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PubMedDate not supplied

Observations on the use of three different contrast sensitivity tests in children and young adults.

Forty-one children and young adults aged 4 to 25 years (mean 14.5 +/- 6.9, SD) with normal eyes were examined with three different contrast sensitivity tests: the Vistech distance and near test, the Cambridge Low Contrast Gratings test, and the LH-5 Contrast test. In different age groups, the youngest children aged 4 to 9 years had the lowest result values. The results of the older children aged 10 to 15 years and young adults aged 16 to 25 years were close to each other. The range of the results in all tests was large in every age group. The values of contrast sensitivity could not be compared from one test to another; in the Vistech tests the values varied from 10 to 200, in the Cambridge test from 170 to 560, and in the LH-5 test from 5 to 50. Most of the children liked the LH-5 test best, while most of the young adults preferred the Vistech distance test. It is useful to examine children and adults with different contrast sensitivity tests; however, the same test should be used in follow-up examinations.

Adolescent↗
PubMed1997

The validity of current clinical tests of contrast sensitivity and their ability to predict reading speed in low vision.

PURPOSE: Contrast sensitivity (CS) testing using chart tests of CS is becoming increasingly common in low vision assessment. Yet we know little about the validity of these charts, i.e. which region of the spatial frequency spectrum is being measured. In this study we aimed to determine the validity of currently available CS charts by comparison against oscilloscope-based CS. We also determined their relative ability to predict reading speed. METHODS: CS was measured with five commercially available charts and the contrast sensitivity function was determined with sinusoidal gratings presented on a Joyce screen using a two-alternative forced choice staircase technique in 36 observers with low vision and 3 with normal vision. Reading rate was also measured with the subject reading with his or her own optical low vision aid. RESULTS: The results show that the Pelli-Robson chart and the Cambridge gratings are good measures of medium to low spatial frequencies, as would be predicted from their design, while the Regan and UW charts correlated with medium to high frequencies. The Vistech chart was a good predictor of CS at each spatial frequency. CONCLUSIONS: The best chart test of CS depends on which region of the CS curve is of interest. All the charts were good predictors of reading rate.

Adult↗
PubMed1993

Contrast sensitivity and visual acuity in patients with early cataracts.

In a population of 188 nondiabetic patients with early cataracts or nuclear brunescence, we assessed the degree to which contrast sensitivity function (CSF) provided more information about a patient's visual disability than high contrast visual acuity measurements. Data collected included LOCS II cataract classification, Bailey-Lovie visual acuity (LogMAR score), Lotmar interferometric visual acuity (LI VA), and distance contrast sensitivity function (CSF) using the Vistech 6500. Generalized least squares regression models in which CS was the dependent variable and either LogMAR score or LI VA was among the independent variables were used to ascertain whether CSF provided additional information about visual disability to that provided by LogMAR score or LI VA. Contrast sensitivity function was decreased only by nuclear opalescence at high frequencies (12 to 18 cpd); for all other cataract types and nuclear color, CSF testing provided no more information about cataract-related visual loss than LI VA or LogMAR score. Measurement of CSF using the Vistech 6500 system in patients with early cataracts provides information on visual dysfunction beyond that provided by LogMAR score or LI VA only in patients with nuclear opalescence, and that may not be clinically significant.

Adult↗
PubMed2002

Contrast sensitivity and the Stiles--Crawford effect.

We investigated the influence of the Stiles-Crawford effect (SCE) of the first kind on the contrast sensitivity function using the apodisation model of the SCE. The SCE was measured for the right eyes of two subjects using an increment threshold technique involving a two-channel Maxwellian-viewing system. Filters made of photographic film neutralised or doubled the SCE. Contrast sensitivities were measured with a 6 mm pupil diameter, defocus to +/-2D, and three SCE conditions (normal, neutralised and doubled). Modulation transfer functions were derived after measuring transverse aberrations with a vernier alignment technique, and were used to predict contrast sensitivity functions (CSFs). The measured CSFs were, in general, reasonable matches with the predicted CSFs. In particular, both demonstrated definite undulations ("notches") as defocus level increased. The influences of the SCE-modifying filters were generally of similar magnitude and direction to predictions, thus supporting the apodisation model of the SCE. The magnitudes of SCE influence between SCE-neutralised and SCE-doubled conditions were usually small at about 0.2-0.3 log unit, with a maximum influence of 0.5 log unit. Influences of the SCE were greater for myopic than for hypermetropic defocus. As measured by the CSF and an apodisation model, this study is in agreement with previous theoretical work and one experimental study in indicating that the SCE plays a minor role in improving spatial visual performance.

Contrast Sensitivity↗
PubMedDate not supplied

Contrast sensitivity in extended wear of the Boston IV lens.

Over a one-year period we evaluated subjective and objective factors associated with extended wear of Boston IV rigid gas permeable contact lenses. Patients wore the lens on an extended wear schedule, with removal at 2-week intervals for cleaning. We performed keratometry and endothelial cell counts and measured visual acuity, contrast sensitivity, refraction, and corneal thickness at the initial visit (with patients wearing their former glasses or soft or hard lenses) and again at 6 and 12 months (with patients wearing the Boston IV lens). Twenty-four of 31 patients (77%) completed the study. All measured parameters were checked for statistically significant change over time. Contrast sensitivity increased at all spatial frequencies tested, with the largest increments occurring at higher frequencies (P less than .001). The other parameters showed no significant changes (P greater than .05). Our data support the use of contrast sensitivity for qualitative assessment of visual function among contact lens wearers and suggest that contrast sensitivity testing may prove to be a more effective means of evaluating visual acuity in contact lens wearers over time than Snellen acuity.

Cell Count↗
PubMed2006

Retrobulbar haemodynamics and contrast sensitivity improvements after CO2 breathing.

PURPOSE: Effects of gas mixtures have been widely studied. Carbon dioxide (CO(2)) is known to act as a vasodilator, whereas oxygen (O(2)) acts as a vasoconstrictor. Therefore, the interpretation of results is difficult. In this study, only the effect of an elevated CO(2) level on retrobulbar hemodynamics and contrast sensitivity was investigated. METHODS: Thirty adults (age 31 +/- 7) were examined under normocapnic and hypercapnic conditions. Colour Doppler imaging was used to measure the velocity in the ophthalmic and central retinal artery. Moreover, contrast sensitivity using the CSV-1000 was investigated. Blood pressure, heart rate and intraocular pressure (IOP) were measured and ocular perfusion was calculated. RESULTS: Under hypercapnia, mean end tidal CO(2) increased from 36.4 mmHg to 42.5 mmHg and blood oxygen saturation increased from 98.3% to 98.6% (p < 0.0001). Hypercapnia significantly reduced IOP by 0.94 mmHg (p < 0.0008). In the central retinal artery, the mean PSV increased by 18% (p < 0.0001) and the mean EDV by 21% (p = 0.0054). In the ophthalmic artery, the mean PSV increased by 13% (p < 0.0001) and the mean EDV by 26% (p = 0.0002). Furthermore, there was a significant increase of contrast sensitivity (spatial frequency: 3cpd: p = 0.0016; 6cpd: p = 0.005; 12cpd: p = 0.0012). Systolic blood pressure (p = 0.0225), mean arterial blood pressure (p = 0.0097) and ocular perfusion pressure (p = 0.0013) increased significantly. CONCLUSION: This setting was able to detect an increase in blood flow velocity in normal subjects under hypercapnia. Furthermore, hypercapnia results in a functional improvement in contrast sensitivity, possible due to the increased blood flow or the increase in blood oxygen levels.

Adult↗
PubMed1990

Survey of the clinical use of glare and contrast sensitivity testing.

In August 1988, we surveyed a random 10% sample of the members of the American Society of Cataract and Refractive Surgery about their use of contrast sensitivity and glare testing. Of 396 surveys mailed, 214 were returned for a response rate of 54.3%. Thirty-six percent of respondents used glare testing alone; 5.6% used contrast sensitivity testing alone; 23.4% used both test modalities; 35% used neither. The most common uses of glare and contrast sensitivity testing were to evaluate visual function in patients who have cataracts, secondary cataracts, and/or intraocular lens problems.

Cataract↗
PubMed2005

The pointillism method for creating stimuli suitable for use in computer-based visual contrast sensitivity testing.

An increasingly large corpus of clinical and experimental neuropsychological research has demonstrated the utility of measuring visual contrast sensitivity. Unfortunately, existing means of measuring contrast sensitivity can be prohibitively expensive, difficult to standardize, or lack reliability. Additionally, most existing tests do not allow full control over important characteristics, such as off-angle rotations, waveform, contrast, and spatial frequency. Ideally, researchers could manipulate characteristics and display stimuli in a computerized task designed to meet experimental needs. Thus far, 256-bit color limitation in standard cathode ray tube (CRT) monitors has been preclusive. To this end, the pointillism method (PM) was developed. Using MATLAB software, stimuli are created based on both mathematical and stochastic components, such that differences in regional luminance values of the gradient field closely approximate the desired contrast. This paper describes the method and examines its performance in sine and square-wave image sets from a range of contrast values. Results suggest the utility of the method for most experimental applications. Weaknesses in the current version, the need for validation and reliability studies, and considerations regarding applications are discussed. Syntax for the program is provided in an appendix, and a version of the program independent of MATLAB is available from the author.

Computer Graphics↗
PubMed1994

Age-related effects of glare on luminance and color contrast sensitivity.

PURPOSE: To determine the effect of disability glare (DG) upon luminance and color contrast sensitivity for young and elderly subjects. METHODS: DG was defined as the difference in contrast sensitivity with and without the presence of a glare source. Isoluminant color gratings were modulated either along a red-green (R-G) or blue-yellow (B-Y) axis. RESULTS: Without glare the effect of age on sensitivity to both luminance and R-G color-modulated gratings was small and did not reach statistical significance (P > 0.1). However, the reduction in sensitivity for B-Y color modulation was highly significant (P < 0.01). For both age groups, DG was greatest for the R-G stimulus and least for the B-Y. DG in the elderly increased relative to the young observers for both R-G and luminance-modulated gratings (P < 0.01) but not for B-Y (P > 0.01). CONCLUSIONS: The precise effect of a glare source on color discrimination depends upon a complex interaction between the chromaticity of the glare source and that of the stimulus. In certain circumstances, such as in our R-G stimulus, glare can dramatically reduce chromatic discrimination ability by desaturating the component colors.

Adult↗
PubMed1986

Contrast sensitivity testing in pseudotumor cerebri.

Twelve patients with pseudotumor cerebri underwent sensory visual testing and the results were analyzed. Contrast sensitivity loss was detected with use of Arden gratings in nine of the twelve patients (75%) and in 13 of 24 eyes (54%). Snellen acuity was worse than 20/20 in 21% of eyes. Contrast sensitivity scores improved with resolution of the patient's papilledema whereas there was no significant improvement of Snellen acuity. Contrast sensitivity testing with Arden plates is a useful procedure for detecting visual loss and serially following patients with pseudotumor cerebri.

Adult↗
PubMedDate not supplied

Contrast sensitivity and the diagnosis dysthyroid optic neuropathy.

Contrast sensitivity function (CSF) was investigated in 19 patients (34 eyes) with clinical signs and symptoms of dysthyroid optic neuropathy (DON). CSF was disturbed in 33 eyes and was shown to improve after orbital decompression. These results indicate that the CSF may be a useful supplementary test of visual function in patients with DON.

Adult↗
PubMed2001

Contrast sensitivity and depth of focus with aspheric multifocal versus conventional monofocal intraocular lens.

BACKGROUND: Laboratoires Domilens, Lyon, France, has introduced a new aspheric multifocal intraocular lens (IOL), the Progress 3. The central portion, measuring 4.7 mm in diameter, has an anterior surface of progressively increasing power, such that there is a central add of +5.00 dioptres. We compared contrast sensitivity and depth of focus in patients who received the Progress 3 and in those who received a conventional monofocal IOL. METHODS: Prospective study. Forty patients with age-related cataract were randomly divided into two groups: 20 patients received the Progress 3 aspheric multifocal IOL, and 20 patients received a conventional monofocal IOL of similar design. Contrast sensitivity was measured with the Pelli-Robson letter-based chart. Depth of focus was determined by dialling a series of overcorrections over the patient's manifest refraction until the patient read 6/12 clearly. The depth of focus was defined as the range over which 6/12 or better acuity was achieved. Quality of vision was evaluated by patient questionnaire. RESULTS: Mean contrast sensitivity was significantly lower in the patients with a multifocal IOL than in those with a monofocal IOL (1.38 vs. 1.56 log units) (p < 0.001). The mean depth of focus values for the two groups were 3.10 D and 1.65 D respectively (p < 0.001). The prevalence of subjective problems was similar in the two groups. INTERPRETATION: In our opinion, aspheric multifocal IOLs should be reserved for patients who are willing to trade increased depth of focus for reduced contrast sensitivity postoperatively.

Cataract Extraction↗
PubMed1981

Contrast sensitivity in retinitis pigmentosa.

Arden gratings were used to measure contrast sensitivity in 40 patients with retinitis pigmentosa whose Snellen visual acuity was 6/12 or better. When compared with a group of 30 normal subjects the patients with retinitis pigmentosa had substantially decreased contrast sensitivity, especially at high frequencies. The Arden grating test appeared to be a sensitive test of abnormal central visual function in patients with retinitis pigmentosa.

Adolescent↗
PubMed1987

Adult age differences in visual acuity, stereopsis, and contrast sensitivity.

We investigated adult age differences in four measures of visual function: distance acuity, near acuity, stereopsis, and contrast sensitivity. Twenty-four young adults (mean age 19.5 years) and 24 older adults (mean age 68.4 years) participated. Age differences were present in each of the four measures. A stepwise discriminant analysis performed on the four measures revealed that, when the correlations among the measures were taken into account, only contrast sensitivity significantly discriminated young and older adults' performance. The strength of the correlations among the four measures was greater for older adults than for young adults. The results indicated that contrast sensitivity is a useful measure for detecting age-related changes in visual function and that a common mechanism may underlie age differences on various visual tests.

Adolescent↗
PubMed1982

Contrast sensitivity in children.

We have used a spatial two-alternative, forced-choice staircase technique to measure contrast sensitivities for sinusoidally modulated gratings. Subjects, all of whom were untrained observers, consisted of children of ages 2-16 yr and adults. Our testing method was completely successful with children who were over 3.5 yr but failed with those below 2.5 yr. Mean contrast sensitivities of the youngest group from which data were obtained (2.5-4.5 yr) were 0.35 log units lower than those of adults. However, there was very little difference between these two groups in the middle range of spatial frequencies tested. A gradual increase with age of contrast sensitivities was found up to about 8 yr. This change is probably due to a combination of neural development and non-visual factors.

Adolescent↗
PubMed1990

[Contrast sensitivity in open-angle glaucoma].

The contrast sensitivity function (CSF) was determined with vertical stationary sinusoidal gratings of 6 spatial frequencies of 0.5, 1, 3, 6, 11.4 and 22.8 cycles/degree in 31 patients (50 eyes) with open-angle glaucoma. The data of CSF were compared with visual acuity and visual field determinations. It was found that CSF could be abnormal in subjects with visual acuities of 1.0 or better and normal visual fields; the patterns of CSF loss were varied, and there was a linear correlation between the area of the visual field and the CSF value. The results suggested that the measurement of CSF provided basis for the judgment of visual functional changes in the clinical observation of glaucoma.

Adolescent↗
PubMed2004

Influence of surround illumination on pupil size and contrast sensitivity.

Lighting plays a major role in contrast sensitivity (CS) measurements. Both the test and surround illumination influence the results although they are not usually considered in clinical practice. The effects of test luminance are well known, but the influence of surround luminance seems to be less investigated. This study aims to evaluate the differences in CS measured with two configurations of surround illumination typical of clinical practice; and to analyse the influence of the angular size of the target on pupil diameter for both surround luminances. An experimental arrangement was designed to measure CS with controlled illumination of both test and surround. An infrared pupillometer was also used to measure steady pupil size. A statistically significant increase of CS and a decrease of pupil size with higher surround illumination were found.

Adult↗
PubMed1993

Color, contrast sensitivity, and the cone mosaic.

This paper evaluates the role of various stages in the human visual system in the detection of spatial patterns. Contrast sensitivity measurements were made for interference fringe stimuli in three directions in color space with a psychophysical technique that avoided blurring by the eye's optics including chromatic aberration. These measurements were compared with the performance of an ideal observer that incorporated optical factors, such as photon catch in the cone mosaic, that influence the detection of interference fringes. The comparison of human and ideal observer performance showed that neural factors influence the shape as well as the height of the foveal contrast sensitivity function for all color directions, including those that involve luminance modulation. Furthermore, when optical factors are taken into account, the neural visual system has the same contrast sensitivity for isoluminant stimuli seen by the middle-wavelength-sensitive (M) and long-wavelength-sensitive (L) cones and isoluminant stimuli seen by the short-wavelength-sensitive (S) cones. Though the cone submosaics that feed these chromatic mechanisms have very different spatial properties, the later neural stages apparently have similar spatial properties. Finally, we review the evidence that cone sampling can produce aliasing distortion for gratings with spatial frequencies exceeding the resolution limit. Aliasing can be observed with gratings modulated in any of the three directions in color space we used. We discuss mechanisms that prevent aliasing in most ordinary viewing conditions.

Color Perception↗