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PubMed1987

Cigarette smoking, field-dependence and contrast sensitivity.

This study examined the separate and combined effects of cigarette smoking and field-dependence on contrast sensitivity. No previous research on these relationships exists; however, all three variables are known to be significantly related to many aspects of human performance. Under carefully controlled conditions, 12 smokers and 16 non-smokers were tested for field-dependence and measured for contrast sensitivity (Nicolet CS 2000 Testing System). No differences in contrast sensitivity of smokers were found when measured immediately after smoking 1 cigarette, as compared with having been deprived of smoking for at least 90 min. Habitual smoking and field-dependence were found to be separately and interactively related to contrast sensitivity. A field-independent non-smoker group performed significantly better than a field-dependent smoker group at all but the lowest spatial frequency. The results have important implications for many types of performance, particularly aircraft and motor vehicle operation, and may be valuable for use in selection and training.

Adult↗
PubMed1989

Contrast sensitivity and glare sensitivity changes with three types of cataract morphology: are these techniques necessary in a clinical evaluation of cataract?

LogMAR visual acuity, contrast sensitivity and glare sensitivity measurements were made on 39 eyes of 18 cataractous subjects and compared against normative data. Only cataracts of one of the main three morphological cataract types were used--cortical, nuclear and posterior subcapsular. Results indicate that contrast sensitivity decline with cataract is an intermediate and high spatial frequency loss. For nuclear and cortical cataracts with a LogMAR visual acuity of less than 0.5 (Snellen equivalent better than 6/18), there was no loss of contrast sensitivity at the lowest spatial frequency (1 c/deg). For posterior subcapsular cataracts, low spatial frequency contrast sensitivity loss did occur but was unrelated to visual acuity. Glare sensitivity increased for all cataract types. This was related to visual acuity for both cortical and nuclear cataracts but was not for the posterior subcapsular type. It was concluded that contrast and glare sensitivity measurements are a useful part of the assessment of visual function in patients with posterior subcapsular cataract.

Aged↗
PubMed2004

Contrast sensitivity after implantation of toric iris-claw lenses in phakic eyes.

PURPOSE: To evaluate the change in contrast sensitivity after implantation of the Verisyse toric phakic intraocular lens (IOL) (AMO) for the correction of myopia with astigmatism. SETTING: Department of Ophthalmology, Johannes Gutenberg-University, Mainz, Germany. METHODS: Eighteen eyes had implantation of an iris-supported toric phakic IOL to correct myopia with astigmatism. The mean preoperative spherical equivalent was -12.65 diopters +/- 3.6 (SD). The contrast sensitivity with best spectacle correction was determined before surgery and 3 months after surgery using the CSV-1000 HGT instrument (Vector Vision Inc.). RESULTS: Three months after IOL implantation, the mean contrast sensitivity had significantly increased from preoperatively at midrange spatial frequencies from 3.2 to 4.4 (6 cycles per degree [cpd]; P = .033) and from 2.4 to 3.7 (12 cpd; P = .032). The differences at spatial frequencies of 3 cpd and 18 cpd were not statistically significant (P = .59 and P = .086, respectively). CONCLUSIONS: Implantation of the Verisyse toric iris-claw lens in phakic eyes to correct high or moderate myopia with astigmatism has the potential to improve contrast vision. The mean contrast sensitivity increased considerably at all spatial frequencies compared with preoperative levels.

Adult↗
PubMed1984

Spatial contrast sensitivity. Importance of controlling the patient's visibility criterion.

Clinical spatial contrast sensitivity measurements are typically made using psychophysical methods that do not specify the response criterion being used by the patient in judging grating visibility. Results of this report show the necessity of such methods for (1) maximizing detectability of early contrast sensitivity deficits by minimizing normal sample variance, and (2) ensuring that changes in an individual's contrast sensitivity reflect changes in vision and not simply fluctuations in the patient's criterion for judging grating visibility.

Adult↗
PubMed1996

Spatial frequency dependent observer bias in the measurement of contrast sensitivity.

A previously reported spatial frequency dependent change in contrast sensitivity, apparently produced by the psychometric method used, was investigated in two experiments. A relative reduction in the measured contrast sensitivity function at higher spatial frequencies was found when using a simple single staircase procedure, even when all external characteristics of the presentation procedure were the same as a more sophisticated and more reliable psychometric method (adaptive probit estimation). The estimated false-negative response rate was found to be greater for the single staircase procedure and was greater at a higher spatial frequency, while the false-positive response rate to interleaved blank presentations did not vary between spatial frequencies and between the two psychometric methods. This supports the suggestion that some subjects, given a knowledge of the psychometric method controlling grating contrast, may adopt different decision criteria at different spatial frequencies.

Adult↗
PubMed1990

Pindolol and timolol: short-term influence on angioscotomas and static brightness contrast sensitivity.

In a double-masked, short-term study on 12 healthy elderly volunteers, angioscotomas and contrast sensitivities were measured 2 h after treatment with placebo, pindolol 1% and timolol 0.5%. In perimetry, angioscotomas did neither change in deepness nor in diameter significantly. However, the mean differential light sensitivity was highest with timolol (15.5 dB) and lower with pindolol (15.2 dB p less than 0.018) and placebo (15.0 dB; p less than 0.004). In contrast sensitivity testings, the mean contrast sensitivity was lowest with timolol (15.0 dB) and higher with pindolol (15.3 dB p less than 0.001) and placebo (15.7 dB; p less than 0.001). The differences between pindolol and placebo were not significant in both tests. The contrasting results may be explained by the locations where retinal sensitivity was tested, near or far from retinal vessels i.e. foveally or near the blind spot. Pharmacologically, the main difference between the two medications is the intrinsic sympathomimetic activity of pindolol.

Aged↗
PubMed1992

The effect of early cataracts on glare and contrast sensitivity. A pilot study.

To establish the effect of cataracts on glare and contrast sensitivity, we graded type and amount of lens opacity in 110 subjects who underwent two glare tests (Brightness Acuity Tester and Berkeley glare test) and two contrast sensitivity tests (a sine-wave test and Pelli-Robson chart). Twenty-seven subjects (25%) had clear lenses (mean visual acuity of 20/20) and 83 subjects (75%) had early lens opacities (mean visual acuity of 20/40) in otherwise normal eyes. Multiple regression techniques were used to control for the effects of age and visual acuity. Glare test scores were significantly lower for nearly all patients with lens opacities than for patients with clear lenses and were the lowest for patients with lenses with posterior subcapsular opacity. Contrast sensitivity scores were lower for all patients with lens opacities than for patients with clear lenses at high frequencies only; all lens opacity groups scores similarly with each other. These results indicate reduced visual function among patients with cataracts whose visual acuity is only minimally impaired.

Cataract↗
PubMed1985

Central contrast sensitivity tests in the detection of early glaucoma.

The value of contrast sensitivity testing in glaucoma is still unsettled. To determine their value in screening for glaucoma 2 methods were applied to glaucoma patients (12 simplex, 9 pseudo-exfoliative). The techniques included an oscilloscope method generating centrally presented gratings and the Arden grating test. Results obtained were compared to those of age-matched normals (n = 11, one eye randomly selected). Unacceptable false negative rates were found for both methods, as well as a high false positive rate (2/11 normals) with the Arden grating test, confirming findings in earlier studies. No correlation could be demonstrated between contrast sensitivity deficits and visual field disturbance, glaucoma type or duration. It was concluded that central contrast sensitivity for static gratings is unable to reliably indicate the presence or absence of early glaucoma.

Aged↗
PubMed1981

Abnormal adaptation of visual contrast sensitivity in multiple sclerosis patients.

Some multiple sclerosis patients with 20/20 acuity complain of poor vision. In a previous report we accounted for this in our patient group by showing that multiple sclerosis had caused a depression of contrast sensitivity while sparing visual acuity. In this study we investigated whether some of this measured depression might be due to abnormally rapid or severe adaptation during the test procedure rather than a true permanent loss. Our finding was opposite to this supposition: adaptation was normally slight and/or slow. Depressed contrast sensitivity was not well correlated with abnormal adaptation to contrast. In patients whose contrast sensitivity losses were restricted to a band of spatial frequencies, we found no evidence that abnormalities of contrast adaptation were restricted to this same spatial frequency band. Further evidence of dissociation between abnormal contrast sensitivity and abnormal contrast adaptation is that some patients with normal contrast sensitivity showed abnormally small adaptation.

Adaptation, Ocular↗
PubMed1998

Effects of moderate blood alcohol concentrations on spatial and temporal contrast sensitivity.

OBJECTIVE: In order to gain a more complete picture of the influence of alcohol on visual performance, we measured contrast sensitivity for a range of spatial and temporal frequencies in individuals with moderate blood alcohol concentrations (BACs). METHOD: Subjects were tested at blood alcohol concentrations of 0.06% in both the rising and falling phases of absorption. In the first part of the study, the performance of two men and four women on a number of simple screening measures and static contrast sensitivity was measured. In the second part (four men and three women), the grating patterns were contrast reversed at four different rates, allowing us to assess the effects of alcohol on temporal processing. The second study examined the relationship between blood alcohol concentrations and contrast sensitivity. RESULTS: Although few significant changes in performance were found on the simple screening tests, we observed a significant reduction (43%) in stationary contrast sensitivity at the 0.06% BAC. This change in performance was greater at low and high spatial frequencies than at moderate ones. At high temporal frequencies, the reduction in sensitivity was 2.5 times that seen for lower temporal frequencies. With higher blood alcohol concentrations, the decrease in performance was found to be greatest for the high and low spatial frequencies. CONCLUSIONS: These data suggest that alcohol produces visual deficits that are not attributable to pursuit eye movements. It is suggested that these visual deficits, combined with changes in ocular-motor control and attentional deficits, may have a strong effect on performance under the influence of alcohol.

Adult↗
PubMed1998

Peripheral and central colour contrast sensitivity in diabetes.

PURPOSE: To study the influence of diabetes, with or without early retinopathy, on peripheral and central colour contrast sensitivity. METHODS: The study included 32 patients with diabetes mellitus type II and 47 age-matched normals. The patients were divided into three sub-groups. 1. Diabetics with no retinopathy (on photographs or biomicroscopy). 2. Diabetics with microaneurysms only. 3. Diabetics with microaneurysms and hard exudates. Colour contrast sensitivity was measured with a computer graphics system along the protan, deutan and tritan axes. RESULTS: The peripheral colour contrast thresholds were significantly elevated for all axes when comparing the group with microaneurysms and exudates to normals. There were also significant differences between the group with microaneurysms and hard exudates and the two other diabetic groups, respectively, but only for the tritan axis. Diabetics with no retinopathy or with microaneurysms only did not differ significantly from normals. The central colour contrast thresholds showed significant differences between normals and the group with microaneurysms, but only for the protan and deutan axes. There were significant differences for all three axes between normals and the group with microaneurysms and hard exudates. There were also significant differences between the group with microaneurysms and hard exudates and the two other diabetic groups, but only for the tritan axis. Diabetics with no retinopathy did not differ significantly from normals. CONCLUSION: Peripheral colour contrast sensitivity was affected by low-grade diabetes type II retinopathy. This finding has to be considered if the method is to be used in screening for glaucoma. The central colour contrast sensitivity test seems to correlate to the degree of retinopathy and thereby perhaps provides a new screening method for diabetes retinopathy. Further studies are required in order to evaluate such a possibility.

Aged↗
PubMed1989

Contrast sensitivity in multiple sclerosis measured by Cambridge Low Contrast Gratings: a useful clinical test?

The Cambridge Low Contrast Gratings (CLCG) were used to assess contrast sensitivity (CS) in 39 patients with clinically definite multiple sclerosis and 60 control subjects. CS was determined in both horizontal and vertical orientations and compared with visual evoked responses (VERs) in the same populations. Only 33% of patients had abnormal CS whereas 82% had abnormal VERs. There was no correlation between the degree of abnormalities in CS and VERs. There was no significant difference between CS determined in the vertical and horizontal orientation; however, examination in the vertical orientation increased the number of abnormalities detected by 2 (5%). We conclude that although CS, using the CLCG, is abnormal in a proportion of multiple sclerosis patients its detection is not clinically useful and is insensitive as a measure of subclinical optic neuropathy in multiple sclerosis.

Adult↗
PubMedDate not supplied

Impact of contrast sensitivity performance on visually presented neurobehavioral tests in mercury-exposed children.

Presentation of neuropsychological tests on a computer screen may involve a visual challenge to the examinee. The possible need for adjustment for visual contrast sensitivity on test performance was therefore determined from data on 917 mercury-exposed children who were examined at age 7 years. Contrast sensitivity was found to be associated with performance on the computer-assisted Continuous Performance Test. However, it showed similar associations with performance on traditional pencil-and-paper tests, especially Bender Visual Motor Gestalt Test and Wechsler Intelligence Scale for Children-Revised (WISC-R) Block Designs. Contrast sensitivity was not associated with prenatal mercury exposure, and adjustment for visual function had only a negligible effect on the regression coefficients for mercury as predictor of neuropsychological deficits. The mercury-associated neurobehavioral deficits are therefore unlikely to be due to mercury-induced visual system dysfunction causing secondary deficits in cognitive domain testing. Visuospatial processing appears to be a determinant in contrast sensitivity performance, and careful consideration of whether to control for contrast sensitivity in future studies of neurotoxicant effects is therefore recommended.

Bender-Gestalt Test↗
PubMed2003

The effect of peripheral visual motion on focal contrast sensitivity in positive- and negative-symptom schizophrenia.

The aim of the present research was to investigate the effect of peripheral (ambient) stimulation on focal visual processing using the far-out jerk effect in normal observers and subgroups with positive- and negative-symptoms in schizophrenia. The far-out jerk effect refers to a reduction in sensitivity of a briefly presented stimulus in central vision in the presence of a sudden movement or oscillation of a stimulus in peripheral vision. In order to measure the far-out jerk effect the focal contrast sensitivity of 5.0Hz modulated sinusoidal target gratings (0.5, 1.0, 2.0, 4.0, and 8.0 number of cycles per degree (c/degrees )) was measured in the presence of three kinds of peripheral surround: a blank field, a stationary 0.75 c/degrees grating, and a 5.0Hz drifting 0.75 c/degrees grating (far-out jerk effect). The findings showed that there were no significant differences in focal contrast sensitivity between the control and positive-symptom group with a blank field and stationary grating surround. However, a 5.0Hz drifting grating surround resulted in a significant reduction in contrast sensitivity at 0.5, 1.0 and 2.0 c/degrees in the positive-symptom group. In comparison with the control group the negative-symptom group showed a generalised reduction in focal contrast sensitivity, a significantly smaller far-out jerk effect, and a significant reduction in contrast sensitivity at 0.5 c/degrees with a stationary grating surround. The finding that both stationary and moving peripheral surrounds have an inhibitory effect on focal contrast sensitivity suggests that there is a dispersion in the visual demarcation between stationary and temporal events in the perception of visual motion in the negative-symptom group.

Adult↗
PubMed2003

Effect of intraocular lens implantation on visual acuity, contrast sensitivity, and depth of focus.

PURPOSE: To determine the role of spherical and irregular aberrations in the optics of the natural eye and after intraocular lens (IOL) implantation in terms of visual acuity, contrast sensitivity, and depth of focus. SETTING: Laboratory of Experimental Ophthalmology, University of Groningen, Groningen, The Netherlands. METHODS: Visual acuity and defocus-specific contrast sensitivity in 11 pseudophakic patients (IOL group) and 27 age-matched phakic subjects were compared. The results were obtained psychophysically. Spherical and irregular aberrations were subsequently estimated by comparing the measured myopic shift (optimum focus of contrast sensitivity at 4 cycles per degree [cpd] compared to that at 16 cpd) and depth of focus with those of theoretical eye models with varying amounts of irregular and spherical aberrations. RESULTS: The best corrected visual acuity and best corrected contrast sensitivity in the IOL group did not significantly differ from that in the phakic group. The depth of focus was larger in the IOL group at a pupil diameter of 6.0 mm (P<.05). Comparison with theoretical eye models suggested a higher amount of spherical aberration in the IOL group; irregular aberration was almost the same in both groups. CONCLUSIONS: There was a higher amount of spherical aberration in the IOL group, related to a larger depth of focus, without loss of contrast sensitivity at optimum focus or loss of visual acuity. This might contribute to better quality of vision in pseudophakic subjects than in presbyopic phakic subjects.

Contrast Sensitivity↗
PubMed1987

Use of contrast sensitivity measurement in the detection of subclinical ethambutol toxic optic neuropathy.

Contrast sensitivity was measured by means of Arden grating plates in 100 patients on medication for pulmonary tuberculosis. The scores were abnormal in 38.2% of the patients whose therapy included ethambutol for three months, and 36.7% of the patients on similar treatment for six months. In comparison with age matched groups of patients on a regimen where streptomycin replaced ethambutol a statistically significant number of the patients on ethambutol had abnormal scores. This study suggests that Arden contrast sensitivity plates would be effective in detecting subclinical toxic optic neuropathy due to ethambutol and therefore could be used for routine monitoring of ocular function of patients on ethambutol. Loss of contrast sensitivity may explain why some patients on ethambutol with normal visual acuity and colour perception may still complain of visual disturbance.

Adult↗
PubMed2000

Veterans Affairs Multicenter Low Vision Enhancement System (LVES) study: clinical results. Report 1: effects of manual-focus LVES on visual acuity and contrast sensitivity.

PURPOSE: The Department of Veterans Affairs LVES Study is a multicenter study to determine the effectiveness of the Low Vision Enhancement System (LVES) as a visual rehabilitation device. The purpose of this study was to explore the efficacy of the Beta 1 manual-focus LVES for improving visual acuity and contrast sensitivity. METHODS: Patients whose visual acuity was 20/80 or worse in the better eye from any disease, who did not have significant visual field loss, who had previous low vision experience and were capable of working with the LVES were enrolled in a comprehensive prospective multicenter clinical evaluation. Initially, corrected spectacle visual acuities were measured using a standardized ETDRS chart. Contrast sensitivities were also measured with spectacle correction using a standardized Peli-Robson chart. These results were then compared to the acuities and contrast sensitivity obtained with the LVES at optimal magnification. Also, visual acuities were measured using an Eschenbach 3x spectacle-mounted binocular telescope, then compared to the acuities obtained using the LVES set at the lowest magnification (3x). RESULTS: All patients who completed the study demonstrated an improvement in visual acuity, with a median improvement of six lines of Snellen equivalent acuity using the LVES. Improvement in visual acuity was the same in both ARMD and non-ARMD causes of vision loss. Mean contrast sensitivity improved in 52 of 58 patients tested, with a mean improvement of 0.49 log units. CONCLUSION: The LVES significantly improves both visual acuity and contrast sensitivity in visually impaired patients who fall within the study criteria. Up to 10-fold improvement in visual acuity and up to 1.80 log units improvement in contrast sensitivity were noted in the study group when the LVES was used.

Adult↗
PubMed1981

A pilot study of contrast sensitivity assessment of the CAM treatment of amblyopia.

Contrast thresholds of varying spatial frequencies were obtained on 3 amblyopic patients before and after the CAM treatment of amblyopia. Results of this study confirm previous findings that in the absence of change of visual acuity, contrast sensitivity function can be changed with the use of this technique. Improvement of contrast sensitivity can occur in older patients and that the sensitivity sometimes can deteriorate when treatment is stopped.

Amblyopia↗