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PubMed1996

[Static contrast sensitivity in idiopathic Parkinson disease].

During Parkinson's disease static contrast sensitivity (C.S.) abnormalities are linked to an impairment of the sensitive visual function. C.S. was tested in twelve parkinsonians and 12 controls without neurological and/or ophthalmological pathology, using a Colored Stripes Electronic Generator (GEPCO). Results for parkinsons showed a general deficiency over the spectrum of spatial frequencies, which was statistically significant and particularly pronounced for intermediate frequencies. This study was repeated for three patients: it showed threshold deterioration for two of them, correlated by evolution in the disease, and an improvement for the third patient after introduction of dopatherapy. C.S. is subjected to dopaminergic control. Among parkinsonians. C.S. deterioration may result in an operating failure of both the visual cortex and retina, and is improved by dopatherapy. The Static Gepco contrast sensitivity test is easy to reproduce and can be used easily to monitor the sensory visual defect in parkinsonian patients under treatment.

Aged↗
PubMed1996

Contrast sensitivity and other vision tests in the optic neuritis treatment trial.

PURPOSE: To determine the intercorrelation, prevalence of abnormality, and incremental detection value of vision tests in optic neuritis. METHODS: We calculated the linear correlation of paired vision tests and prevalence of abnormal test values from baseline and six-month measurements of Snellen visual acuity, Pelli-Robson contrast sensitivity, Humphrey Field Analyzer mean deviation, and Farnsworth-Munsell 100-hue color vision in 438 patients entered in the Optic Neuritis Treatment Trial from 1988 to 1991. The incremental detection value of nonvisual acuity tests was defined as their frequency of abnormality when visual acuity was 20/20 or better. RESULTS: All four vision-test results were highly intercorrelated at baseline and at six months. At baseline, contrast sensitivity had the highest prevalence of abnormality, but all vision tests were so often abnormal that differences were not clinically relevant. At six months, when visual recovery had occurred, contrast sensitivity was most often abnormal (2.2 X visual acuity; 1.8 X mean deviation; 1.5 X Farnsworth-Munsell 100-hue color vision test); when contrast sensitivity, mean deviation, or Farnsworth-Munsell 100-hue color vision was normal, visual acuity was 20/25 or better in 98% of patients. CONCLUSIONS: The high intercorrelation of four vision tests suggests that optic neuritis affects a broad range of visual functions. Among non-visual acuity tests, Pelli-Robson contrast sensitivity proved to be a particularly practical and sensitive indicator of visual dysfunction in optic neuritis.

Adolescent↗
PubMed1988

High visual contrast sensitivity in the young human infant.

The visual evoked potential (VEP) was used to estimate photopic contrast sensitivity of 10-week-old infants over a wide range of spatial frequencies including the acuity limit. Adult and infant VEP contrast sensitivity was compared for sinusoidal luminance gratings reversed in contrast at 6 Hz. Space-average luminance was 220 cd/m2. Grating contrast was swept from well below the measured thresholds to well above them in 10 sec trials. Contrast thresholds were defined as the zero voltage intercept of the initial rising portion of the VEP amplitude versus contrast function. The VEP contrast sensitivity of 10-week-old infants was close to that of the adults for spatial frequencies below about 1 cycle (c)/deg.

Adult↗
PubMed1984

Glare from outdoor high mast lighting: effects on visual acuity and contrast sensitivity in comparative studies of different floodlighting systems.

Glare effects on visual acuity and contrast sensitivity were studied at outdoor timber terminal work with conventional far-reaching floodlighting and with a new type of oblique floodlighting with an asymmetrical light distribution. The binocular work visual acuity of 19 volunteers was measured at 40, 55 and 80 per cent contrast and the contrast sensitivity of 14 volunteers at spatial frequencies of 0.5, 1, 2, 4, 8 and 16 cycles/degree. With the light source 15 degrees from the centre of the visual fields the visual acuity as well as the contrast sensitivity was consistently lower with the conventional type than the new type of floodlight . The results thus indicate that not only the vision of details is impaired by glare but also the contrast perception of sparse patterns. In standardized rating scales the timber terminal workers scored the difference in glare between the two floodlight systems as "great"--"very great".

Adult↗
PubMed1987

Pathology of the optic nerve and visual association areas. Information given by the flash and pattern visual evoked potential, and the temporal and spatial contrast sensitivity function.

Spatial and temporal contrast sensitivity functions (CSF) were compared with visual evoked potentials (VEP) in two groups of patients with pathology selectively affecting different parts of the visual pathway. These consisted of 10 patients with a selective delay of the pattern VEP due to demyelination of one optic nerve (unilateral optic neuritis) and 11 patients with a selective delay of the flash VEP due to pathology of the visual association areas (primary presenile dementia, or Alzheimer's disease). The results led to the following conclusions. Comparison of the VEP and CSF results indicated that VEP latency was more closely associated with the temporal CSF than the spatial CSF. Pathology of the visual association areas which selectively increased the latency of the flash P2 component also reduced sensitivity at low and medium temporal frequencies. In demyelination of the optic nerve, a highly significant correlation was found between the delay of the pattern reversal VEP and sensitivity at high temporal frequencies. Comparison of the results in these two types of pathology suggests that the pattern VEP and flash P1 component, the spatial CSF, and temporal CSF at high temporal frequencies are all processed in the geniculostriate pathway. The flash P2 component and temporal CSF at low and medium frequencies were affected differently from the other measures. The possibility that these processes are transmitted by nongeniculate pathways is discussed.

Adult↗
PubMed1983

Vision evaluation using contrast sensitivity functions.

The use of Contrast Sensitivity Functions (CSF's) in vision evaluation has been explored for several years. Although theoretically superior to Snellen acuity and similar measures, the use of CSF is not widespread. A review of some of the clinical conditions in which CSF's have been used is followed by a discussion of the problems involved in their measurement and interpretation.

Aging↗
PubMed1986

The effect of horizontal differential prism on the binocular contrast sensitivity function.

The photopic binocular contrast sensitivity function is measured using a two-way resolution choice sinusoidal-grating target with horizontal differential prism before the right eye of one subject (AHT). A significant drop in sensitivity occurred with 3 prism-dioptres base-out or 4 prism-dioptres base-in prism at an observation distance of 5.9 m, and with 2 prism-dioptres base-out or 8 prism-dioptres base-in at 50 cm. An equivalent effect was confirmed with three additional subjects at a test distance of 2 m. The relationship between these results, the passive position, and the fusional reserves is discussed and reference is made to the effect of vertical differential prism.

Form Perception↗
PubMed1979

Contrast sensitivity functions for clinical optometry.

Contrast sensitivity functions (CSF) provide a better measure of visual function than traditional acuity tests. The use of CSFs with cataract and contact lens patients as well as with patients suspected to have glaucoma or retrobulbar neuritis is discussed. Various methods for determining the CSF are discussed, with the conclusion that the newly developed Arden plates are best for use in clinical practice.

Central Nervous System Diseases↗
PubMed1986

Three clinical tests of the spatial contrast sensitivity function: a comparison.

The purpose of this study was to establish a practical basis of comparison among three clinical tests designed to measure an observer's spatial contrast sensitivity function (CSF): the AO contrast sensitivity test plates (Arden grating test), the Vistech VCTS 6500 chart, and the Nicolet CS-2000 contrast sensitivity testing system (Optronics system). Each test was administered under standard conditions to a randomly selected subset of 71 normal observers. Scores were converted to absolute contrast and spatial frequency units for comparison. Results were similar for all three tests at intermediate and high spatial frequencies, but at low spatial frequencies the Vistech and Optronics tests yielded significantly lower sensitivity scores than the AO plates. This discrepancy is probably due to area truncation.

Adult↗
PubMed2001

Contrast sensitivity at age 10 years in children who had threshold retinopathy of prematurity.

OBJECTIVE: To evaluate monocular contrast sensitivity (CS) at age 10 years in eyes that underwent cryotherapy and in control eyes of participants in the randomized trial of cryotherapy for retinopathy of prematurity (CRYO-ROP), and in a comparison group of 10-year-old low-birth-weight children who did not develop ROP in the neonatal period. METHODS: Eligible participants were the 255 survivors of the group of 291 infants with severe (threshold) ROP in 1 or both eyes who were enrolled in the randomized CRYO-ROP trial as neonates, as well as 104 children in the CRYO-ROP study who did not develop ROP. All had birth weights less than 1251 g. Contrast sensitivity was measured using Pelli-Robson charts at a test distance of 1 m with luminance at or higher than 64 candelas (cd)/m(2). Contrast sensitivity was estimated using the total number of letters identified. RESULTS: Unfavorable CS outcomes (<27 letters identified) were found in a greater proportion of control eyes (59.3%) than of treated eyes (39.7%) (P<.001). In patients with bilateral threshold ROP who had quantifiable CS in both eyes, CS results were similar in treated and control eyes, suggesting no detrimental effect of cryotherapy. In the "no ROP" group, 96.9% of eyes showed CS in the normal range, compared with 48.1% of treated eyes and 34.6% of control eyes. CONCLUSIONS: The results further confirm the beneficial effect of cryotherapy on visual function, and show no evidence of adverse effects of cryotherapy on CS. With or without cryotherapy, eyes with severe ROP showed substantially poorer CS than did eyes of preterm children who did not develop ROP.

Child↗
PubMed2004

Light therapy increases visual contrast sensitivity in seasonal affective disorder.

The purpose of this study was to investigate the effects of light therapy on visual contrast sensitivity in patients with seasonal affective disorder (n=10) and healthy control subjects (n=10). Static and dynamic visual contrast sensitivity was measured using a Venus system before and after 4 weeks of light therapy (10,000 lux, 30 min, 5 times a week). Light therapy increased static visual contrast sensitivity in the patients. We found no significant difference between the patients and controls either before or after light therapy. These results raise the possibility that light therapy induces retinal sensitization in seasonal affective disorder.

Adult↗
PubMed2005

Voltage-gated sodium channels improve contrast sensitivity of a retinal ganglion cell.

Voltage-gated channels in a retinal ganglion cell are necessary for spike generation. However, they also add noise to the graded potential and spike train of the ganglion cell, which may degrade its contrast sensitivity, and they may also amplify the graded potential signal. We studied the effect of blocking Na+ channels in a ganglion cell on its signal and noise amplitudes and its contrast sensitivity. A spot was flashed at 1-4 Hz over the receptive field center of a brisk transient ganglion cell in an intact mammalian retina maintained in vitro. We measured signal and noise amplitudes from its intracellularly recorded graded potential light response and measured its contrast detection thresholds with an "ideal observer." When Na+ channels in the ganglion cell were blocked with intracellular lidocaine N-ethyl bromide (QX-314), the signal-to-noise ratio (SNR) decreased (p < 0.05) at all tested contrasts (2-100%). Likewise, bath application of tetrodotoxin (TTX) reduced the SNR and contrast sensitivity but only at lower contrasts (< or = 50%), whereas at higher contrasts, it increased the SNR and sensitivity. The opposite effect of TTX at high contrasts suggested involvement of an inhibitory surround mechanism in the inner retina. To test this hypothesis, we blocked glycinergic and GABAergic inputs with strychnine and picrotoxin and found that TTX in this case had the same effect as QX-314: a reduction in the SNR at all contrasts. Noise analysis suggested that blocking Na+ channels with QX-314 or TTX attenuates the amplitude of quantal synaptic voltages. These results demonstrate that Na+ channels in a ganglion cell amplify the synaptic voltage, enhancing the SNR and contrast sensitivity.

Action Potentials↗
PubMed2005

Perceptual learning improves contrast sensitivity and visual acuity in adults with anisometropic amblyopia.

To evaluate the effects of perceptual learning on contrast-sensitivity function and visual acuity in adult observers with amblyopia, 23 anisometropic amblyopes with a mean age of 19.3 years were recruited and divided into three groups. Subjects in Group I were trained in grating detection in the amblyopic eye near pre-training cut-off spatial frequency. Group II received a training regimen of repeated contrast-sensitivity function measurements in the amblyopic eye. Group III received no training. We found that training substantially improved visual acuity and contrast-sensitivity functions in the amblyopic eyes of all the observers in Groups I and II, although no significant performance improvement was observed in Group III. For observers in Group I, performance improvements in the amblyopic eyes were broadly tuned in spatial frequency and generalized to the fellow eyes. The latter result was not found in Group II. In a few cases tested, improvements in visual acuity following training showed about 90% retention for at least 1 year. We concluded that the visual system of adult amblyopes might still retain substantial plasticity. Perceptual learning shows potential as a clinical tool for treating child and adult amblyopia.

Adolescent↗
PubMed1990

Spatiotemporal contrast sensitivity differs in normal aging and Parkinson's disease.

We measured contrast sensitivity for static and laterally drifting vertical gratings in 12 young adults, 7 normal elderly adults, and 8 patients with Parkinson's disease (PD). We compared static and motion contrast sensitivity for spatial frequencies of 0.25, 1, and 4 cycles per degree (cpd), and temporal frequencies of 1, 3, and 9 Hz. Results show that normal aging leads to a reduction of motion sensitivity for the spatial frequency of 0.25 cpd. Compared with elderly controls, PD patients do not present specific abnormalities in this domain. However, for spatial frequencies of 1 and 4 cpd and temporal frequencies of 1 and 3 Hz, motion sensitivity is worse than static sensitivity in PD patients and not in elderly controls. These findings suggest a specific deficit of motion perception in PD, and possible dopaminergic involvement in the control of visuospatial behavior.

Adult↗
PubMed2003

Effect of methods of myopia correction on visual acuity, contrast sensitivity, and depth of focus.

PURPOSE: To psychophysically measure spherical and irregular aberrations in patients with various types of myopia correction. SETTING: Laboratory of Experimental Ophthalmology, University of Groningen, Groningen, The Netherlands. METHODS: Three groups of patients with low myopia correction (spectacles, soft contact lens, and Intacs) and 4 groups with high myopia correction (spectacles, rigid contact lens, Artisan claw lens, and laser in situ keratomileusis [LASIK]) had through-focus contrast sensitivity measurements to establish the myopic shift and depth of focus. From these 2 parameters, spherical and irregular aberrations were determined using theoretical eye models and geometric optics. Visual acuity, stray light, and predictability were also studied. RESULTS: There were no differences in best corrected visual acuity (BCVA) or best corrected contrast sensitivity between the low myopia groups. The Intacs group had a significantly larger depth of focus (P<.05). The results in the soft contact lens group were comparable to those in a human eye model with an average amount of spherical and irregular aberrations. The LASIK group had worse uncorrected visual acuity (UCVA) and best corrected contrast sensitivity than the spectacles, rigid contact lens, and Artisan claw lens groups (P<.05) due to the amount of spherical and irregular aberrations present after LASIK. The low and high myopia spectacles groups had average amounts of spherical and irregular aberrations. CONCLUSIONS: Neither surgical techniques nor contact lenses resulted in BCVA or best corrected contrast sensitivity that surpassed the values measured in the best corrected spectacles groups. The Artisan claw lens performed better than LASIK in UCVA, predictability, and best corrected contrast sensitivity.

Adult↗
PubMed1993

Modelling the dependence of contrast sensitivity on grating area and spatial frequency.

We modelled the human foveal visual system in a detection task as a simple image processor comprising (i) low-pass filtering due to the optical transfer function of the eye, (ii) high-pass filtering of neural origin, (iii) addition of internal neural noise, and (iv) detection by a local matched filter. Its detection efficiency for gratings was constant up to a critical area but then decreased with increasing area. To test the model we measured Michelson contrast sensitivity as a function of grating area at spatial frequencies of 0.125-32 c/deg for simple vertical and circular cosine gratings. In circular gratings luminance was sinusoidally modulated as a function of the radius of the grating field. In agreement with the model, contrast sensitivity at all spatial frequencies increased in proportion to the square-root of grating area at small areas. When grating area exceeded critical area, the increase saturated and contrast sensitivity became independent of area at large grating areas. Spatial integration thus obeyed Piper's law at small grating areas. The critical area of spatial integration, marking the cessation of Piper's law, was constant in solid degrees at low spatial frequencies but inversely proportional to spatial frequency squared at medium and high spatial frequencies. At low spatial frequencies the maximum contrast sensitivity obtainable by spatial integration increased in proportion to spatial frequency but at high spatial frequencies it decreased in proportion to the cube of the increasing spatial frequency. The increase was due to high-pass filtering of neural origin (lateral inhibition) and the decrease was mainly due to the optical transfer function of the eye. Our model explained 95% of the total variance of the contrast sensitivity data.

Computer Simulation↗
PubMed2002

Contrast sensitivity in pigeons: a comparison of behavioral and pattern ERG methods.

Contrast sensitivity (CS) is often used to assess spatial and temporal vision in animals. Conventional behavioral psychophysical techniques are both time and labor intensive, whereas measurement of CS functions by means of the pattern electroretinogram (PERG) is considerably more rapid and efficient. Are the two methods comparable, however? To answer this question, contrast-sensitivity functions were obtained using both the PERG and behavioral psychophysics in the same subjects, which were White Carneaux pigeons. The stimuli, in both methods, were phase-reversing, contrast-modulated sweeps of sinusoidal gratings. The PERG-CS functions were recorded via corneal electrodes and the behavioral data were collected using a modified staircase method that used moderate food deprivation and food reward. The results indicated that the PERG-CS functions had comparable bandwidth and peak spatial frequency to the behavioral CS functions. The PERG-CS functions, however, were lower on average than the behavioral curves by about 54%. The visual acuity of the two methods, as estimated from the high-frequency cutoff of the CS functions, differed by 37%. Both of these values are roughly consistent with the square root of 2 advantage of binocular viewing (behavioral method) over monocular viewing (PERG method). In addition, the peak spatial frequency showed a decrease of 0.125 c/deg with the PERG method and bandwidth was reduced by approximately 0.5 octave. These findings suggest that the PERG is an acceptable alternative to behavioral measurement of CS functions, especially in animal psychophysics, if one takes into account the underestimation of CS by the PERG method and the small changes in peak spatial frequency and bandwidth.

Animals↗
PubMed1985

Central and peripheral contrast sensitivity for static and dynamic sinusoidal gratings in glaucoma.

Contrast sensitivity testing in glaucoma patients was extended from central, static patterns to include peripheral areas and dynamic gratings. The results were compared with age-matched normals in visuograms, and sensitivity defects were correlated to the location of visual field defects. Tested spatial frequencies included 0.3, 0.5 1, 2 and 4 c/d. Definite sensitivity losses for all spatial frequencies were found for dynamic patterns in testing positions located 10 degrees eccentrically above and below fixation. For static patterns in the periphery sensitivity was reduced only for medium spatial frequencies. For central viewing, reduced sensitivity was found with dynamic medium spatial frequencies only. No centrally presented static gratings were of subnormal sensitivity. Dynamic patterns in the periphery were superior to other combinations regarding the capacity for indicating the presence of glaucomatous influence. Peripheral sensitivity losses also occurred when perimetric disturbances were located outside the area tested in the same hemi-field. Depressed sensitivity was observed even in hemifields with normal/near-normal perimetric fields. These findings might be indicative of an early glaucomatous impairment. It thus seems that testing peripheral dynamic contrast sensitivity might be a potentially valuable method for glaucoma screening.

Aged↗