with the Adams desaturated D-15) were often reduced. Performance on the SKILL card, a low-contrast, low luminance acuity measure, was also abnormal in most of these eyes (73%). We therefore sought to prospectively determine the prevalence of abnormalities in the fellow eyes of the 448 patients enrolled into the Optic Neuritis Treatment Trial (ONTT), a multi-center study which investigated the value of corticosteroids as treatment for optic neuritis. All patients underwent extensive visual function testing in both the affected and unaffected (fellow) eyes.9,10 Data collected on those fellow eyes form the basis for this report.
Multistable and Time Sequencing Photorefractive Ring Resonators
Authors: Anderson Dana Z. , Benkert Claus , Hermanns Anno
Published: February 2023

In this presentation we discuss and demonstrate the performance of two novel multimode photorefractive systems. The first is a multimode resonator with “winner-takes-all” dynamics. The resonator has several (in our case five) stable steady state solutions in which one mode always oscillates while all the others are suppressed. The system makes a decision which of the modes it will support depending on the initial conditions. The state of the system can then be switched with an external light signal. A modification of the resonator results in a different all-optical system which is capable of recalling a stored sequence of oscillating modes. The dynamics of this sequential recall process is again completely controlled by photorefractive two beam coupling.
Parametric Instability of a Propagating Bichromatic Field in a Three-Level Medium
Authors: Khanin Ya. I. , Kocharovskaya O. , Mandel Paul
Published: February 2023

Recent papers were published [1-3] where the idea of amplification without population inversion associated with the interference of different transitions was proposed. In one paper [2] four-level atoms with two upper levels which are purely lifetime broadened and decay to an identical continuum were considered. Two other papers [1,3] were connected with three-level systems in the Λ configuration interacting with the same quasimonochromatic field at both optical transitions.
Amplification, Instability, and Chaos in Nonlinear Counterpropagating Waves
Authors: Law C. T. , Kaplan A. E.
Published: February 2023

We demonstrate that two linearly polarized counterpropagating waves in a Kerr nonlinear medium with linear dispersion can exhibit amplification and multi-mode temporal instability, which are attributed to the combined effect of nonlinear index grating and linear dispersion.
Statistical Inference Theory Using Finite and Noisy Data Sets
Authors: Sayers Chera L.
Published: February 2023

The statistical properties of the correlation integral and the correlation dimension are discussed in the context of finite and noise infected data sets. Stochastic processes are defined and discussed in the context of hypothesis testing and time series modeling. Applications of the presented statistical techniques are discussed within the general goal of increased accuracy of linear and nonlinear time series model specification.
Quantum Noise Reduction in Nondegenerate Four-wave Mixing above Threshold
Authors: Brambilla M. , Strini G. , Lugiato L. A. , Prati F.
Published: February 2023

It is well known that nondegenerate four-wave mixing is one of the main mechanisms to produce nonclassical states of the electromagnetic field. As a matter of fact, the squeezing effect was first observed in this configuration1. Recently, sub-shot noise character in the fluctuations in the difference of the intensities of the two signal beams has been experimentally detected2, in analogy with the well known case of nondegenerate parametric oscillators3.