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PubMed1988

Changes in contrast sensitivity induced by spherical hydrogel lenses on low astigmats.

Contrast sensitivity values were taken on seven astigmatic (cylinder correction under 1.00 diopter) and eight spherical myopes using the Vistech VCTS 6500 System. For the astigmatic group, no significant difference in contrast sensitivity was found between the full subjective correction and an equivalent spherical spectacle prescription, despite the absence of cylinder correction. However, comparing the full subjective correction with an equivalent spherical hydrogel lens, we found a significant decrease in contrast sensitivity while wearing lenses for all but the highest spatial frequency tested. Using a group of spherical myopes, we were unable to demonstrate a decrease in contrast sensitivity as a product of hydrogel lens wear alone. Our findings suggest that there is a measurable decrease in contrast sensitivity as a result of fitting low astigmats with spherical hydrogel lenses which cannot be attributed solely to hydrogel lens wear or the absence of cylinder correction.

Adult↗
PubMed1998

Visual acuity versus letter contrast sensitivity in early cataract.

Large and small letter contrast sensitivity and visual acuity were assessed in 37 elderly eyes (mean VA -0.01 logMAR, Snellen 6/6) and their lens opacities were categorised and graded using the LOCS III system. Large letter contrast sensitivity was often not reduced in cataract from age-matched normal values and provided limited information. Small letter contrast sensitivity was shown to be a more sensitive measure of early cataract than visual acuity and large letter contrast sensitivity. Its usefulness may be limited by its strong correlation with visual acuity (r2 = 0.70), which is the standard and traditional measure of vision in cataract.

Aged↗
PubMed2004

Effect of positive and negative defocus on contrast sensitivity in myopes and non-myopes.

This study investigated the effect of lens induced defocus on the contrast sensitivity function in myopes and non-myopes. Contrast sensitivity for up to 20 spatial frequencies ranging from 1 to 20 c/deg was measured with vertical sine wave gratings under cycloplegia at different levels of positive and negative defocus in myopes and non-myopes. In non-myopes the reduction in contrast sensitivity increased in a systematic fashion as the amount of defocus increased. This reduction was similar for positive and negative lenses of the same power (p = 0.474). Myopes showed a contrast sensitivity loss that was significantly greater with positive defocus compared to negative defocus (p = 0.001). The magnitude of the contrast sensitivity loss was also dependent on the spatial frequency tested for both positive and negative defocus. There was significantly greater contrast sensitivity loss in non-myopes than in myopes at low-medium spatial frequencies (1-8 c/deg) with negative defocus. Latent accommodation was ruled out as a contributor to this difference in myopes and non-myopes. In another experiment, ocular aberrations were measured under cycloplegia using a Shack-Hartmann aberrometer. Modulation transfer functions were calculated using the second order term for defocus as well as the fourth order Zernike term for spherical aberration. The theoretical maximal contrast sensitivity based on aberration data predicted the measured asymmetry in contrast sensitivity to positive and negative defocus that was observed in myopic subjects. The observed asymmetry in contrast sensitivity with positive and negative defocus in myopes may be linked to the altered accommodative response observed in this group.

Accommodation, Ocular↗
PubMed2003

Comparison of contrast sensitivity, visual acuity, and Humphrey visual field testing in patients with glaucoma.

BACKGROUND: Despite their normal or near-normal Snellen visual acuity, patients with glaucoma often complain of "poor" vision. OBJECTIVE: To investigate the relationship between large-letter contrast sensitivity, high-contrast visual acuity, and visual field defects in patients with glaucoma who have 20/40 or better visual acuity. DESIGN: Prospective, cross-sectional case series. PATIENTS AND METHODS: We evaluated 250 eyes of 144 subjects from the Glaucoma Service at the University of Illinois at Chicago College of Medicine. Subjects with a diagnosis of glaucoma, suspected glaucoma, or ocular hypertension who met the 20/40 or better vision requirement were recruited. Visual acuity was measured using the rear-illuminated Lighthouse Visual Acuity Chart at 4 m. Contrast sensitivity was measured using the Pelli-Robson Chart in a front-illuminated box with even luminance across the chart. Visual fields of the patients were measured using the 24-2 full-threshold program on the Humphrey Visual Field Analyzer. RESULTS: A significant correlation (r = 0.57, P < 0.001, n = 127) was found between the visual field mean deviations and the contrast sensitivity scores. The correlation (r = -0.322, P < 0.001, n = 127) was less between the visual field mean deviation and the log MAR visual acuity values, as was the correlation between the contrast sensitivity scores and log MAR visual acuity values (r = -0.370, P < 0.001, n = 127). In the subgroup of patients with chronic open-angle glaucoma, the correlation between the mean visual field deviation and the contrast sensitivity score was higher at 0.689 (P < or = 0.001, n = 62). CONCLUSIONS: Reduced contrast sensitivity is significantly correlated with visual field losses in patients with glaucoma and a visual acuity of 20/40 or better. The study data support the conclusion that, compared with visual acuity, the disease process preferentially affects contrast sensitivity. In our previous work, contrast sensitivity was shown to be more related than visual acuity to real-world function in patients with early glaucomatous changes.

Contrast Sensitivity↗
PubMed1979

[Neuro-ophthalmological problems: the diagnostic value of contrast sensitivity].

The evaluation of the individual contrast sensitivity function may prove useful in cases affected by lesions of the optic pathways, even when the usual neuro-ophthalmological tests (i.e. visual acuity, visual field examination) are normal. The contrast sensitivity function represents an alternative method to assess the power of spatial resolution of the visual system: in particular, it enables to measure the sensitivity at high, medium and low ranges of spatial frequencies, this being unique to such a procedure. The possible physiological mechanisms underlying the contrast sensitivity function as well as its pathological changes are reviewed.

Form Perception↗
PubMed2002

Contrast sensitivity in a dynamic environment: effects of target conditions and visual impairment.

Contrast sensitivity was determined as a function of target velocity (0 degrees - 120 degrees/s) over a variety of viewing conditions. In Experiment 1, measurements of dynamic contrast sensitivity were determined for 24 male and 24 female observers as a function of target velocity for letter stimuli of 2 sizes and 2 durations. Significant main effects were found for target velocity, target size, and target duration, but significant interactions among the variables indicated especially pronounced adverse effects of increasing target velocity for small targets and brief durations. In Experiment 2, the effects of simulated cataracts on dynamic contrast sensitivity were determined for 10 male and 10 female observers. Although the simulated impairment had no effect on traditional acuity scores, dynamic contrast sensitivity was markedly reduced under all conditions but especially with the smaller targets and at higher velocities. Results are discussed in terms of dynamic contrast sensitivity as a useful composite measure of visual functioning that may provide a better overall picture of an individual's visual functioning than does traditional static acuity, dynamic acuity, or contrast sensitivity alone. The measure of dynamic contrast sensitivity may increase understanding of the practical effects of various conditions, such as aging or disease, on the visual system, or it may allow improved prediction of individuals' performance in visually dynamic, situations, such as driving and sports.

Adolescent↗
PubMed2003

[Static and dynamic contrast sensitivity of myopic eyes before and after laser in situ keratomileusis].

OBJECTIVE: To evaluate the static and dynamic contrast sensitivity changes in myopic patients before and after laser in situ keratomileusis (LASIK). METHODS: Seventy-three eyes in 37 patients with myopia (with or without astigmatism) who received LASIK were tested for static and dynamic contrast sensitivities using the METRO VISION MON ELEC I system at 0.7, 1.4, 2.7, 5.5, 11, and 22 cpd and cps prior to LASIK, and at one-, three-, and six-month intervals after LASIK. RESULTS: All eyes gained naked visual acuity of more than 0.5 after LASIK. The contrast sensitivity was depressed at all frequencies 1 month after LASIK, as compared to one week prior to LASIK. The depression at 2.7, 5.5, 11 (P < 0.01) and 22 cpd (P < 0.05) was statistically significant for static contrast sensitivity, and also at 5.5 (P < 0.01) and 11 cps (P < 0.05) for dynamic contrast sensitivity. Myopic eyes between 6.25 D and 14.0 D, and astigmatic eyes 2 DC and more, suffered more static and dynamic contrast sensitivity depression than the myopic eyes between 1.25 D and 6.00 D and astigmatic eyes less than 2 DC. Contrast sensitivities were improved and exceeded preoperative levels 3 months after LASIK, and improved even more 6 months after LASIK. All sequences were statistically significant for static contrast sensitivity (P < 0.01), while only 2.7, 5.5, and 11 cps were statistically significant for dynamic contrast sensitivity (P < 0.01). The astigmatic eyes 2 DC and more showed less improvement, even below the preoperative level at 1.4 cps of dynamic contrast sensitivity. CONCLUSIONS: While temporary depression of contrast sensitivity for myopic eyes after LASIK was seen, contrast sensitivity soon returned to exceed preoperative levels at 3 months after LASIK, while improving even more 6 months after LASIK.

Adolescent↗
PubMed1984

A new contrast sensitivity vision test chart.

A new contrast sensitivity vision chart has been tested and compared to an automated video-based vision tester on 83 observers whose ages ranged from 9 to 75 years. Good agreement was found between the contrast sensitivity measurements obtained from the vision chart and the automated tester for similar population and age variations. These results suggest that vision test charts can be developed to provide useful contrast sensitivity psychometric functions and yet be as simple to use as present eye charts.

Adolescent↗
PubMed1988

Analysis of the development of spatial contrast sensitivity in monkey and human infants.

The development of spatial contrast sensitivity in human and monkey infants reveals changes in the properties of underlying contrast-detection mechanisms in the visual system. A reanalysis of published data shows that the development of the spatial contrast sensitivity function can be described satisfactorily by the simultaneous vertical and horizontal scaling of a template function whose shape on a log-log axis does not change during development. Because individuals differ in the point to which contrast sensitivity has developed at any particular time, the use of group-averaged data as a basis for estimating the course of the developmental process has two undesirable results. First, it provides estimates of spatial contrast sensitivity during development that do not reflect any individual's sensitivity. Second, it incorrectly suggests that the shape of the spatial contrast sensitivity function changes during development.

Aging↗
PubMed1995

Effects of flurbiprofen and indomethacin on acute cystoid macular edema after cataract surgery: functional vision and contrast sensitivity.

We examined the effect of acute cystoid macular edema (CME) on contrast sensitivity. Eyedrops were instilled into the surgically treated eye f1p4 times daily for two days preoperatively and for three months postoperatively. Angiographic and clinical CME were measured, as were contrast sensitivity and Snellen acuity. Jaeger visual acuity equivalents were calculated and digital imaging techniques used to simulate visual function. We found that angiographic CME reduces functional vision as measured by contrast sensitivity and visual acuity over a large range of sizes. In patients treated with the flurbiprofen vehicle, those without CME had higher mean contrast sensitivity scores than those with CME; this increased over time. Those treated with flurbiprofen and indomethacin had slightly higher contrast sensitivity scores than vehicle-treated patients; this also increased over time, most notably in the higher spatial frequencies. Flurbiprofen treatment improved contrast sensitivity in patients with and without CME significantly at 12 cycles per degree. Flurbiprofen-treated patients with CME in general had higher contrast sensitivity scores than vehicle-treated patients. In this population of patients having cataract surgery, treatment with flurbiprofen or indomethacin reduced the loss of functional vision associated with CME.

Acute Disease↗
PubMed2002

Contrast sensitivity: establishing normative data for use in screening prospective naval pilots.

BACKGROUND: Contrast sensitivity testing can be a useful supplement to standard visual acuity tests. Currently there are no standards for contrast sensitivity in military aviation. Student naval pilots, who often have better-than-average visual acuity, could be expected to have better-than-average contrast sensitivity. Any attempt to establish contrast sensitivity standards for military aviation should begin with establishing normative data, particularly data gathered from the military aviation community. HYPOTHESIS: Student naval pilots differ from the general military population on Small Letter Contrast Test measurements. METHODS: Contrast sensitivity was measured in a group of student naval pilots (n = 107) and compared with results from aviation and non-aviation personnel. The Small Letter Contrast Test (SLCT) was used (19). Other subjects consisted of student naval flight officers (n = 40), experienced naval pilots and flight officers (n = 35 and 86, respectively), enlisted aircrew (n = 175), and other military personnel tested before undergoing photorefractive keratectomy (n = 185). RESULTS: Data collected provide large-group demographic characteristics and normative values for contrast sensitivity measured with the SLCT. Of the non-aviation controls, 95% scored at least 0.62 (read at least 7 lines plus 2 of 10 letters on the 8th line of the chart), and 95% of the student pilots scored at least 0.81, (read at least 9 lines plus 1 letter on the 10th line). CONCLUSION: Student naval pilots scored significantly better on the SLCT than the military control population. The SLCT shows potential as a screening device during induction physical examinations of military pilots.

Adult↗
PubMed2006

Contrast sensitivity and disability glare in patients with dry eye.

PURPOSE: To evaluate contrast sensitivity and disability glare in patients with dry eye using the Contrast Glaretester 1000. METHODS: Contrast sensitivity and disability glare were determined in 33 eyes of 33 patients with dry eye and 30 eyes of 30 healthy control subjects for six target sizes with a visual angle of 6.3-0.7 degrees using the Contrast Glaretester 1000, whose working mechanism is similar to that of the conventional perimetry instrument. RESULTS: Contrast sensitivity was significantly worse in dry eye group when viewing all target sizes (reduction of 0.10-0.25 log contrast units, p < 0.01) except at 6.3 degrees. In the presence of glare, differences in log contrast sensitivity between the groups (0.10-0.25 units) were significant (p < 0.01) for all target sizes, with the dry eye group showing worse results. The reduction in contrast sensitivity induced by glare (disability glare) was significantly worse in the dry eye group versus the control group but only for the 2.5-degree size target, where 0.14 log contrast units were lost. CONCLUSIONS: Contrast sensitivity with and without glare was significantly reduced in patients with dry eye compared with control subjects, but the number of log contrast units lost with glare (disability glare) was similar in the two groups, except for the 2.5-degree size target.

Adult↗
PubMed1995

[Transparency of intraocular lenses and contrast sensitivity].

A loss of contrast sensitivity was noted in patients with inciplent cataracts and also in artephakias. As all these patients displayed normal visual acuity (6/6-6/9), our data suggest that the use of high-contrast optotypes is insufficient. Low-contrast optotypes are recommended for testing visual acuity in the above mentioned groups of patients.

Aged↗
PubMed1993

[Modulation transfer function and contrast sensitivity of refractive multi-zone multi-focal lenses].

Contrast imaging of new multifocal intraocular lens (MIOL) designs with 5 and 7 refractive zones was examined by in vitro measurement of the modulation transfer function (MTF) and by testing contrast sensitivity with Regan 96% and 11% contrast sensitivity charts after "optical implantation" of MIOLs in 20 healthy subjects by means of a new optical device developed by Reiner. The results were compared with those obtained with a monofocal IOL and a diffractive MIOL. We found that the MTF of both refractive MIOLs showed a reduction in contrast at corresponding spatial frequencies compared with the monofocal and with the diffractive IOL, resulting in a Strehl ratio of below 30%. Contrast sensitivity after "optical implantation" was significantly reduced for the refractive 5- and 7-zone models in high contrast (Regan 96%), but for all MIOL models in low contrast (Regan 11%) compared with the monofocal IOL. The refractive 5-zone MIOL and diffractive MIOL showed no statistical difference in contrast sensitivity.

Contrast Sensitivity↗
PubMed2001

Corneal irregular astigmatism and contrast sensitivity after photorefractive keratectomy.

OBJECTIVE: To investigate the relation between contrast sensitivity and corneal irregular astigmatism in eyes after photorefractive keratectomy (PRK). DESIGN: Prospective observational case series. PARTICIPANTS AND CONTROLS: Seventy-nine eyes without corneal haze 6 months or more after PRK and 30 normal control eyes. METHODS: Videokeratography was taken with TMS-1 (Computed Anatomy Inc. New York, NY), and contrast sensitivity for day and night vision was measured using a Multivision Contrast Tester 8000 (Vistech Consultants, Inc., Dayton, OH). MAIN OUTCOME MEASURES: Regular and irregular astigmatism (asymmetry and higher order irregularity components) were computed using Fourier series harmonic analysis of the videokeratography data. Area under the log contrast sensitivity function (AULCSF) was calculated from the contrast sensitivity data taken at five spatial frequencies. RESULTS: After PRK, AULCSFs were significantly smaller for day vision (P = 0.007, unpaired t test) and night vision (P = 0.020) compared with normal controls. AULCSFs for day vision were significantly negatively correlated with asymmetry (Pearson's correlation coefficient, R = -0.23, P = 0.049) and higher order irregularity (R = -0.33, P = 0.004) components but not with the regular astigmatism component (P > 0.3). AULCSF for night vision correlated significantly with asymmetry (R = -0.31, P = 0.013) and higher order irregularity (R = -0.30, P = 0.016) components but not with the regular astigmatism component (P > 0.3). CONCLUSIONS: Corneal irregular astigmatism after PRK significantly influences contrast sensitivity.

Adult↗
PubMedDate not supplied

Visual contrast sensitivity testing: a comparison of two F.A.C.T. test types.

Measures of visual contrast sensitivity (VCS), rather than traditional measures of visual acuity using high-contrast stimuli, have been presented as better appraisals of visual dysfunction resulting from chemical exposures. The present study sought to determine if differences exist between two available measures of contrast sensitivity that use similar stimuli, specifically, a hand-held chart and an Optec 1000 vision tester. Monocular contrast sensitivity measures using both tests were obtained from 45 individuals as part of a NIOSH neurobehavioral test-battery appraisal. Test-retest reliability was found to be high for both the hand-held system and the Optec 1000 test (r=.750 and.773, respectively). In comparison to the automated test, the hand-held version produced statistically significant higher contrast sensitivity scores for lower spatial frequencies (1.5 and 3.0 cycles per degree) and lower scores for a relatively higher spatial frequency (18.0 cycles per degree [cpd]). Consequently, this study documents a difference in spatial frequency scores obtained with the hand-held form and Optec 1000 form of contrast sensitivity test, and attributes these differences to design characteristics affecting viewing. It is concluded that caution should be taken when making absolute comparisons of contrast sensitivity test scores between neurobehavioral studies that have used different forms of VCS testing.

Adult↗
PubMed1986

Contrast sensitivity in pseudophakia and aphakia.

Contrast sensitivity was measured in pseudophakic and aphakic patients. No difference could be demonstrated between the contrast sensitivities of patients with anterior chamber/iris-supported and posterior chamber intraocular lenses (IOLs). Little difference was found between pseudophakics and aphakics. Interocular contrast ratios in five pseudophakic patients with normal fellow eyes revealed a range of contrast attenuation characteristics which may be attributed to the IOL and corneal and posterior capsule transmission.

Adult↗
PubMed1986

Contrast sensitivity in amblyopia. IV. Assessment of vision using vertical and horizontal gratings and optotypes at different contrast levels.

The contrast sensitivity of 49 amblyopic children (mean age 9 years) was measured in the beginning and at the end of a treatment period using both vertical gratings and optotypes (LH-4 contrast test) at 2, 3, 5 and 75% contrast. The contrast sensitivity of 37 patients was also measure using horizontal gratings. The contrast sensitivity of the dominant eyes measured with vertical gratings was generally higher than when measured with horizontal gratings. The difference was statistically significant at spatial frequencies 1 and 6 c/deg. A similar difference was present in the amblyopic eyes only at the spatial frequency 1 c/deg both before and after the treatment. Individual variation was great; in a given patient the relationship between the two measurements varied from one spatial frequency to the next. It has been shown in earlier investigations that contrast sensitivity measurements using gratings reveal important new information in the study of amblyopia. Both tests, used in this investigation, measure visual function in the low contrast domain and improve follow-up of the changes in vision during treatment of amblyopia when used in addition to visual acuity measurements. Low contrast optotype test seems to measure contrast sensitivity in amblyopia closely similarly to the grating test. The slight difference in detecting a 'hidden occlusion amblyopia' at the intermediate spatial frequencies needs further study.

Adolescent↗