Search PubMed⌕ Search

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.

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

At least 397 records · Page 22Linked to original sources
PubMed1986

Macular electroretinograms and contrast sensitivity as sensitive detectors of early maculopathy.

Eighteen patients with early maculopathies of various etiologies were tested with pattern and focal electroretinograms (macular ERGs), with high (400 cd/M2) and moderate (40 cd/M2) stimulus intensities and a four-alternative forced choice (4AFC) contrast sensitivity test in addition to intensive clinical examinations. High spatial frequency contrast sensitivity loss on the 4AFC test was the most striking and consistent feature of all cases. The only eyes not outside normal contrast sensitivity limits were three in which diagnosis was uncertain and the patients had not recognized any problem, including two marginal solar burns. Maculopathy also substantially reduced macular ERG amplitudes. Criterion scores on these tests separated patients from normals more effectively than other noninvasive procedures and only missed one eye detected by contrast sensitivity. Latencies were affected but the delays were of no clinical significance in the individual case. Stimulus intensity was not critical. The results indicate that contrast sensitivity testing and macular ERGs are very reliable indices of central visual dysfunction at a stage when visible macular changes are too subtle for confident diagnosis. Contrast sensitivity has appeal because of its reliability, objectivity, simplicity, and noninvasive nature. It is equally applicable to children and adults. Pattern and focal ERGs can establish that the visual deficit has a retinal origin and can provide the most reliable objective confirmation.

Electroretinography↗
PubMed1987

Do Y geniculate neurons have greater contrast sensitivity than X geniculate neurons at all visual field locations?

Contrast sensitivities for gratings of different spatial frequencies drifting at 5.2 Hz were measured for X- and Y-type neurons of the cat's dorsal lateral geniculate nucleus. It was found that, for cells with neighboring receptive fields, the peak contrast sensitivities of Y-type cells were always greater than those of X-type cells. This greater contrast sensitivity of Y geniculate cells was found not to depend on the area of visual field in which the cells' receptive fields were located.

Animals↗
PubMed1989

Glare and contrast sensitivity in contact lens corrected aphakia, epikeratophakia and pseudophakia.

The effects of glare on contrast sensitivity and high contrast Snellen acuity were investigated in a group of unilaterally aphakic patients with normal fellow eyes. In spite of relatively good visual acuity and apparently satisfactory surgical results, there was a marked reduction in contrast sensitivity in epikeratophakia and contact lens corrected aphakic eyes, relative to fellow normal eyes, especially in the presence of glare (P less than 0.05). Although the results from the pseudophakic patients were more variable, there is some evidence to suggest that epikeratophakia provides inferior visual function to contact lens correction or intraocular lens implantation. The results also suggest that the measurement of visual acuity in the presence of glare fails to identify many patients with a functional visual impairment secondary to glare.

Adolescent↗
PubMedDate not supplied

Effect of a yellow filter on contrast sensitivity and disability glare after laser in situ keratomileusis under mesopic and photopic conditions.

PURPOSE: To analyze the effect of a yellow filter on contrast sensitivity and disability glare under mesopic and photopic luminance conditions in laser in situ keratomileusis (LASIK) patients and control subjects. METHODS: Contrast sensitivity with and without glare was determined in 27 patients who had undergone LASIK at least 1 year previously and in 30 control subjects. Tests were performed with and without a coated yellow filter (X-482 nm cut-off) using the Mesotest II or Mesoptometer II (Oculus, Wetzlar, Germany) under mesopic conditions, and the Contrast Glaretester 1000 (Takagi, Seiko Co Ltd, Nagano, Japan) under photopic conditions. RESULTS: Under mesopic conditions, log contrast sensitivity without glare decreased by 0.14 log units in the LASIK group. When the yellow filter was used, this variable showed a significant increase of 0.04 log units and the proportion of patients able to discriminate the mesopic contrast limit of 1:5 rose from 70% to 78%. With glare, the yellow filter also improved contrast sensitivity in LASIK patients, but not significantly. Under photopic conditions, no statistical differences were observed between results obtained with and without the yellow filter in the LASIK group or between the LASIK and control group without glare. CONCLUSIONS: Mesopic contrast sensitivity without glare was worse in LASIK patients and increased significantly with the yellow filter. The filter had no effect under photopic conditions. No disability glare differences were noted between the LASIK and control groups or between the LASIK without and with filter groups under mesopic and photopic conditions.

Adult↗
PubMed2005

Contrast sensitivity as an outcome measure in patients with subfoveal choroidal neovascularisation due to age-related macular degeneration.

PURPOSE: Although visual acuity is the most frequently used primary outcome measure in clinical trials of treatments for choroidal neovascularisation (CNV) due to age-related macular degeneration (AMD), contrast sensitivity may provide valuable additional information. This paper reviews the evidence for using contrast sensitivity as a measure of visual function and as an outcome measure in clinical trials in patients with subfoveal CNV due to AMD. METHODS: Medline database searches were performed to retrieve relevant articles on contrast sensitivity. In addition, articles were included from the authors' knowledge of the literature and from the reference lists of retrieved articles. RESULTS: The published literature demonstrates that contrast sensitivity is an important measure of visual function in patients with subfoveal CNV due to AMD. Most clinical trials of treatments for CNV due to AMD have reported visual acuity as the primary outcome. However, there is evidence that treatment (such as verteporfin therapy) may also provide additional benefits in terms of contrast sensitivity. These benefits may not be completely characterised by measurement of visual acuity alone. CONCLUSIONS: The inclusion of contrast sensitivity as an outcome measure in studies of patients with CNV due to AMD may provide a more complete understanding of the effects of treatment on visual function and the likely benefits for patients.

Activities of Daily Living↗
PubMed2006

Covert attention increases contrast sensitivity: Psychophysical, neurophysiological and neuroimaging studies.

This chapter focuses on the effect of covert spatial attention on contrast sensitivity, a basic visual dimension where the best mechanistic understanding of attention has been achieved. I discuss how models of contrast sensitivity, as well as the confluence of psychophysical, single-unit recording, and neuroimaging studies, suggest that attention increases contrast sensitivity via contrast gain, an effect akin to a change in the physical contrast stimulus. I suggest possible research directions and ways to strengthen the interaction among different levels of analysis to further our understanding of visual attention.

Action Potentials↗
PubMedDate not supplied

[Spatial contrast sensitivity in the differential diagnosis of optic neuritis].

Contrast sensitivity was examined in patients with optic neurites of different etiology. Achromatic and chromatic (red-black, green-black, and blue-black) sinusoidal patterns were presented in succession against the black background at a frequency of 1-22 cycles/degree on the monitor of an IBM computer. Contrast sensitivity was found altered during exacerbation of optic neuritis on both involved and intact eyes, this indicating a possible involvement of the chiasmal region. The authors discuss a new approach to investigation of the mechanisms of impairment of the optic nerve in optic neuritis in the presence of disseminated sclerosis and neuritis of obscure etiology.

Adolescent↗
PubMed1996

Contrast sensitivity after wearing prisms to correct for heterophoria.

Contrast sensitivity to sinusoidal gratings was measured at spatial frequencies of 1.5-16 c/deg in 8 subjects before and after wearing prisms (for at least two weeks) to correct heterophoria, prescribed by the full correction method of H.J. Haase (Binocular testing and distance correction with the Berlin Polatest [trans. W. Baldwin]. J. Am. Optom. Assoc. 34, 115-125, 1962). At higher spatial frequencies of 12-16 c/deg, we found an average improvement in contrast sensitivity of 0.15 log unit. This effect is estimated to correspond to an increase in visual acuity of 15%.

Adult↗
PubMed2001

Hypercapnia invokes an acute loss of contrast sensitivity in untreated glaucoma patients.

BACKGROUND/AIM: It is widely accepted that hypercapnia results in increased retinal, choroidal, and retrobulbar blood flow. Reports of a visual response to hypercapnia appear mixed, with normal subjects exhibiting reduced temporal contrast sensitivity in some studies, while glaucoma patients demonstrate mid-peripheral visual field improvements in others. This suggests that under hypercapnic conditions a balance exists between the beneficial effects of improved ocular blood flow and some other factor such as induced metabolic stress; the outcome may be influenced by the disease process. The aim of this study was to evaluate the contrast sensitivity response of untreated glaucoma patients and normal subjects during mild hypercapnia. METHODS: 10 previously untreated glaucoma patients and 10 control subjects were evaluated for contrast sensitivity and intraocular pressure while breathing room air and then again during mild hypercapnia. RESULTS: During room air breathing, compared with normal subjects, glaucoma patients had higher IOP (p = 0.0003) and lower contrast sensitivity at 3 cycles/degree (cpd) (p = 0.001). Mild hypercapnia caused a significant fall in contrast sensitivity at 6, 12, and 18 cpd (p < 0.05), only in the glaucoma group. CONCLUSION: Glaucoma patients with early disease exhibit central vision deficits as shown by contrast sensitivity testing at 3 cpd. Hypercapnia induces further contrast loss through a range of spatial frequencies (6-18 cpd) which may be predictive of further neuronal damage due to glaucoma.

Case-Control Studies↗
PubMed1998

Contrast sensitivity after implantation of diffractive bifocal and monofocal intraocular lenses.

PURPOSE: To compare contrast sensitivity (CS) after implantation of a diffractive bifocal intraocular lens (IOL) and a monofocal IOL of similar design. SETTING: Seven European centers. METHODS: In this randomized, prospective study, CS was tested 5 months after cataract and IOL implantation surgery in 115 patients with a diffractive bifocal IOL and 106 patients with a monofocal IOL. It was also tested in a subgroup of 38 patients who had bilateral implantation of a diffractive bifocal IOL. Contrast sensitivity was tested using the Vision Contrast Test System (VCTS). RESULTS: In patients with a best corrected visual acuity (BCVA) of 1.0 or better, the CS at all spatial frequencies (1.5 to 18 cycles/degree), both at distance and near, was slightly lower in the bifocal IOL group than in the monofocal group. Mean values were within the normal range. In patients with a BCVA of less than 1.0, the CS was lower and the difference between the bifocal and monofocal groups was less. In patients with bilateral bifocal IOLs, CS was better when tested bilaterally than when testing the better eye alone. Pupil size affected the results to a small degree. Contrast sensitivity appeared to improve over time after implantation of a diffractive bifocal IOL. CONCLUSIONS: In patients with cataract and no other eye pathology, the diffractive bifocal IOL with slightly reduce the CS at all spatial frequencies. In those with reduced visual acuity after cataract surgery, CS will be reduced accordingly. In this situation, the reduction from the diffractive bifocal optic would be minor.

Aged↗
PubMed1982

Contrast sensitivity predicts pilots' performance in aircraft simulators.

Contrast sensitivity was found to be better than visual acuity for predicting a pilot's ability to detect a small, semi-isolated, air-to-ground target. Eleven instructor pilots had their acuity measured by both conventional and contrast sensitivity methods. Scotopic contract sensitivity showed the highest correlation with slant detection range (0.83). Conventionally determined visual acuity proved to be a poor predictor of a pilot's ability to detect a small low contrast target.

Adult↗
PubMed2002

Structural modeling of contrast sensitivity in adulthood.

Structural equation modeling was used to assess the utility of the sensorineural model of contrast sensitivity proposed by Sekuler et al. [Vision Res. 24, 689 (1984)] to account for spatial vision in adulthood. In Study 1, visual acuity and contrast sensitivity (1.5-18 c/deg) were measured in 84 people between the ages of 19 and 81 yr. No three-filter model fitted the data well. Although a two-filter model was associated with good fit indices, parameter estimates for both filters were inconsistent with physiological and behavioral data. In Study 2, acuity and contrast sensitivity (1.5-18 c/deg) were assessed in 95 observers between the ages of 23 and 73 yr. All measures were gathered once per month over a three-month period. The Sekuler et al. three-filter model did not fit the data from any time of measure, but a two-filter, bandpass model provided a consistent and excellent fit for all three waves. The model suggests that age-related change in the neural mechanisms underlying contrast sensitivity is minimal once acuity is controlled. Discrepancies between this conclusion and that reported by Sekuler et al. may be related to test type, psychophysical method, reliability, and sample selection.

Adult↗
PubMedDate not supplied

The objective assessment of visual contrast sensitivity by pattern reversal visual evoked potentials in diabetes.

Recent studies have described abnormalities of visual evoked potentials and pattern electroretinography in diabetics without retinopathy. The visual contrast sensitivity, determined by psychophysical tests, has proved to be abnormal in diabetic patients with and without clinical retinopathy. In this study we evaluated contrast sensitivity function using both electrophysiologic and psychophysical methods. The objective assessment of functional visual contrast sensitivity was superior to psychophysical evaluation in the detection of contrast sensitivity alterations. No relationships were found between contrast sensitivity dysfunction and abnormalities of pattern electroretinography or fluorescein angiography. Our data suggest that functional visual deficits might precede background retinopathy and that the involvement of foveal function is early and very frequent in diabetic patients, even if they have normal visual acuity.

Adolescent↗
PubMed2001

Contrast sensitivity function in patients with impaired oral glucose tolerance.

PURPOSE: To evaluate contrast sensitivity function in patients with impaired oral glucose tolerance test (OGTT) compared with normal subjects. METHODS: Sixteen patients with impaired OGTT and 11 normal control subjects were tested for contrast sensitivity function at four spatial frequencies. Glucose intolerance was established by the 1985 World Health Organization criteria. RESULTS: The two groups were similar in terms of age, visual acuity, refractive correction, and lens opacities. A statistically significant loss of contrast sensitivity was associated with impaired OGTT (p < 0.001) in every spatial frequency tested. CONCLUSIONS: Functional visual loss in patients with impaired glucose tolerance using the 1985 World Health Organization criteria indicates that at least part of those patients should be classified as diabetic according to the 1997 American Diabetic Association criteria. It seems that the 1997 American Diabetic Association criteria are more efficient at detecting patients with abnormal visual function.

Adult↗
PubMed1987

Contrast sensitivity and pattern visual evoked potential in patients with glaucoma.

Contrast sensitivity and pattern visual evoked potential (VEP) were measured in cases of ocular hypertension and primary open-angle glaucoma at various stages. The visual field of each eye was examined quantitatively and the retinal nerve fiber layer and optic disc were precisely assessed with magnified stereoscope fundus photography. This study revealed that contrast sensitivity of the eyes with glaucoma was within the normal range in the very early stage of the disease. As optic nerve damage advanced, high- or low-frequency loss developed. Further optic nerve damage produced a level type of loss. Pattern VEPs also showed increasing abnormalities as glaucomatous optic nerve damage progressed. Measurements of contrast sensitivity and pattern VEP were found not to be as sensitive as quantified precise visual field measurement or color stereoscopic fundus photography for detection of minor optic nerve damage in cases of early glaucoma. These methods may be useful, however, as an objective and subjective monitor of progression of optic nerve damage in glaucoma.

Adolescent↗
PubMed1997

[Contrast sensitivity of several blindness-inducing eye diseases and the influence of tinted filter lens].

OBJECTIVES: To evaluate the effects of tinted filter lens on the visual rehabilitation of blind and low vision patients induced by optic nerve atrophy, glaucoma and retinitis pigmentosa. METHODS: The contrast sensitivity of 22 cases with optic nerve atrophy (34 eyes), 17 glaucoma (30 eyes), 18 retinitis pigmentosa (30 eyes) and 30 normal people (60 eyes) with and without yellow and red filter lens was tested. RESULTS: The results demonstrated that a yellow filter lens could improve the optic nerve atrophy patient's contrast sensitivity at 1.5, 3, 6 and 12 c/deg, while a red filter lens could increase the contrast sensitivity at limited spatial frequencies, but it could also decrease the contrast sensitivity at some other spatial frequencies. CONCLUSION: Yellow filter lens could be applied as a non-optical visual aid in the visual rehabilitation of the blind and low vision patients induced by these three diseases, as the above results show contrast sensitivity improvement in the low spatial frequency and the peak of the contrast sensitivity curves.

Adolescent↗
PubMed1994

[Do radiologists develop perceptual learning contrast sensitivity?].

A slight difference in brightness between objects close to each other and with no clear-cut outlines separating them can be recognized by the visual function called contrast sensitivity. This function is particularly developed in the radiologist, whose task is to analyze images in many shades of grey and with no clear-cut outlines, due to kinetic and radiogeometrical shading. Assuming that professional habit might develop this function, the authors compared contrast sensitivity in a group of 26 radiologists with contrast sensitivity in a control group (30 non-radiologists). The Vistech VTCS 6500 test was chosen for the task because of its practicality and reliability. The test consists in the recognition of the orientation of 5 series of alternate bright and dark lines differencing in thickness and contrast. The results obtained in the two groups were studied and compared with the statistical test of the analysis of variance, the T-test by Student and the U-test by Mann-Whitney. Contrast sensitivity was surprisingly higher in the radiologists group, in 4 of 5 series of images with bright and dark lines, than in controls and the difference was statistically significant: p < 0.001 with the test and the U-test. A deviation standard increase in contrast sensitivity was found also in radiologists with short-term professional activity (a few years). To explain these results, two hypotheses one suggested by the authors: radiologists pay greater attention to image details, because of their profession; perceptual learning--that is an improvement in the image-research cortical function--might occur, because of constant training. In the radiologist to conclude repeated stimulation of research capabilities in low-contrast images is thought to improve the efficiency of this cortical function.

Adult↗
PubMed2006

Comparison of higher order aberrations and contrast sensitivity after LASIK, Verisyse phakic IOL, and Array multifocal IOL.

PURPOSE: To evaluate higher order aberrations and contrast sensitivity after LASIK, implantation of the Verisyse phakic intraocular lens (IOL), and refractive lens exchange with the Array multifocal IOL. METHODS: In a prospective, non-randomized case series, LASIK was performed in 20 eyes with the Technolas 217z excimer laser (Bausch & Lomb, Rochester, NY), a Verisyse phakic IOL (AMO Inc, Santa Ana, Calif) was implanted in 11 eyes, and refractive lens exchange with implantation of a multifocal IOL (Array IOL, AMO Inc) was performed in 12 eyes. Wavefront error (Zywave aberrometer; Bausch & Lomb) at two pupil sizes (4 and 6 mm) and photopic contrast sensitivity (CVS-1000) was measured preoperatively and 2 months postoperatively in all eyes. RESULTS: Photopic contrast sensitivity remained unchanged in the LASIK and the Verisyse groups, and decrease was significant in the Array group at three cycles per degree only. Higher order aberrations with a 4-mm pupil were increased in the Array group only. With a 6-mm pupil, they were increased in all groups. Comparing groups, surgically induced higher order aberrations were highest after refractive lens exchange with the Array multifocal IOL and lowest after implantation of the Verisyse IOL. CONCLUSIONS: Laser in situ keratomileusis, the Verisyse IOL, and the Array IOL increase higher order aberrations at large pupil sizes, but no increase occurs at small pupil sizes with LASIK or the Verisyse IOL. Contrast sensitivity in photopic conditions is normal with LASIK and the Verisyse IOL, but slightly reduced with the Array IOL due to the multifocal optic.

Adult↗