SEARCH · Search PubMed

Results for “Contrast Sensitivity”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 487 records · Page 27Linked to original sources

PubMed1993

Spatial contrast sensitivity through aviator's night vision imaging system.

Visual acuity is often used to assess vision through image intensifying devices such as night vision goggles (NVG's). Fewer attempts have been made to measure contrast sensitivity through NVG's. Such information would be useful to better understand contrast processing through NVG's under various stimulus conditions. In this study, computer-generated letter charts were used to measure contrast sensitivity through third generation NVG's for a range of letter sizes. The red phosphor of a standard color monitor proved to be an effective stimulus for third generation devices. Different night sky conditions were simulated over a 3 log unit range. The results illustrate the profile of contrast sensitivity through third generation NVG's over a range of night sky conditions. Comparison of measurements through NVG's to measurements obtained without the device but at the same luminance and color distinguish between effects of luminance and noise on contrast sensitivity.

Adult↗

PubMed2004

Ocular dominance column width and contrast sensitivity in monkeys reared with strabismus or anisometropia.

PURPOSE: To study the relationship between the width of ocular dominance columns in primary visual cortex and spatial contrast sensitivity functions in monkeys with strabismus or anisometropia during infancy. METHODS: Adult monkeys having had monocular visual abnormalities induced in infancy were tested behaviorally for spatial contrast sensitivity and then subjected to functional enucleation of one eye to reveal the ocular dominance columns (ODCs) of the primary visual cortex by cytochrome oxidase (CO) staining. The relative widths of the left and right eyes' ODCs were measured and related to the contrast sensitivity functions. RESULTS: The relative widths of the ODCs having input from eyes with strabismic or anisometropic amblyopia were reduced in proportion to the age of onset and the duration of the early visual abnormality. The relative losses in contrast sensitivity were in ordinal agreement with the losses in relative width of the ODCs. CONCLUSIONS: Amblyopia induced by the early monocular abnormalities of strabismus or anisometropia is proportional to the loss in cortical afference as reflected in the reduction in width of the respective ODCs in the primary visual cortex.

Amblyopia↗

PubMed1996

Evaluation of a new E-optotype chart for measuring contrast sensitivity.

BACKGROUND: Clinical examinations of the contrast sensitivity (CS) are currently made by one-trial measurements of a restricted number of spatial frequencies around the peak of the CS function (CSF). These methods do not allow calculation of the confidence intervals of the single measurements, thus preventing examiners from evaluating the reliability of their data. We elaborated a new method of CS measurement at the peak of the CSF, aiming at economical clinical applicability together with enhanced reliability. Moreover, we tried to establish lower limits of normal CS that would allow classification of low test results as pathological. METHODS: A chart containing six columns of E optotypes of constant size and decreasing contrast (from about 16% to 0.5%) was used to perform six-fold contrast threshold determination (method of descending limits, forced choice). Optotype dimensions are intended to measure the CS at spatial frequencies corresponding to 3 and 6 cycles per degree (c/deg). The reference values were defined by testing 61 normal subjects: 31 "young" (16-35 years) and 30 "old" (56-81 years). RESULTS: The mean logCS found in the young group was 2.07 +/- 0.086 SD for 3 c/deg and 1.94 +/- 0.154 SD for 6 c/deg, while in the old group the mean logCS was 1.88 +/- 0.095 SD and 1.74 +/- 0.118 SD respectively. CONCLUSION: This simple method of measuring CS can provide a single CS value together with a confidence interval for the individual patient, thus allowing evaluation of measurement reliability.

Adolescent↗

PubMedDate not supplied

Visual contrast sensitivity deficits in Bohemian children.

Visual contrast sensitivity (VCS) tests have been used successfully in medical diagnosis and subclinical neurotoxicity detection. This paper reports VCS measurements in three studies of children in the Czech Republic. Study 1 compared children in standard schools and schools for the learning disabled. Studies 2 and 3 compared children in Teplice, an area in which soft-brown coal combustion produced high levels of pollutants (e.g. Hg, As, SO2, NOx, and aromatic hydrocarbons), with children in areas of low air pollution, Znojmo and/or Prachatice. It was hypothesized that in utero exposure to the combustion products disrupted neurological development (Sram, 1991). The VCS test (Stereo Optical Co.) consisted of circular fields containing sinusoidal gratings at 5 spatial frequencies (1.5-18 cycles/degree) and various levels of contrast. Subjects indicated orientation of the gratings by pointing left, up, or right. Visual acuity and VCS were measured in each eye of 74 children in Study 1,327 second-grade children in Study 2, and 426 fourth-grade children in Study 3. Hair samples were collected in Studies 2 and 3 analyzed for Hg and As content. Children attending schools for the learning disabled scored significantly lower than controls on VCS, whereas visual acuity was normal. The deficit was greatest at mid- to high spatial frequency. In Study 2, significant VCS deficits were seen in exposed second-grade children at low to mid-spatial frequency, even though visual acuity was slightly above control level. Regression analyses showed that VCS had no relationship to As, but a significant negative correlation with hair Hg was observed in the exposed district. However, current Hg levels were higher in Prachatice. VCS deficits were not observed in the fourth-grade students of Teplice in Study 3. The results of Study 1 indicated that behavioral VCS testing in field studies is practical in young, non-English speaking children, and suggested that vision may be compromised in learning-disabled children. Studies 2 and 3 indicated that at these levels, current Hg body-burdens are poor predictors of VCS. If the VCS deficits seen in Study 2 were related to prenatal exposures, the results of Study 3 suggest that they represent a developmental delay. A longitudinal-study design is needed to address this issue.

Child↗

PubMed1983

Spatial contrast sensitivities of X and Y type neurones in the cat's dorsal lateral geniculate nucleus.

The discharges of X and Y type neurones were recorded extracellularly from the binocular segment of the A laminae of the dorsal lateral geniculate nucleus of anaesthetized, paralysed cats. X type geniculate cells are referred to as XG cells and Y type geniculate cells as YG cells. They were differentiated on the basis of a test of linear spatial summation and the relatively higher spatial resolution of the XG type. Contrast sensitivities of these cells were measured for a series of spatial frequencies at 5.2 Hz. Sensitivity measurements took account of the variability inherent in the cells' maintained discharges. Maintained discharges of XG and YG cells were found to be similarly noisy and the level of noise was stable in the time range of seconds to hours. The noise level was greater than in corresponding ganglion cells, suggesting that an extra source of noise is added at the geniculate level. The criterion set routinely to measure 'threshold' contrast corresponded to a level of reliability of about two false positives in fifty. YG cells had higher contrast sensitivities at low spatial frequencies and XG at high. YG cells were found also to have higher peak sensitivities. The optimum spatial frequency of XG cells was found to be higher than that of YG cells. YG cells also show less attenuation in contrast sensitivity for gratings of spatial frequencies below their optima. Contrast sensitivities of both XG and YG cells were found to be lower than those of corresponding ganglion cells. The optimum spatial frequencies and spatial resolutions of XG and YG cells decreased as the retinal eccentricities of their receptive fields increased. XG cells were found to have higher spatial resolution in lamina A than lamina A1. No difference was found between on- and off-centre types of either cell class. Although individual YG cells are more sensitive to low spatial frequencies than individual XG cells, the ensemble of XG cells of one centre-type which overlaps a particular YG cell receptive field of the same centre-type has a contrast sensitivity at optimum spatial frequency very close to that of the YG cell. This leads one to believe that XG cells could by themselves account for the contrast sensitivity of the cat's visual system.

Animals↗

PubMed2000

Contrast sensitivity and visual recovery time in diabetic patients treated with panretinal photocoagulation.

PURPOSE: To study patients treated with panretinal photocoagulation regarding contrast sensitivity and visual recovery time after exposure to glare. METHODS: To compare contrast sensitivity and visual recovery-time after exposure to glare in eyes (n=20) from 20 type 1 diabetic patients treated with panretinal photocoagulation for proliferative retinopathy with eyes (n= 19) from 19 un-treated type 1 diabetic patients. Contrast sensitivity was tested with a low contrast acuity chart, before and during exposure to either a uniform background illumination or a spotlight. Visual recovery time was defined as the time required to regain baseline visual acuity during light exposure. RESULTS: Contrast thresholds values were higher in eyes treated with panretinal photocoagulation compared to un-treated eyes before illumination 4.2 +/- 1.2% vs. 3.1 +/- 1.7% (p=0.006), during background illumination 5.8 +/- 5.1% vs. 3.9 +/- 4.8% (p=0.001), and during spotlight exposure 5.6 +/- 2.2% vs. 3.2 +/- 1.8% (p<0.001). Furthermore, recovery time was longer both during background illumination, 20; 5-50 sec vs. 2; 2-80 sec. (md;range), (p<0.001) and during spotlight illumination 27; 5-70 sec vs. 2;1-60 sec. (md;range) (p<0.001). CONCLUSION: Eyes treated with panretinal photocoagulation had higher contrast threshold levels at baseline and during glare, as well as a prolonged visual recovery time compared to un-treated eyes with mild background retinopathy.

Adolescent↗

PubMed1990

Soft contact lens-induced longitudinal spherical aberration and its effect on contrast sensitivity.

Some investigators have suggested that the poor quality of vision which some spherical, single vision, soft lens-wearing patients report may be a result of spherical aberration induced in the ocular system when a soft lens is placed on the eye. In this study, the longitudinal spherical aberration of spherical soft lenses, both on and off the eye, was calculated using an aspheric corneal model and two-dimensional ray tracing program. Specifically designed front-surface aspheric, soft lenses were produced which demonstrated levels of in-air power variation similar to that calculated for similar-parameter spherically surface lenses. The effect of these lenses on the visual performance of nine subjects was assessed by measuring changes in contrast sensitivity and high contrast visual acuity through 3- and 6-mm artificial pupils. Significant losses of contrast sensitivity were recorded for the spherically aberrated lenses with the 6-mm pupil but not with the 3-mm pupil. High contrast acuity was not affected by any of the aberrated lenses with either the 3- or 6-mm pupils. Theoretical calculations and the contrast sensitivity results indicate that negatively powered lenses produce significantly less spherical aberration in situ than positively powered lenses. Because the majority of the prepresbyopic soft lens-wearing population have low to moderate amounts of myopia, it would appear that soft lens-induced spherical aberration is unlikely to be responsible for the reduction in visual performance which some patients report when corrected with single vision soft lenses.

Contact Lenses, Hydrophilic↗

PubMed1995

Colour contrast sensitivity in patients with soft drusen, an early stage of ARM.

The present institutional study was undertaken in order to determine whether testing of colour contrast sensitivity is valuable in detecting early functional changes in patients at initial stages of age-related maculopathy (ARM). The study included 27 patients with soft drusen as an early sign of ARM and 29 age-matched normals. The area occupied by drusen was determined using a computer program. Colour contrast sensitivity was measured with a computer graphics system. Visual acuity, central visual field (Humphrey Field Analyser) and colour vision (D-15 panel) were normal in both groups. Mean colour contrast sensitivity was significantly lower in patients with early ARM (for the protan axis: p = 0.00019, for the deutan axis: p = 0.000078 and for the tritan axis: p = 0.000096) than in the controls. Interindividual variations were large. There was a tendency towards a bimodal distribution for all three colour axes, most evident for the tritan axis. We found a correlation of the drusen area with the protan and deutan thresholds for the fundus colour photographs r = 0.5 (p < 0.01) and r = 0.4 (p < 0.05), respectively, and with the tritan threshold for the angiograms r = 0.5 (p < 0.05). The findings suggest that colour contrast sensitivity may offer an additional possibility of predicting exudative ARM. Whether the patients with the highest thresholds are those who will be the first to show progression with indications of exudative ARM is not yet known. The patient group will be followed up in order to elucidate this question.

Aged↗

PubMed2003

[Measurement of temporal contrast sensitivity].

OBJECTIVE: The main objective is to present a new prototype designed to test temporal contrast sensitivity, using a flicker stimulus. MATERIAL AND METHOD: We used a radiant surface manufactured with light emitting diode having a dominant wave-length of 626 nm, producing a light spot projected in the central visual field (320). The system uses a flicker stimulus with parameters (light intensity and frequency) that can be varied using a computer. The test group (24 healthy subjects) gave us the possibility to evaluate the test response, to optimise the testing protocol and draw the specific de Lange curve. RESULTS: The test has a very good reproducibility with less then 1% variations between measurements. Distribution of temporal contrast sensitivity follows the de Lange classic curve, the frequencies tested in this experiment being situated on the platou of the curve. We preferred to express the results as minimal light intensity. Within 10 Hz to 30 Hz the results demonstrate little dispersion, with a standard deviation of 0.8% and 2.1% for maximal light intensity of 100% and 50% respectively. CONCLUSIONS: We consider that the prototype can be used for testings of the temporal contrast sensitivity for the central visual field (central 320). The device is simple to use and can well accommodate for outpatient evaluations. We hope that our prototype will be used to monitor minimal changes in the response of the visual system to flicker stimuli.

Adult↗

PubMed2006

Contrast sensitivity and visual hallucinations in patients referred to a low vision rehabilitation clinic.

AIM: To examine the association of reported visual hallucinations and measured visual parameters in adult patients referred for low vision rehabilitation. METHODS: All patients (N = 225) referred to a low vision rehabilitation clinic for a calendar year were asked a standardised question about symptoms of formed visual hallucinations. Best corrected visual acuity and contrast sensitivity using the Pelli-Robson chart were measured. We conducted multiple logistic regression analysis of the association between visual hallucinations and visual parameters. RESULTS: Of the total cohort, 78 (35%) reported visual hallucinations. Visual acuity and contrast sensitivity were considered in four quartiles. In multiple logistic regression controlling for contrast sensitivity, age, gender, report of depression and independence, measured acuity in each of the poorer three categories (compared to the best) was not associated with reported hallucinations. Contrast sensitivity in the three poorer quartiles (compared to the best) was strongly associated with the report of hallucinations (OR 4.1, CI 1.1, 15.9; OR 10.5, CI 2.6, 42.1; OR 28.1, CI 5.6, 140.9) after controlling for acuity, age, sex, depression and independence. CONCLUSIONS: Lowest contrast sensitivity was the strongest predictor of reported hallucinations after adjusting for visual acuity.

Aged↗

PubMed1997

[Contrast vision and contrast sensitivity after binocular implantation of multifocal or monofocal intraocular lenses].

BACKGROUND: Multifocal intraocular lenses show a reduction of contrast due to the simultaneous projection of different images to the retina. In this study we examined if there is also a loss of contrast in bilateral implantation of multifocal lenses. MATERIAL AND METHODS: We examined 22 patients with bilateral AMO ARRAY multifocal intraocular lens and compared these to 20 patients with bilateral monofocal intraocular lens. We performed a monocular and binocular examination of contrast acuify by means of Regan's contrast charts and contrast sensitivity by means of B-VAT-II-SG-Video-acuity-tester. RESULTS: Monocular examination of contrast acuity showed significant superiority of the monofocal intraocular lens at the lowest contrast. Bilateral examination of contrast acuity did not show any significant difference. Monocular contrast sensitivity of the monofocal intraocular lens was significantly superior to the multifocal intraocular lens at two spatial frequencies, but under the bilateral condition there was only a significant difference between the two lenses at the highest spatial frequency. CONCLUSIONS: Bilateral implantation of multifocal intraocular lenses enables contrast acuity and contrast sensitivity that comes very close to the performance of the monofocal intraocular lenses.

Aged↗

PubMed1982

Supraliminal contrast sensitivity functions in recovered optic neuritis.

The supraliminal contrast sensitivity functions in patients with recovered optic neuritis were classified into three function types: 1) type with a decrease in sensitivity in the high and an increase in the low spatial frequency region, 2) type with flat shape as found in normal subjects, and 3) type with a decrease in the low and an increase in the high frequency region. These abnormal functions may be explained by an inhibitory interaction between two parallel channels of high and low frequency, which may have a dependence on the most central and the paracentral region in the visual fields, respectively. The measurements of the supraliminal contrast sensitivity functions are clinically useful for understanding the visual processes in cases with recovered optic neuritis.

Adult↗

PubMed1993

Individual differences in contrast sensitivity functions: the first four months of life in humans.

Contrast sensitivity functions of forty 4-month-old human infants were measured using a preferential-looking method and the method of constant stimuli. Circular sinewave gratings varied from 0.27 to 1.08 c/deg, contained eight unattenuated cycles (with edges tapered to uniform gray), and rose to the desired contrast in 2 sec. Log contrast sensitivities for variables close in spatial frequency correlated more highly than those that were farther apart in these data, and in data of 1-, 2-, and 3-month-olds from Banks and Salapatek [(1981) Journal of Experimental Child Psychology, 31, 1-45]. Factor analyses yielded at least two frequency-tuned factors per age group. Monte Carlo simulations of a quantitative model that shifts spatial mechanisms to higher frequencies with age reproduced the results for 4-month-olds, but simulations of adultlike, unshifting mechanisms did not. The data are consistent with the following conclusions: (a) individual differences in the sensitivity of spatial mechanisms may explain some individual differences in CSFs; (b) factor analysis may help to estimate mechanism tuning; and (c) spatial mechanisms may shift to higher frequencies during development.

Contrast Sensitivity↗

PubMed2005

Improving the design of the letter contrast sensitivity test.

PURPOSE: To develop a small-format letter contrast sensitivity test with improved accuracy, suitable for portable use and near testing, and having a simple and unambiguous scoring system that can be used with reference to existing norms. METHODS: A near test, printed on resin-coated paper and mounted on plastic was developed by using Sloan letters, with 0.04 log unit contrast decrements between each letter and a simple scoring procedure. Monte Carlo methods and a Weibull function model of visual performance were used to assess test accuracy. RESULTS: The new test has 28% lower score standard deviations than the Pelli-Robson Contrast Sensitivity Chart, over a wide range of low misreporting rates, while maintaining test scores that differ from the Pelli-Robson by 0.01 log unit, permitting use of norms collected with the Pelli-Robson test. CONCLUSIONS: While maintaining comparability with Pelli-Robson norms, the new test has improved accuracy in comparison with the Pelli-Robson chart and several other advantages that result from its smaller size.

Contrast Sensitivity↗

PubMed2005

Visual acuity and contrast sensitivity comparison between Tecnis and AcrySof SA60AT intraocular lenses: A multicenter randomized study.

PURPOSE: To evaluate best corrected visual acuity (BCVA) and photopic and mesopic contrast sensitivity in pseudophakic patients implanted either with the aspheric intraocular lens (IOL) designed to correct for corneal spherical aberration or with a conventional IOL. SETTING: Three surgical centers participated this prospective randomized masked comparative study. METHODS: Thirty eyes of 30 patients after aspheric lens implantation (Pfizer/Pharmacia Tecnis Z9000) were compared with 30 eyes of 30 age-matched patients after conventional lens implantation (Alcon AcrySof SA60AT). Two to three months after surgery, best spectacle corrected distance visual acuity was measured using the Early Treatment Diabetic Retinopathy Study chart. Contrast sensitivity was measured by sinusoidal grating charts for distance at photopic (85 cd/m(2)) and mesopic (6 cd/m(2)) luminance level with optical correction in place. Tested spatial frequencies were 1.5, 3, 6, 12, and 18 cycles per degree (cpd). RESULTS: The mean BCVA was -0.053 +/- 0.044 logMAR in eyes with the aspheric Tecnis IOL and 0.006 +/- 0.059 logMAR in eyes with the conventional AcrySof IOL (P=.0001). Eyes with the aspheric IOL showed better contrast sensitivity at spatial frequencies of 3 cpd (P<.05) and 6, 12, and 18 cpd (P<.01) in photopic and in mesopic conditions. Peak improvement occurred at 18 cpd and was 36% (0.29 log units) in photopic and 54% (0.27 log units) in mesopic conditions. CONCLUSIONS: The aspheric Tecnis IOL yielded better BCVA and better distance contrast sensitivity than the conventional IOL. The differences were clinically significant for higher spatial frequencies. The results give some suggestions for further studies.

Aged↗

PubMed2006

[The comparison of visual acuity and contrast sensitivity in patients with cataract and age-related macular degeneration implanted with foldable or rigid intraocular lenses].

OBJECTIVE: To evaluate the maximally corrected visual acuity and contrast sensitivity under photopic and mesopic conditions with or without glare in pseudophakic patients implanted with either foldable or rigid intraocular lenses. MATERIAL AND METHODS: A total of 83 patients after cataract surgery were examined at baseline and 8-12 weeks later: 47 patients with age-related macular degeneration (Group 1) and 36 patients without ocular comorbidities (Group 2). Contrast sensitivity was measured using a Ginsburg Box, VSCR-CST-6500. RESULTS: Using logistic regression analysis it was revealed that probability of clinically significant improvement of contrast sensitivity under photopic conditions with and without glare in the patients with implanted foldable lenses increased by 3.1 times (95% PI 1.6-5.9, P<0.001) compared with the patients with rigid lenses. In mesopic conditions with and without glare, it increased by 3.9 and 3.0 times (95% PI 1.9-7.8 and 1.6-5.9, respectively, P<0.001) in the patients with foldable lenses as compared with the patients with rigid lenses. CONCLUSIONS: The foldable intraocular lenses have shown better contrast sensitivity than rigid lenses under both mesopic and photopic conditions with or without glare. Postoperatively, there was no significant difference in visual acuity concerning the types of the implanted intraocular lenses.

Contrast Sensitivity↗

PubMed1990

Infant spatiotemporal vision: dependence of spatial contrast sensitivity on temporal frequency.

Effects of temporal frequency on infant spatial contrast sensitivity were studied with forced-choice preferential looking, using localized 1.0 and 0.35 c/deg grating patches. Between 4 and 8 months, contrast sensitivity at 1.0 c/deg increased significantly at 8-17 Hz but showed little change at 2-4 Hz, so temporal tuning became increasingly bandpass with age. At 4 months, temporal tuning was lowpass at 1.0 c/deg and bandpass at 0.35 c/deg. Control data on adults indicate that the differences between the infant and adult data cannot be accounted for solely by reduced photoreceptor density and quantal catch, and suggest developmental changes in tuning and/or relative sensitivities of spatiotemporal mechanisms.

Adult↗

PubMed1994

Impaired contrast sensitivity in adolescents and young type 1 (insulin-dependent) diabetic patients with microalbuminuria.

We compared neurosensorial visual function by psychophysical tests (macular recovery time and contrast sensitivity) in two well matched groups of young Type 1 (insulin-dependent) diabetic patients with micro- and normoalbuminuria, respectively. The patients had normal visual acuity (> or = 1.0) and either no retinopathy or non-proliferative retinopathy. Thirty patients with microalbuminuria (albumin excretion > or = 15 micrograms/min in a least two out of three timed overnight urine samples) were matched (age, diabetes duration, mean one-year HbA1c, gender) with normoalbuminuric (n = 27) patients. Retinopathy (50 degree colour fundus photography) was assessed by counting microaneurysms and hemorrhages as 'red spots'. Contrast sensitivity was examined for the spatial frequencies of 1.5, 3, 6, 12 and 18 cycles per degree (cpd). Macular recovery time (nyctometry) refers to the time-related (2 min) ability of the retina to regain visual acuity following exposure to bright light (photostress). Contrast sensitivity score was reduced in patients with microalbuminuria compared to those without; 18 cpd (mean and 95% confidence intervals): [4.2 (3.8-4.7) vs 5.0 (4.6-5.4), p = 0.03]. Macular recovery performance was not significantly reduced: [21.0 arbitrary units (17.5-24.6) vs 26.0 (22.6-30.7), p = 0.12]. We conclude that impaired contrast sensitivity independent of background retinopathy is shown in a group of young Type 1 (insulin-dependent) diabetic patients with low-grade microalbuminuria compared to a group of patients with normoalbuminuria.

Adolescent↗