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PubMed2004

Contrast sensitivity threshold measured by sweep-visual evoked potential in term and preterm infants at 3 and 10 months of age.

Although healthy preterm infants frequently seem to be more attentive to visual stimuli and to fix on them longer than full-term infants, no difference in visual acuity has been reported compared to term infants. We evaluated the contrast sensitivity (CS) function of term (N = 5) and healthy preterm (N = 11) infants at 3 and 10 months of life using sweep-visual evoked potentials. Two spatial frequencies were studied: low (0.2 cycles per degrees, cpd) and medium (4.0 cpd). The mean contrast sensitivity (expressed in percentage of contrast) of the preterm infants at 3 months was 55.4 for the low spatial frequency (0.2 cpd) and 43.4 for the medium spatial frequency (4.0 cpd). At 10 months the low spatial CS was 52.7 and the medium spatial CS was 9.9. The results for the term infants at 3 months were 55.1 for the low spatial frequency and 34.5 for the medium spatial frequency. At 10 months the equivalent values were 54.3 and 14.4, respectively. No difference was found using the Mann-Whitney rank sum T-test between term and preterm infants for the low frequency at 3 or 10 months or for the medium spatial frequency at 3 or 10 months. The development of CS for the medium spatial frequency was equally fast for term and preterm infants. As also observed for visual acuity, CS was equivalent among term and preterm infants, suggesting that visual experience does not modify the development of the primary visual pathway. An earlier development of synapses in higher cortical visual areas of preterm infants could explain the better use of visual information observed behaviorally in these infants.

Contrast Sensitivity↗

PubMed1986

[Study of spatial function using the contrast sensitivity function. Cases of presbyopic subjects fitted with progressive glasses].

The spatial properties of the global visual system were measured on the basis of the contrast sensitivity function, in three presbyopic observers. Shape alterations of the contrast sensitivity curves were found depending on the experimental conditions: foveal vision, in far, intermediary and near vision, along central, 13 degrees nasal and 13 degrees temporal meridians (according to three parallels and three meridians), peripheral vision, in far and near vision, at 13 degrees and 26 degrees retinal eccentricities using the central or nasal part of the lens. The central meridian was found to be the most efficient part of the progressive lenses. These results strengthen the observations reported by ophthalmologists and progressive lens wearers.

Accommodation, Ocular↗

PubMed1979

Measuring contrast sensitivity with gratings: A new simple technique for the early diagnosis of retinal and neurological disease.

The measurement of contrast sensitivity using gratings is a new clinical procedure which yields information about the functioning of the visual system. Previously, this type of information has not been readily obtainable in the clinical environment. This article includes the basic concepts of measuring contrast sensitivity with gratings and preliminary clinical results.

Evaluation Studies as Topic↗

PubMed1997

The development of chromatic and achromatic contrast sensitivity in infancy as tested with the sweep VEP.

Swept-contrast visual evoked potential (VEP) techniques were used to measure the development of contrast sensitivity functions (CSFs) for achromatic and red/green isoluminant chromatic gratings. Subjects were infants of 8, 14, 20 and 32 weeks of age, and adults. Stimuli were 20 deg, 0.3-4 cyc/deg sinusoidal gratings, counterphased at 6 Hz and modulated through white. Achromatic and chromatic CSFs for all ages could be fit simultaneously with a double exponential equation of a common, lowpass shape. Both achromatic and chromatic CSFs exhibited developmental shifts in both sensitivity and spatial scale. From 8 weeks to adulthood, sensitivity increased by 0.64 log units for achromatic gratings and by 0.91 log units for chromatic gratings, yielding an 0.27 log unit larger sensitivity change for chromatic than for achromatic stimuli. Spatial scale shifts were closely similar across achromatic and chromatic CSFs, and were consistent with the factor of about four predicted on the basis of changes in foveal receptor packing density and eye size. The question of uniform vs differential loss of sensitivity for chromatic vs achromatic stimuli at fixed spatial frequencies is discussed.

Adult↗

PubMed1992

Contrast sensitivity deficits in subjects with glaucoma-like discs using an oscilloscope-based method.

The central visual function of 20 subjects with glaucoma-like discs, normal intraocular pressures and normal visual fields and 20 age-matched normal subjects was assessed by measuring contrast sensitivity using an oscilloscope technique. The subjects with glaucoma-like discs exhibited a significant reduction in contrast sensitivity compared to the age-matched normal; these differences were greatest at spatial frequencies of 2 and 4 cdeg-1.

Aged↗

PubMedDate not supplied

Cognitive and sensorimotor functions in 6-year-old children in relation to lead and mercury levels: adjustment for intelligence and contrast sensitivity in computerized testing.

Within a larger environmental health screening program neurobehavioral measures were taken in 384 6-year-old children (mean age 74 months) in the cities of Leipzig, Gardelegen, and Duisburg. Lead concentrations in venous blood samples (PbB) and urinary mercury excretion in 24-h samples (HgU) were measured as markers of environmental exposure by electrothermal AAS. Dependent variables included two subtests from the WISC [vocabulary (V) and block design (BD)] as well as five tests from the NES2 [pattern comparison, pattern memory, tapping, simple reaction time, and the continuous performance test (CPT; child version)]. In addition, visual functions [visual acuity (TITMUS-test) and contrast sensitivity (FACT)] were tested as covariates. The overall average PbB (geometric mean) was 42.5 microg/l (upper 95% value = 89 microg/l). The overall average mercury excretion (HgU) was 0.16 microg/24 h. Whereas no significant or borderline associations between HgU and any of the target variables was found, significant negative associations were observed between PbB and verbal intelligence (WISC vocabulary but not WISC Block Design) and false-positive responses (false alarms), as well as false-negative responses (miss) in the CPT. Whereas parental education was the most important confounder for WISC performance, visual contrast sensitivity and computer familiarity also proved predictive for performance in several computer-based NES subtests. It is concluded that non-IQ measures, namely measures of sustained attention, are negatively affected in children with 95% of blood-lead levels below 90 microg/l, even after adjustment for intelligence and contrast sensitivity, whereas the causative role of lead in altering IQ functions remains somewhat equivocal, because important covariates could not be controlled for.

Child↗

PubMed1999

Are contrast sensitivity functions impaired in insulin dependent diabetics without diabetic retinopathy?

PURPOSE: To confirm the influence of multilevel metabolic disturbance of insulin dependent diabetes mellitus (IDDM) on the vision even before the onset of the other changes routinely evaluated by ophthalmologists. METHODS: Contrast sensitivity functions (CSFs) were estimated using the VCTS 6500 board. The standardised measurement procedure was performed. The value of the threshold contrast sensitivity was obtained for five spatial frequencies (1.5-3-6-12-18 c/deg). Other data was collected (duration of diabetes, BCVA, funduscopy, fluoresceine angiography, HbA1C). The study group consisted of 48 IDDM patients (94 eyes) without diabetic retinopathy and with Snellen BCVA > 1.0. The control group (56 normals, 98 eyes) was age and BCVA matched. RESULTS: Highly statistically significant decrease of the CSFs in all spatial frequencies in the study group was obtained. Correlation between duration of the diabetes and impaired degree of CSFs was present in the middle spatial frequency. No significant changes in CSFs were found among patients with pathological value of glycated hemoglobin HbA1c (> 7.8%). CONCLUSIONS: If compared with routinely used Snellen visual acuity, the CSFs are more complex descriptors of the subjects vision abilities. IDDM has an influence on these sensitive functions, especially during examination in the middle spatial frequency of 6 and 12 c/deg, before disturbing visual acuity and before changes in the retinal morphology. Decrease of CSFs was influenced mainly by the patients' age and partially (in the middle spatial frequency) by the IDDM duration.

Adult↗

PubMed1983

Effects of defocus on monkey (Macaca nemestrina) contrast sensitivity: behavioral measurements and predictions.

An observer's contrast sensitivity function (CSF) can be affected by degradation of either the optical or neural components of the visual system. In a continuing effort in this laboratory to separate these two components in infant and mature monkeys, we have measured behavioral CSF's with the retinal image defocused by as much as 6 D. With increased defocus, sensitivity decreases much more rapidly at high spatial frequencies than at low frequencies. Furthermore, we find that calculations of retinal image contrast, based upon available optical parameters of the monkey eye, underestimate the amount of optical defocus which still allows pattern detection by our monkeys at high spatial frequencies. Several possible explanations for this apparent conflict are discussed, including optical aberrations present in the primate eye, and the "spurious resolution" of defocused sinusoidal gratings.

Animals↗

PubMed1995

Individual differences in contrast sensitivity functions: longitudinal study of 4-, 6- and 8-month-old human infants.

Contrast sensitivity functions (CSFs) of 25 infants were measured longitudinally at 4, 6 and 8 months of age using a preferential-looking method and the method of constant stimuli. Sine-wave gratings varied from 0.27 to 4.32 c/deg, contained eight unattenuated cycles (with edges tapered to uniform gray), and rose to the desired contrast in 2 sec. (1) The average CSF was described on log-log coordinates by a band-pass function. With development it increased in overall sensitivity to contrast, shifted its peak toward slightly higher spatial frequencies, and increased its high frequency cutoff. (2) Log sensitivity at the CSF peak was slightly higher for female than male infants at 6 months, consistent with the hypothesis that vernier acuity (which also may differ between the sexes at this age) is partly mediated by analyzers tuned to low frequencies. (3) Within age groups the individual differences were such that log sensitivities for neighboring spatial frequencies generally correlated more highly than distant frequencies. With development the correlations among distant frequencies below 1.0 c/deg increased. Monte Carlo simulations of a model that shifts spatial analyzers to higher frequencies with age reproduced these results but simulations of adultlike, unshifting analyzers did not. (4) Measures taken 2 months apart tended to correlate more highly than those taken 4 months apart, though some individual differences in the CSF peak remained stable over 4 months.

Aging↗

PubMed1995

Effects of luminance and spatial noise on interferometric contrast sensitivity.

Optical properties of the eye contribute to the reduced visibility of spatial patterns at low luminance. To study the limits of spatial vision when optical factors are minimized, we measured contrast-sensitivity functions (CSF's) for 543.5-nm laser interference fringes imaged directly on the retina. Measurements were made in the fovea at four luminance levels, ranging from 0.3 to 300 photopic trolands (Td). At each luminance the fraction of coherent light in the stimulus pattern was varied to assess the masking effects of laser speckle, which is visible as spatial noise in fields of coherent light. Compared with published CSF's obtained under natural viewing conditions, interferometric CSF's were similar in height but broader, with the range of visibility being extended to higher spatial frequencies. The masking effects of speckle were greatest at the highest luminance and were negligible at the lowest luminance. For low coherent fractions, contrast sensitivity improved over the entire luminance range at a rate consistent with a square-root law; with purely coherent light, sensitivity tended to level off at approximately 30 Td because of speckle masking. The results indicate that the optical quality of the eye reduces the spatial bandwidth of vision even at luminances near the foveal threshold. The change in interference fringe visibility with luminance is consistent with noise-limited behavior, and the masking effects of speckle noise diminish as luminance decreases.

Adult↗

PubMed1987

Performance of amblyopic children on printed contrast sensitivity test charts.

Forty consecutive amblyopic patients between the ages of 3 and 12 years attending the Orthoptic Clinic for assessment and treatment were tested on the AO Contrast Sensitivity System [Arden grating test (AGT)] and the VISTECH Contrast Sensitivity Charts. Recordings were unsuccessful in more than 50% of these patients on both test systems. Of those who could successfully complete the AGT, false negative results were noted in 62.5% of the amblyopic eyes and false positive results were found in 25% of the normal fellow eyes. On the near VISTECH chart, all normal and amblyopic eyes produced results that were outside the specified limit of normality. On the distance VISTECH chart, 25% of the normal fellow eyes gave false positive results and 25% of the amblyopic eyes gave false negative results. From these findings, it is doubtful whether either test system has a role in the routine clinical assessment of amblyopia.

Amblyopia↗

PubMed1986

Comparative study of electrophysiological and psychophysical measurement of the contrast sensitivity function in humans.

We measured the human contrast sensitivity function (CSF) both electrophysiologically with the steady-state visual evoked potential (VEP) and psychophysically using a method of ascending limits. VEP contrast thresholds were determined using a rapid recording technique in which the contrast of a counterphase modulated sine wave grating was swept logarithmically from 0.5 to 40% over a period of 10 s. For this pattern reversal stimulus the amplitude and phase of the second harmonic response as a function of contrast were measured using a discrete Fourier transform (DFT). Psychophysical thresholds were determined on the same trials used to record the VEP. Near threshold the VEP amplitude vs. contrast function was approximately linear and VEP contrast thresholds were estimated by a linear extrapolation to zero amplitude. The contrast thresholds obtained by the two methods correlated at 0.914 for 5 observers, with a mean discrepancy of only 12%. At higher contrasts, the VEP amplitude vs. contrast function often became nonmonotonic, sometimes showing two amplitude peaks.

Electrophysiology↗

PubMed1998

Do visual-evoked potentials and spatiotemporal contrast sensitivity help to distinguish idiopathic Parkinson's disease and multiple system atrophy?

A large number of patients with Parkinson's disease were reported to have abnormal visual-evoked potentials (VEPs) and spatiotemporal contrast sensitivity (STCS) suggesting dopaminergic deficiency in the visual pathway, probably the retina. Until now, VEPs and STCS have not been studied in multiple system atrophy (MSA). We investigated 12 patients with idiopathic Parkinson's disease (IPD) and 12 patients with MSA. The age medians were 64.5 years for IPD and 63.5 years for MSA. None of the patients showed any ocular disease that could interfere with the results. Checkboard VEPs and STCS measurements to horizontal sinusoidal gratings were evaluated. Statistical analysis was performed, including Student's t test and two- or three-way analysis of variance. A significant interocular difference in spatial contrast sensitivity was observed in IPD, which was not present in MSA. VEPs were not delayed in MSA, whereas latency of the major component and the second negative deflection were increased in IPD. VEPs and STCS measurements might provide useful help for distinguishing IPD from MSA.

Aged↗

PubMed2003

Topographic change in the central macula coupled with contrast sensitivity loss in diabetic pregnancy.

PURPOSE: To study macular topography and contrast sensitivity (CS) in diabetic and nondiabetic women during pregnancy and post partum. METHODS: A prospective study of 46 pregnant women with insulin-dependent diabetes and 11 nondiabetic pregnant controls. Macular surface topography was analyzed by Heidelberg Retinal Tomograph. Volume above the reference plane (VARP) was measured with 1.0-, 1.5-, 2.0-, and 3.0-mm-diameter circles. CS was measured with the Vistech 6500 Contrast Test System. RESULTS: The diabetic women had greater VARP than the controls measured with the 1.5-mm diameter circle. In diabetic women, the mean VARP was 0.084+/-0.064 mm(3) (mean +/- SD) in the first trimester, 0.080 +/- 0.056 mm(3) in the third trimester, and 0.087 +/- 0.067 mm(3) 3 months post partum compared with the values of 0.069+/-0.043, 0.054+/-0.024, and 0.036+/-0.020 mm(3) in the controls ( P=0.036 between groups). In diabetic women requiring laser treatment, the difference from controls was more significant ( P<0.001). CS at 3 cpd and 6.0 cpd was lower in diabetic women than in controls throughout pregnancy and post partum ( P=0.012 and P=0.043). A statistically significant negative correlation appeared between macular topography and CS during the third trimester; between cpd 6 and VARP 1.5 mm ( r=-0.471, P=0.001), and between cpd 6 and VARP 2.0 mm ( r=-0.446, P=0.002). CONCLUSIONS: In the diabetic women, especially in those with clear progression of retinopathy during pregnancy and post-partum, the macula seemed to be slightly more elevated than in the controls, and CS was lower at mid-range spatial frequencies. CS loss in the diabetic women correlated with macular elevation during the third trimester.

Case-Control Studies↗

PubMed1992

Isoluminant stimuli may not expose the full contribution of color to visual functioning: spatial contrast sensitivity measurements indicate interaction between color and luminance processing.

Visual performance is greatly impaired when tested with heterochromatic isoluminant stimuli. It is thus concluded that the chromatic system contribution to many visual tasks is limited. We suggest that unless color and luminance are shown to be processed independently, such experiments do not demonstrate shortcomings of the chromatic system but rather the inadequacy of using isoluminant stimuli for isolating that system. We hypothesize that color vision has evolved not only to encode color per se but also to enhance luminance-based visual processing, so that for color information to be fully effective, luminance as well as chromatic variations should be present in the stimulus. The hypothesis was tested by studying the contribution of color to spatial vision. The human contrast sensitivity function (CSF) was studied using luminance, isoluminance (color) and combined luminance/color sinusoidal gratings. It is found that luminance contrast sensitivity is enhanced when luminance contrast is accompanied by color contrast and vice versa. The nature of the interaction is best described by an additive single analyzer model. Color opponent cells which respond to both chromatic and achromatic stimuli may be identified as the analyzer.

Color Perception↗

PubMed1985

Dopaminergic drugs improve human visual contrast sensitivity.

Effects of dopaminergic drugs (L-dopa plus benserazide, or nomifensine) on human visual function have been tested in healthy volunteers by measuring the psychophysical contrast sensitivity for sinusoidal gratings of various spatial frequencies. After drug administration the contrast sensitivity improved in all subjects over a limited range of medium to high spatial frequencies.

Adult↗

PubMedDate not supplied

[Spatial contrast sensitivity in patients with high myopia after refraction lamellar keratoplasty].

Spatial contrast sensitivity (SCS) is one of the most important visual functions. SCS was examined in 23 patients (38 eyes) with high myopia before and after refraction lamellar keratoplasty (RLK) and in 21 healthy controls. Before surgery an appreciable (p < 0.01) reduction of SCS was observed in patients with high myopia in the entire range of spatial frequencies in comparison with the controls. After the operation the maximally corrected vision acuity was virtually unchanged, whereas the parameters of SCS somewhat increased for all frequencies, the increase being statistically reliable at frequencies of 0.23 to 3.75 and 15 cycles/degree. Hence, the studies demonstrated that changes in the topography of the cornea after refraction lamellar keratoplasty do not deteriorate the visual function.

Contrast Sensitivity↗

PubMed1998

Retinal function in Swedish ophthalmologists using argon lasers as reflected in colour contrast sensitivity. Normal thresholds in the great majority of the cases.

PURPOSE: To map the colour contrast sensitivity (CCS) and possible elevations of colour contrast thresholds in Swedish ophthalmologists operating argon lasers. MATERIAL AND METHODS: CCS was measured by a computer and colour monitor system developed by Arden and co-workers. CCS of 58 Swedish ophthalmologists, all users of argon laser, was compared to 26 age-matched controls. The ophthalmologists provided information on their professional use of lasers, whether the laser was equipped with a blue-absorbing filter, and the length of time spent in retinal surgery. RESULTS: There was no significant difference in colour vision comparing laser-users to controls (p>0.2). However, eight subjects showed elevated tritan thresholds (>1 SD above mean), in three of the cases an elevation >2 SD above mean. All these colleagues had an extensive exposure to blue-green laser and/ or a long time spent operating. Compared to others, they had performed more laser sessions prior to the lasers being equipped with protecting filters (p<0.01). CONCLUSION: Normal thresholds were found in a majority of the cases and no permanent impairment of retinal function was observed among these ophthalmologists. However, the laser-users with the greatest number of sessions seemed to show a certain decrease in retinal function as reflected in tritan thresholds.

Adult↗