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PubMed1991

A comparison of clinical acuity and contrast sensitivity charts: effect of uncorrected myopia.

We have examined the effect of corrected and uncorrected myopia on visual acuity and contrast sensitivity using a standard acuity chart and two commercially available printed contrast sensitivity charts (Vistech and Pelli-Robson). We tested 140 eyes of 70 young adults. Most subjects were myopic and were tested with and without their optimum spectacle or contact lens correction. We found no effect of myopia, if well corrected, on acuity or contrast sensitivity. All three test scores were sensitive to uncorrected myopia. The Pelli-Robson contrast sensitivity chart, which was designed to be insensitive to defocus, required more than three diopters of refractive error to elicit a two line change in performance, and it was generally very insensitive to uncorrected myopia. Although the Vistech chart was sensitive to uncorrected myopia, the large step sizes used in the chart, and the higher inter- and intra-subject variability in scores reduces its potential value for refraction. The Snellen letter chart gave the most sensitive and reliable changes in performance with uncorrected myopia.

Adult↗
PubMed1980

Detection of visual defects using the contrast sensitivity function.

In this chapter the theoretical reasons were outlined and clinical data summarized as to why spatial contrast measurements can reveal visual losses that are not uncovered by testing visual acuity, no matter which optotype one uses or how carefully the measurement is made. Spatial contrast sensitivity measurements may disclose different types of contrast losses in patients with different lesions but with identical visual acuity. The relationship of different types of spatial contrast sensitivity losses (plotted as visuograms) to specific location or cause of lesions is not yet clear. Patients with glaucoma show losses that occur infrequently in other types of eye or visual pathway diseases, but the specificity of the typical contrast loss needs confirmation. The definite clinical value of contrast sensitivity measurements is that they can identify incipient abnormalities in the visual pathways that subserve foveal vision. In addition to this definite diagnostic application, using sinusoidal gratings as stimuli for both contrast sensitivity and for VEP measurements is useful in a research-oriented clinical testing facility.

Amblyopia↗
PubMed1987

Visual dysfunction in Parkinson's disease. Loss in spatiotemporal contrast sensitivity.

Flicker sensitivity and spatial contrast sensitivity (CS) were examined in a total of 99 patients with Parkinson's disease (PD). All patients were undergoing treatment with dopaminergic agents. Specific losses in sensitivity observed in PD were (1) a loss in flicker sensitivity which was most pronounced around the peak of the function (8 Hz) and (2) a loss near the peak of the spatial CS curve, often with no noticeable low frequency attenuation. Several PD patients affected by the 'on-off' syndrome were tested in both 'on' and 'off' phases, and the results show that the CS function switches in parallel with motor symptoms of the disease. These data suggest that not only is the visual system affected in PD, but that dopamine may have an essential role in receptive field organization in human vision.

Adult↗
PubMed1993

Development of infant contrast sensitivity to chromatic stimuli.

We have monitored the development of contrast sensitivity to equiluminant red-green chromatic patterns by monitoring visual evoked potentials (VEPs) in 13 infants. The results confirm our previous report [Morrone, Burr and Fiorentini, Proceedings of the Royal Society B, 242 (1990a)] that, before 7-8 weeks of age, there was no response to purely chromatic stimuli, while at the same age luminance stimuli of 20% contrast produced reliable responses. At all ages (even before the onset of a chromatic response) the colour mixture to yield equiluminance was similar to that of adults, suggesting that the relative proportion and efficacy of medium- and long-wave cones is similar for infants as for adults. For both luminance and chromatic stimuli, amplitude increased roughly linearly with log-contrast, so sensitivity thresholds could be predicted by linear extrapolation to the abscissa. Detailed contrast sensitivity curves were measured for four infants at various ages. The results show that luminance and chromatic contrast sensitivity develop independently at different rates, probably reflecting differential development of postreceptoral neural mechanisms.

Age Factors↗
PubMed1977

Contrast sensitivity in macular disease. A preliminary report.

Psychophysical measurements of contrast thresholds for sinusoidal gratings of variable frequency were made in normal controls and in patients with macular disease. Normal controls showed a U-shaped contrast sensitivity function comparable with previous reports. Patients with relatively well conserved visual acuity showed a marked impairment in contrast sensitivity for targets of high and intermediate spatial frequencies, while patients with more advanced disease showed a pronounced impairment across a larger spectrum of frequencies. Our findings provide insight into the visual difficulties of daily life of patients with macular disease. The determination of contrast sensitivity seems to be an important and very sensitive tool for the detection of early disturbances.

Adult↗
PubMed1992

Contrast sensitivity as a function of spatial frequency, viewing distance and eccentricity with and without spatial noise.

Using computer graphics and a two-alternative forced-choice method we measured threshold contrast as a function of viewing distance, spatial frequency, and eccentricity for gratings with and without added, white two-dimensional spatial noise. Our experiments showed that in spatial noise contrast sensitivity was independent of viewing distance as long as contrast sensitivity was lower with noise than without. With increasing spatial frequency (f) the grating area (A) was reduced in order to keep the relative grating size (Af2) constant. At all spatial frequencies the test gratings thus had the same amount of detail and contour. Noise spectral density was reduced in direct proportion to grating area in order to keep the physical signal-to-noise ratio constant. An increase in spatial frequency was thus accompanied with reductions in grating area and noise spectral density similar to those produced by a corresponding increase in viewing distance. In agreement, contrast detection in spatial noise was found to be independent of spatial frequency as long as contrast sensitivity was lower with noise than without. The effect of increasing eccentricity on visual performance can be compensated for by reducing the viewing distance (M-scaling). Hence, without M-scaling the effect of increasing eccentricity is similar to that of increasing viewing distance. In agreement, we found that contrast sensitivity in spatial noise was independent of eccentricity as long as contrast sensitivity was lower with noise than without.

Adult↗
PubMed1993

Contrast sensitivity peripheral to an absolute central scotoma in age-related macular degeneration and the influence of a yellow or an orange filter.

Contrast sensitivity for static and dynamic gratings was determined in 17 patients with age-related macular degeneration (AMD) and an absolute central scotoma. Using electronic and computerized equipment, we established contrast sensitivity peripheral to the scotoma at spatial frequencies of 0.5, 1.0 and 2.0 cycles/degree. We found that mean contrast sensitivity was significantly (p < 0.001) lower than that of a control group at a comparable eccentricity, and that interindividual variations were large. Furthermore, we investigated the influence of a yellow and an orange filter on contrast sensitivity peripheral to such an absolute central scotoma in AMD. The results showed significant (p < 0.01-0.05) improvements in contrast sensitivity at certain spatial frequencies only, i.e., for the yellow filter at 2.0 c/deg and for the orange filter at 0.5 and 1.0 c/deg, and only with dynamic presentation. No objective improvement in visual acuity could be demonstrated when using filters. Thus, our findings do not unequivocally support the regular prescription of such filters in order to improve contrast vision in AMD with an absolute central scotoma.

Aged↗
PubMed1994

Low luminance contrast sensitivity: effects of training on psychophysical and optokinetic nystagmus thresholds in man.

We compared psychophysical contrast sensitivity function (psi-CSF) and optokinetic contrast sensitivity function (OKN-CSF) in man, for the combination of three spatial and three temporal frequencies. psi-CSF was defined as the inverse of the contrast threshold, that is the contrast value of a sinusoidal grating for which a subject was able to identify the width of a drifting grating. OKN-CSF was defined as the inverse of the contrast value of the grating which triggered an involuntary optokinetic nystagmus. In highly experienced subjects, OKN-CSF was overall higher than psi-CSF. More precisely, differences between both contrast sensitivity functions occurred mainly in the low spatio-temporal frequency range (below 4 c/deg and 9 Hz). In naive subjects, psi-CSF reached the level of OKN-CSF after two consecutive test sessions. OKN-CSF did not change with training. Similarly, high spatio-temporal frequency psychophysical thresholds did not change with training and, moreover, approximated OKN-CSF thresholds. Low spatio-temporal frequency psychophysical sensitivity was initially lower than corresponding OKN-CSF sensitivity; however, after only two training sessions, the two functions were indistinguishable due to a selective increase in psychophysical low spatio-temporal frequency sensitivity.

Adult↗
PubMed1990

Contrast sensitivity in patients with a new type of multifocal intraocular lens.

Contrast sensitivity was measured in 13 pseudophakic eyes of ten patients who had a new type of diffractive multifocal intraocular lens (IOL) and compared with an age-matched control group with a conventional monofocal IOL. All selected cases had a postoperative follow-up of four to six months and a corrected visual acuity of 20/20 or better. For distance vision, no significant difference in contrast sensitivity could be found between the two groups, indicating an uncompromised distance focus of the multifocal IOL. For near vision, an overall decrease in the contrast sensitivity of 0.19 log units (mean value across the tested frequency from 1.5 to 18 cycles/deg) was found in the multifocal group when these patients were tested without near addition and compared with the controls with near addition (P less than .05). This indicated the near focus of the multifocal IOL to be somewhat less efficient than the far focus. We find these results promising for the new diffractive multifocal IOL.

Accommodation, Ocular↗
PubMed1990

Color and contrast sensitivity in the lateral geniculate body and primary visual cortex of the macaque monkey.

We tested color and contrast sensitivity in the magnocellular and parvocellular subdivisions of the lateral geniculate body and in layers 2, 3, 4B, and 4C alpha of visual area 1 to obtain physiological data on the degree of segregation of the 2 pathways and on the fate of the color and contrast information as it is transmitted from the geniculate to the cortex. On average, magnocellular geniculate cells were much less responsive than parvocellular cells to shifts between 2 equiluminant colors. Nevertheless, many magnocellular cells (though not all) continued to give some response at equiluminance. As expected from previous studies, luminance contrast sensitivity differed markedly between magnocellular and parvocellular layers. In V-1, the properties of cells in the magnorecipient layers 4C alpha and 4B faithfully reflected the properties of magnocellular geniculate cells, showing no evidence of any parvocellular input. Like magnocellular geniculate cells, they showed high contrast sensitivity, and with color contrast stimuli they showed large response decrements at equiluminance. In the interblob regions of cortical layers 2 and 3, which anatomically appear to receive most of their inputs from parvorecipient layer 4C beta, contrast sensitivities of some of the cells were compatible with a predominantly parvocellular input. Other interblob cells had sensitivities intermediate between magno- and parvocellular geniculate cells, suggesting a possible contribution from the magnocellular system. Many cells in cortical layers 2 and 3 responded to color-contrast borders equally well at all relative brightnesses of the 2 colors, including equiluminance. We recorded from many direction- and disparity-selective cells in V-1: most of the direction-selective and all of the clearly stereo-selective cells were located in layer 4B.

Animals↗
PubMed1994

A forced choice procedure for evaluation of contrast sensitivity function in preschool children.

BACKGROUND: The ability to clinically use Contrast Sensitivity Function (CSF) in adults for detection of visual pathway disorders has been demonstrated. The results of CAF testing would be especially meaningful clinically for young children for earlier diagnosis and treatment of visual disorders. In preschool children (ages 3-5 years), CSF assessment has been more laborious and less practical clinically and has met with limited use or success when dealing with preschool children. The purpose of this study was to evaluate the effectiveness of a modified two-alternative forced choice (2AFC) procedure in testing the CSF in preschool children. METHODS: The subjects in this study consisted of 26 children between the ages of 35 and 60 months of age. The children were free of any detectable visual deficits, illness, and neurological or developmental abnormalities. A Vistech Vision Contrast Sensitivity System (CTS 6500) chart was modified and applied in a two-alternative forced choice procedure to determine the contrast sensitivity threshold for five spatial frequencies (1.5, 3.0, 6.0, 12.0, and 18.0 cycles/degree). RESULTS: All 26 children completed the testing at all five spatial frequency levels with both eyes under monocular testing conditions. The average actual testing time required less than 7.0 minutes for the combined right and left eye test time for all subjects. The results suggest that as the age increased, there was a tendency for an overall increase in the child's ability to detect lower contrast levels. The results indicate that this modified procedure yielded values proximal to adult CSF values, especially in the higher spatial frequencies. CONCLUSIONS: We have demonstrated that a modified forced-choice procedure using Vistech CSF gratings could be used in a preschool population. The two alternative forced choice method used in this study was found to be an effective and clinically efficient technique for evaluating the CSF levels in preschool children and makes it possible to screen for a variety of visual and neurological conditions in the preschool child.

Aging↗
PubMed2000

[Contrast sensitivity after laser in situ keratomileusis for myopia (LASIK-M)].

PURPOSE: To evaluate the effect of laser in situ keratomileusis for the correction of moderate myopia (LASIK) on contrast sensitivity values. METHODS: Seventeen eyes of 10 patients underwent LASIK to correct myopia ranging from 7.75 to -4.75 D (mean +/- SD, -6.53 +/- 0.99 D). Contrast sensitivity was tested preoperatively and 1, 3, 6 and 12 months postoperatively using the CVS -1000 contrast sensitivity test (Vector Vision). RESULTS: Contrast sensitivity decreased in the first postoperative month, the decrease was significant for 6 dg and 12 c/g (P -0.006 and P=0.005, respectively). At 3 months it returned to preoperative values although it was not statistically significant (P>0.05). There was an improvement at 6 months at spatial frequencies of 3 c/g and 6 c/g and at 12 months the improvement was for 3, 6 and 18 c/g, although the changes were not significant. CONCLUSION: Although LASIK decreased contrast sensitivity values at one month after surgery, these values returned to the preoperative levels at 3 months. The improvement at certain frequencies at 6 and 12 months suggests that LASIK can improve the quality of vision in eyes with low to moderate myopia.

Adult↗
PubMed2002

Temporal contrast sensitivity using full-field flicker test (Erlangen flicker test) in patients after penetrating keratoplasty.

BACKGROUND: The purpose of this study was to evaluate the feasibility of temporal contrast sensitivity testing using full-field flicker stimulation in patients after penetrating keratoplasty (PK) and to assess whether this method is influenced by postoperative corneal topographic changes. METHODS: Forty-five patients (age 46.5+/-14.2, median 47 years) who had undergone PK and 194 age-matched controls were included in this study. The postoperative interval was 11.8+/-10.2 months (median 9 months). Patients with pre-existing glaucoma or any postoperative intraocular pressure elevation were excluded. The indications for PK were keratoconus in 54% of cases, Fuchs' dystrophy in 38% and stromal dystrophies in 8%. Temporal contrast sensitivity was determined with sinusoidal flickering light (37.1 Hz) of constant mean photopic luminance (10 cd/m(2)) presented in a full-field bowl with an increasing threshold strategy. RESULTS: Mean temporal contrast sensitivity did not differ between patients after PK (1.49+/-0.13, range 1.26-1.78, confidence interval 1.45-1.53) and controls (1.55+/-0.17, range 1.16-1.98, confidence interval 1.47-1.51). No significant correlation between temporal contrast sensitivity and visual acuity could be found in patients after PK or in normals ( r<0.2, P=0.3). In patients after PK, temporal contrast sensitivity was statistically independent of keratometric astigmatism ( r=0.3, P=0.7), topographic astigmatism ( r=0.3, P=0.4), spherical equivalent ( r=0.07, P=0.7), central corneal thickness ( r=-0.06, P=0.7) and time since operation ( r=-0.07, P=0.6). CONCLUSIONS: Temporal contrast sensitivity using full-field flicker stimulation seems to be feasible in patients after PK and does not depend on topographic changes of the cornea. The results indicate that the full-field flicker test may be helpful as a supplementary means of detecting early glaucoma caused by ocular hypertension in patients after PK.

Adult↗
PubMed2002

[Contrast sensitivity].

This paper presents a few theoretical considerations about the contrast sensitivity, modalities of testing and changes of contrast sensitivity in different ophthalmologic diseases.

Contrast Sensitivity↗
PubMed1984

Contrast sensitivity measurements in acute and resolved optic neuritis.

We measured contrast sensitivity by means of Arden grating plates in 41 eyes with acute optic neuritis and in 51 eyes with resolved optic neuritis. The scores were abnormal in 93% of eyes in the acute phase and 78% in the resolved phase irrespective of visual acuity. Even when acuity improved to 6/7.5 or better with resolution of the neuritis, 67% of eyes still showed abnormal contrast sensitivity. Since Snellen acuity represents just one point at the high spatial frequency end of the contrast sensitivity function, a patient in whom acuity improves to 6/6 with resolution of optic neuritis may still have difficulty seeing objects of lower relative contrast or at lower spatial frequencies.

Acute Disease↗
PubMed2006

The relationship between visual contrast sensitivity and neuropsychological performance in a healthy elderly sample.

Visual acuity and contrast sensitivity are two visual domains affected by normal aging; however, the potential impact of well-documented changes in these abilities on neuropsychological assessment is relatively unstudied. The current study examined the relationship between these abilities and neuropsychological performance in a healthy, community-based elderly sample. Fifty-one individuals (Age: M = 79.6) were assessed for visual acuity and visual contrast sensitivity, and received a brief neuropsychological battery. Results indicated contrast sensitivity was significantly related to neuropsychological performance on visually based measures, but not auditory measures. Visual acuity was only weakly related to neuropsychological performance. Clinical implications for assessment of elderly individuals are discussed.

Aged↗
PubMed2003

Sweep visual evoked potential evaluation of contrast sensitivity in Alzheimer's dementia.

PURPOSE: The purpose of this study was to evaluate primary afferent visual pathway function by objectively testing contrast sensitivity in persons with Alzheimer's dementia (AD), using a sweep visual evoked potential technique. METHODS: Twenty-five patients, 16 with AD and 9 elderly control (EC) subjects, were enrolled from the University of Southern California Rancho Los Amigos Medical Center. The patients with AD had clinical dementia ratings ranging from 0.5 to 3, corresponding to mild to moderate disease. All participants underwent refraction and screening for ophthalmic disease. Subjects were evaluated with the sweep visual evoked potential technique. Each trial consisted of logarithmically increasing contrast over a 10-second period. Subjects were evaluated monocularly at spatial frequencies of 1, 5, and 8 cyc/deg. Patients were not required to integrate and respond to stimuli. RESULTS: Mean contrast sensitivity thresholds were significantly higher in patients with AD than in EC subjects. The mean contrast sensitivities in the AD group were 4.0%, 9.6%, and 18.6%, at 1, 5, and 8 cyc/deg, respectively. The corresponding sensitivities in the EC group were 2.1%, 5.3%, and 11.4%, at 1, 5, and 8 cyc/deg, respectively. These threshold differences were significant at probabilities of 0.01, 0.05, and 0.07. There was no correlation between clinical dementia ratings and reduction of contrast sensitivity thresholds. Confounding factors such as age, gender, nuclear sclerosis, and visual acuity were evaluated. Visual acuity was the only factor significantly different between AD responders and AD nonresponders at 1 and 5 cyc/deg. CONCLUSIONS: These results suggest patients with AD have deficits in contrast sensitivity attributable to dysfunction of the primary afferent visual pathway.

Aged↗
PubMed1986

Correlation between ERG oscillatory potential and psychophysical contrast sensitivity in diabetes.

Correlation between the electroretinographic oscillatory potential and psychophysical contrast sensitivity function was examined in patients with different stages of diabetic retinopathy. Contrast sensitivity function was evaluated by Arden's grating test. The amplitude of the oscillatory potential was significantly reduced in cases with low contrast sensitivity (P less than 0.01).

Diabetes Mellitus, Type 2↗