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PubMed2004

Orientational contrast sensitivity and chromatic contrast thresholds in multiple sclerosis.

PURPOSE: To investigate abnormalities of orientational contrast sensitivity (CS) and chromatic contrast threshold (CCT) in multiple sclerosis (MS). DESIGN: Case control study. METHODS: Nine subjects (mean age, 42 +/- 11 years; range, 20-62 years) with MS, an expanded disability status scale of 3 or less, and normal visual acuity (VA) (logarithm of the minimum angle of resolution [logMAR] VA less than.1) in the tested eye were age-matched with 20 controls. Achromatic CS and CCT were measured using static, computer-generated sinusoidal gratings displayed on a high-resolution monitor. The CS and CCT of each subject were determined using a randomized double-staircase reversal algorithm; CS was measured at five spatial frequencies with horizontal orientation and three with vertical orientation; CCT was measured along the red-green and tritan confusion axes. The sensitivity thresholds of subjects were examined in relation to the mean sensitivity of controls for each spatial frequency. RESULTS: Two subjects had loss of horizontal and vertical CS, and three had isolated vertical loss. When compared with the control mean, there were significant reductions in red-green (P =.016) and tritan (P =.016) discrimination thresholds. CONCLUSION: This study used a computerized psychophysical test designed to minimize many of the test errors associated with earlier studies. It provides confirmatory evidence that MS may be associated with a loss of orientational CS and color vision, in the absence of reduced VA.

Adult↗
PubMed1988

Jogging and contrast sensitivity.

Threshold contrast sensitivity was measured using sinusoidal gratings with the method of increasing contrast both before and after jogging in fresh air. The mean contrast sensitivity of 11 subjects was higher after jogging at all three spatial frequencies studied (1, 6 and 19 c/deg). The differences were statistically significant. The effect of jogging was subject to individual variation, some 'unstable' subjects responding strongly and some 'stable' subjects showing no change at all. Two 'unstable' subjects were tested several times, and their strong response proved to be repeatable.

Adult↗
PubMed1999

Senescent changes in scotopic contrast sensitivity.

Scotopic contrast sensitivity functions (CSFs) were measured for 50 observers between the ages of 20 and 88 years. Using a maximum-likelihood, 2-alternative, temporal forced-choice threshold-estimation algorithm, scotopic CSFs were measured at 7 spatial frequencies ranging from 0.2 to 3.0 cpd, with mean retinal illuminance equated for observers at -0.85 log scotopic Trolands. For each stimulus condition, eight cycles of a horizontal sinusoidal grating were presented within +/- 1 S.D. of a 2-D Gaussian-spatial envelope and within a 1-s Gaussian-temporal envelope. Stimuli were centered on the nasal retina along the horizontal meridian 6 degrees from the fovea. Scotopic CSFs were found to be low-pass. Statistically significant age-related declines in contrast sensitivities were found for spatial frequencies at or below 1.2 cpd. There was also a statistically significant decrease in the high frequency cut-off with age (P < 0.01). An explanation of these results in terms of optical factors is rejected, while the results are consistent with age-related changes in the magnocellular pathway.

Adult↗
PubMed1991

Assessment of contrast sensitivity. Part II: The relationship between objective lens opacity and laser interferometric contrast sensitivity in the cataract patient.

The laser interferometer can effectively bypass the optics of the eye and measure retinal function in patients with immature cataracts. However, it is not known how much laser interferometric measurements are impaired by cataract density. In this study we compared objective lens opacity using the IntraOptics opacity lensmeter with contrast sensitivity (CS) measured by a Randwal He-Ne laser interferometer. Comparison of lens opacity with CS in the cataract population revealed an inverse linear relationship between objective lens opacity and retinal contrast sensitivity. Separation by cataract type showed correlation coefficients as high as -0.91 for nuclear sclerotic predominant cataracts and as low as no significant correlation for posterior subcapsular predominant cataracts. Comparisons of before and after implantation surgery contrast sensitivities (as measured by the laser interferometer) with preoperative lens opacities (as measured by the IntraOptics opacity lensmeter) quantified the extent to which laser interferometric measurements underestimated potential retinal function. We found that for all cataracts, other than posterior subcapsular predominant cataracts, potential contrast sensitivity (in decibels) was underestimated by about 0.2 to 0.3 times the opacity measured by this technique.

Adult↗
PubMed1986

Population norms for edge contrast sensitivity.

The contrast sensitivity (CS) for a single edge appears to be a reliable indicator of the peak of the contrast sensitivity function (CSF). We propose that for general clinical practice and in the functional assessment of patients with low vision, the simple measurement of edge CS provides an adequate indicator of the peak of the CSF. We conducted a trial in which edge CS was measured in a routine clinic setting.

Aging↗
PubMed1988

A system for controlled presentation of the Arden contrast sensitivity test.

Contrast sensitivity has been identified as a significant index of visual function, and as an indicator of visual disorders. The Arden test of contrast sensitivity has been recognized as a simple and easily administered technique for measurement of this process. However, the customary method of administration of this test involves manual manipulation and considerable individual subjectivity. The instrument described in this report was designed and developed to minimize variability in the testing procedure due to differences in individual testing techniques, and to standardize testing conditions, ambient illumination, viewing distance and rates of presentation.

Fourier Analysis↗
PubMed1983

Comparison of three methods for rapid determination of threshold contrast sensitivity.

Threshold contrast sensitivity functions for 13 subjects were determined on 5 consecutive days using three psychophysical methods. Each method was implemented on a microprocessor controlled display system and considered as a possible candidate for a rapid visual screening test. The methods used were Bekesy tracking, method of adjustment, and method of increasing contrast. The method of increasing contrast proved superior to the other methods in repeatability, speed, and the preservation of individual differences in contrast sensitivity over the testing period.

Form Perception↗
PubMed1979

Age variations in normal human contrast sensitivity.

The visual contrast sensitivity (the reciprocal of contrast threshold) was studied as a function of age. Psychophysical measurements of binocular and monocular contrast thresholds were made for 33 normal observers at spatial frequencies within the range 0.5 to 40 cycles/degree. The observers were divided into three different age groups: young, middle-aged, and old subjects with the age ranges 6--10 years, 20--40 years, and 60--70 years, respectively. All observers had healthy eyes, normal vision, and Snellen visual acuity of 1.0 or better in both eyes. In all groups, contrast sensitivity for binocular and monocular viewing peaked at a spatial frequency around 3--5 cycles/degree and showed the typical attenuation at low and high spatial frequencies. The binocular contrast sensitivity was higher than the monocular. There was no significant difference between young and middle-aged subjects with regard to contrast sensitivity. Subjects aged 60 years or more showed significantly lower contrast sensitivity than younger subjects for most spatial frequencies above 4 cycles/degree. We may thus conclude that both the binocular and monocular contrast sensitivity seemed independent of age within the range of 6 to 40 years. For higher ages studied (above 60 years), there was a loss of sensitivity in the middle and high frequency regions.

Adolescent↗
PubMed1992

Binocular contrast summation and inhibition in amblyopia. The influence of the interocular difference on binocular contrast sensitivity.

The monocular contrast sensitivity loss in amblyopia is well documented. We investigated the influence of interocular sensitivity difference on binocular contrast sensitivity in amblyopia. Monocular and binocular contrast sensitivity functions of six amblyopes (three strabismic and three anisometropic) were measured. The monocular contrast sensitivity loss depended on the type of amblyope. Anisometropic amblyopes generally showed high frequency losses. Strabismic amblyopes showed losses at both low and high spatial frequencies. Binocular performance was assessed in terms of binocular ratios (binocular/non-amblyopic). A binocular ratio greater than 1 indicates binocular summation (binocular > monocular) while a ratio less than 1 shows binocular inhibition (binocular < monocular). In all subjects, the binocular ratio depended on the difference between the amblyopic and the non-amblyopic eye. Minimal interocular difference produced binocular summation, the magnitude of which decreased as the difference between the two eyes increased. Further increases in the monocular difference produced binocular inhibition. Anisometropic amblyopes showed a greater degree of binocular summation at low spatial frequencies compared to strabismic amblyopes. Both types of amblyopes showed binocular inhibition at high spatial frequencies. Clinical implications of binocular summation and inhibition in amblyopia are discussed.

Adolescent↗
PubMed2006

Clinical assessment of two new contrast sensitivity charts.

BACKGROUND: Contrast sensitivity measurement in UK clinical practice is most commonly performed with the Pelli-Robson chart. AIMS: To compare the repeatability of two new contrast sensitivity charts and to measure their agreement with the Pelli-Robson charts. METHOD: Contrast sensitivity was measured monocularly using two versions of the Mars letter contrast sensitivity chart, two presentations on the Test Chart 2000 and two versions of the Pelli-Robson chart. Bland-Altman techniques were used to assess repeatability and agreement. RESULTS: 53 subjects were recruited with visual acuity from 6/4 to 6/72. The coefficient of repeatability was 0.182 for the Pelli-Robson chart, 0.121 for the Mars chart and 0.238 for Test Chart 2000. Limits of agreement with the Pelli-Robson chart were -0.29 to +0.15 log units for the Mars letter contrast sensitivity chart and -0.32 to +0.78 log units for the Test Chart 2000. For patients with poor contrast sensitivity, the limits of agreement between the Test Chart 2000 and the Pelli-Robson chart improved from -0.33 to +0.15 log units. CONCLUSION: In a population of hospital ophthalmology patients, the coefficient of repeatability is better for the Mars chart and worse for the Test Chart 2000 when compared with the Pelli-Robson chart. The electronic test chart does not agree well with the Pelli-Robson chart, although this might simply be due to the performance of liquid crystal display screens at low contrast levels. The Mars letter contrast sensitivity chart shows good validity and reasonable agreement with the Pelli-Robson chart.

Adult↗
PubMed2003

Influence of occupational exposure to organic solvent mixtures on contrast sensitivity in printers.

Contrast sensitivity measurement accurately evaluates the sensitivity of all human visual channels, even in a more detailed manner than simple acuity measures can. This is a study of visual contrast sensitivity in a series of subjects occupationally exposed to organic solvents. Contrast sensitivity was measured for 42 printers and 28 age-stratified controls using the Vistech VCTS 6500 chart. The exposed workers distinguished between following three groups of printers: "low exposed," "middle exposed," and "high exposed." Abnormal contrast sensitivity results were recorded for the right eye in 38% of the printers and 11% of the controls and for the left eye in 38% of the printers and 7% of the controls. Especially, we found a reduced contrast sensitivity in all three groups exposed to solvents for both eyes. We conclude that contrast sensitivity is abnormal in workers exposed to organic solvents. The reduced contrast sensitivity in printers seems to be an indicator of visual defects induced in response to organic solvents exposure.

Adult↗
PubMed2001

Effect of size of attended area on contrast sensitivity function.

Contrast sensitivity functions (CSFs) were measured in the foveal region while subjects simultaneously performed an instantaneous judgment task, which was designed to maintain their attended areas at a constant size. Spatial attention was sustained over areas that were either narrow (Narrow condition) or broad (Broad condition). We observed that the sensitivity at higher frequencies (over 3 cpd) was greater under the Narrow condition than that under the Broad condition, supporting the argument that attention enhances spatial resolution.

Attention↗
PubMed2006

[Multidisciplinary use of contrast sensitivity].

BACKGROUND: Contrast sensitivity (CS) gives information about quality of different spatial frequency sent from sensory cells to the brain cortex through different pathways. METHODS AND RESULTS: From the age of 6 to 10 years average CS threshold was defined for each frequency. 3c/deg=1,82 (SD 0,13), 6 c/deg=2,04 (SD 0,14), 12 c/deg=1,74 (SD 0,15), 18 c/deg=l,29 (SD 0,11). In the age between 11 and 19 years following values were determined: 3c/deg=1,92 (SD 0,09), 6 c/deg=2,19 (SD 0,12), 12 c/deg=1,89 (SD 0,10), 18 c/deg=1,42 (SD 0,12). There was no significant difference between each frequency on CS curve. Average threshold for all frequencies was the 6th contrast level of circle in younger children and the 7th contrast level of circle in older. According to the standard deviations the threshold for all the frequencies was the 5th contrast level of circle in children from 6 to 10 and the 6th contrast level of circle in children older then 11. As the CS can be distorted by hidden form of anisometric amblyopia, proper correction of refractive error is essential. CS helps to detect hidden neuropathy in Graves disease or in Septo-optic dysplasia. Initial stages of demyelinisation of optic nerve in Multiple Sclerosis are manifested always by decrease of CS. This helps to evaluate the affection of the optic pathway and CNS in Alzheimer disease, in Parkinson's disease and schizophrenia. Decrease of CS goes along with retinopathy and with some forms of preretinopathy in Diabetes mellitus. Dynamic changes of CS can be related to treatment of several diseases including Cystic fibrosis, Chronic renal insufficiency, Neonatal hypothyreosis, Menopause or Osteoporosis. CONCLUSIONS: Author proves that CS can be reliably examined using the device CSV-1000 in children from the age of 6 years within the framework of multidisciplinary use.

Adolescent↗
PubMed1995

Alcohol consumption and visual contrast sensitivity.

Visual contrast sensitivity (VCS) was measured in 30 alcoholic patients and 52 controls. The results showed a significant reduction in VCS for all the spatial frequencies. The mean reduction for all spatial frequencies was 2.49 dB below the level of the control group. Optimal sensitivity corresponded to a lower spatial frequency in patients than controls, i.e. 1 cycle/degree (c/d) versus 2 c/d. Curves for VCS were normal for five patients. Abnormalities in VCS were suggestive of optic nerve dysfunction for 15 patients (50%), which were probable in seven cases (23%) and possible in eight others (27%). For 10 subjects, the abnormalities were indicative of ametropia. Daily alcohol intake and daily tobacco consumption were not significantly different in the patients who displayed VCS abnormalities, reflecting alcohol-tobacco amblyopia, from those who did not. The presence of higher gamma-glutamyl transpeptidase and mean corpuscular volume levels in patients who had VCS abnormalities indicative of alcohol-tobacco amblyopia suggests that alcohol consumption is involved in the development of these abnormalities.

Adult↗
PubMed1982

A forced-choice test improves clinical contrast sensitivity testing.

Decreased contrast sensitivity has been demonstrated in early glaucoma, but the deficit in not regularly observed. We designed a prototype for a forced-choice printed test and evaluated it with several other measures of contrast sensitivity. The results also bear on the pattern of loss and the variables which effect performance. Mildly glaucomatous patients show at 6 db (50%) loss of contrast sensitivity at all spatial frequencies tested compared with age matched controls. Moving gratings give the same information as stationary ones, and practice effects are negligible. Contrast sensitivity at or below 2 cycles/degree is poorly correlated with visual acuity and does not change with age in the forced-choice test. Subjective judgment made the apparent contrast threshold higher, age dependent, and more variable, particularly at higher spatial frequencies. The pattern of variability can explain some reports of insignificant effects and why low spatial frequency contrast sensitivity detects glaucoma better than visual acuity. Methods correlated so poorly, despite high reliabilities, that uncontrolled biases must be suspected in subjective measures. Our new forced-choice format was superior to all other tests on at least one formal criterion and always at least equal to them. Improvements in contrast sensitivity screening tests are thus indicated.

Adolescent↗
PubMed1993

Contrast sensitivity in 24- and 36-month-olds as assessed with the contrast sensitivity card procedure.

We used a new card procedure to evaluate binocular contrast sensitivity (CS) in 24- and 36-month-old children. The test consists of 40 large (50 by 28 cm) matteboard cards, each of which contains a sine wave grafting with 1 of 5 spatial frequencies (0.4, 0.8, 1.6, 3.2, and 4.8 cpd at 80 cm) and with 1 of 8 contrast levels [from 33% (CS = 3) to 0.4% (CS = 260)]. Estimates of subjects' CS to each spatial frequency were obtained with a modified forced-choice preferential looking (FPL) technique similar to that developed for the Teller Acuity Cards (TAC). All 36-month-olds and 74% of the 24-month-olds completed the entire procedure in an average of 12 min per child. For both groups, the shape of the mean constant sensitivity functions (CSF's) resembled the characteristic inverted U shown by normal adults, except that the toddlers' functions were shifted to lower contrasts and spatial frequencies. Combined with previous results, it appears that the CS cards hold promise as a time-efficient means of assessing CS in infants and young children, and may provide the prototype for a clinical tool to help detect early visual and neurological dysfunction.

Child, Preschool↗
PubMed1988

Effect of visual blur on contrast sensitivity. Clinical implications.

Contrast sensitivity of normal subjects was measured under conditions of refractive blur that produced specific levels of visual acuity. Measurements were made at distance (with Vistech charts), at near (with Arden gratings), and with a pinhole to control pupil size. Under all conditions, when visual acuity was reduced by spherical lenses, there was a loss of contrast sensitivity over a broad range of spatial frequencies (i.e., not just at the higher frequencies that correlate with target letter size). By inference, it may be clinically hazardous to interpret contrast sensitivity results in patients with reduced acuity (from any cause) relative only to standard contrast sensitivity values based on subjects with normal visual acuity. If the potential effects of acuity are taken into account, contrast sensitivity testing can distinguish between deficits that are roughly equivalent to the loss of acuity and those which indicate more distinctive pathology of the media, retina, or optic nerve.

Humans↗
PubMed1996

Effects of tinted intraocular lens on contrast sensitivity.

We evaluated contrast sensitivity and glare in 64 pseudophakic eyes. An ultraviolet-absorbing intraocular lens (IOL) was implanted in 32 eyes and a noncyanopsia yellow-tinted IOL was implanted in 32 eyes. The latter lens was designed to effectively absorb light below a wave-length of 500 nm. Contrast sensitivity was measured at a pupil diameter of 3 mm using an artificial pupil. The implanted yellow-tinted IOL showed improved contrast sensitivity in the middle spatial frequencies of 6 and 12 c/deg in photopic and mesopic vision. In addition, the yellow-tinted IOL decreased the effect of central glare on the contrast sensitivity.

Aged↗