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Results for “Contrast Sensitivity”

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PubMed1999

Losses of hemifield contrast sensitivity in patients with pituitary adenoma and normal visual acuity and visual field.

OBJECTIVE: To detect early losses of contrast sensitivity (CS) in patients with pituitary adenomas, before the occurrence of visual acuity and visual field defects. METHODS: CS has been evaluated in both hemifields of 28 patients with different kinds of pituitary adenoma (mainly intrasellar) and normal visual acuity and visual field, as well as in 15 age-matched controls. Two different stimuli were used: a coarse (0.3 c/deg) dynamic (10 Hz) grating and a finer (2 c/deg) static grating. RESULTS: On average, CS and/or hemifield asymmetry were reduced in patients, whereas perimetric sensitivity was normal. CS losses were more frequent for 2 c/deg static-, as compared with 0.3 c/deg, 10 Hz stimuli. However selective losses for either stimuli were also found. CS losses did not correlate with anatomical measurements (size, chiasm involvement) of tumors as established by MRI scans. CONCLUSIONS: CS evaluation may provide a simple and effective tool for early detection and monitoring of visual dysfunction in patients with pituitary adenoma. The lack of correlation between CS losses and chiasm involvement suggests causes different from chiasmal compression for visual dysfunction.

Adenoma↗

PubMed1983

Spatial contrast sensitivity changes after subcortical visual system lesions in the rat.

Spatial contrast sensitivity functions were determined in hooded rats after lesions involving the pretectum (PRT), rostral pretectum and adjacent medial thalamus (PRT +), posterior thalamus (PT), or ventral lateral geniculate nucleus (LGv). PRT and PRT + lesions depressed sensitivity at both high and low spatial frequencies but the high frequency loss was much greater in the latter group. PT lesions depressed sensitivity to frequencies of 0.45 cycles/deg. and above but had no detectable effect upon low frequencies while LGv lesions depressed sensitivity to both high and low frequencies. The discussion relates these results to previous reports of discrimination learning impairments after comparable lesions.

Animals↗

PubMed1982

Contrast sensitivity measurement in retinal diseases by laser generated sinusoidal grating.

The contrast sensitivity function (CSF) of 83 patients with retinal diseases was measured by laser-generated sinusoidal grating pattern, which enables the direct measurement of the CSF between the retina and the brain. The CSF abnormality in various retinal diseases was not specific to each disease, and the severity may determine the pattern. The abnormal patterns and rough correlation with visual acuity (V.A.) are: (1) attenuation at high frequency ranges (V.A. greater than 0.8), (2) attenuation at intermediate and high frequency ranges (0.4 less than V.A. less than 0.7), (3) attenuation at all frequency ranges (V.A. less than 0.3). Some cases, however, showed discrepancy between visual acuity and CSF. At the recovery stage of central serous retinopathy and retinal branch vein occlusion, CSF showed delayed recovery or attenuated sensitivity even when visual acuity was restored to 1.0 or more. In retinitis pigmentosa and pre-retinal macular fibrosis, CSF showed more sensitive detection of abnormal macular function than visual acuity measurement. At the post-corticosteroid therapy of Harada's disease and Sympathetic Ophthalmia, CSF recovered more rapidly than visual acuity when retinal detachment was absorbed. Those discrepancies suggest that CSF measurement may be useful for evaluating progression or regression of these diseases.

Adolescent↗

PubMedDate not supplied

Contrast sensitivity functions in normal children with the Vistech method.

The Vistech Contrast Sensitivity Function tester (VCTS 6500-1) for distance was evaluated to determine the minimum age of children who could complete the test and to determine changes in the CSF as a function of age. A total of 72 normal children between the ages of 24 and 84 months were tested twice with each eye. The results revealed that no child below 36 months of age could complete the test and by 48 months of age 50% could complete the test. By 60 months all children could complete the test. It was also found that age increased the CSF increased equally at all spatial frequencies. A comparison between the eyes of the CSFs revealed a highly statistically significant correlation of 0.78, which showed that the eyes were very similar. Test-retest correlations (0.78) also were highly statistically significant, which demonstrated that the test was very reliable. The results are discussed within the context of screening young children for visual disorders and the evaluation of patching therapy for amblyopia.

Child Development↗

PubMed2004

Clinical testing of contrast sensitivity in children: age-related norms and validity.

PURPOSE: The Hiding Heidi (HH) test and the LEA low-contrast symbols are two commercially available charts of contrast sensitivity (CS) for children. However, there are no published normal data and no indication of how CS measured by these charts relates to other measures of CS. In this study, normal age-related data for both tests are reported, and validity against the Pelli-Robson (PR) chart is measured. METHODS: Eighty-eight normally sighted children were divided into four age groups: 1 to <2.5 years, 2.5 to <4 years, 4 to <6 years, and 6 to <8 years. An adult group with normal vision and with low vision also took part. CS was measured with the HH test, the LEA symbols at 1 m and 28 cm, and the PR chart, as the child's ability permitted. Because there were obvious differences between the contrast levels of the PR chart and the nominal contrast for the children's charts, each contrast level for the children's tests was recalibrated. RESULTS: The HH test and the LEA symbols at 28 cm and 1 m all showed a floor effect; that is, most children of all ages correctly responded to the lowest contrast. The median CS for the LEA symbols at 28 cm and 1 m was 2.22 log CS, which was 1.65 when recalibrated. There was a significant difference of PR CS between the 6- to <8-year-olds and adults (p < 0.001). Of the children's charts, the LEA symbols at 28 cm, once recalibrated for contrast, had the best agreement with the PR chart. CONCLUSION: The LEA and HH charts cannot measure a true contrast threshold for children with normal vision because of the floor effect. The LEA symbols at 28 cm gave the most useful information, once recalibrated for contrast, and may be useful to predict performance of children with low vision, when CS is likely to be compromised.

Adult↗

PubMed1994

[Objective evaluation of visual strain in computer screen and office work by recording visually evoked cortical potentials (VECP) and determining changes in contrast sensitivity and refraction].

Visual evoked cortical potentials (VECP) elicited with checkerboard pattern reversal stimuli of high spatial frequency and low contrast were recorded. The changes in the VECP depending on the duration of task-oriented activity at video display units (VDU) and in the office were determined. The testing procedure can be used to decide on adequate recovery periods (breaks) for any visual workload and requires only a short time. We investigated 30 probands: 10 subjects tested before and after 4 h of VDU work under controlled standard conditions had statistically significant increases of latency (P < 0.001) and decreases of amplitude in VECP recordings (P < 0.05). Another 10 subjects tested at the same intervals but exposed to standard office working conditions also showed statistically significant increases of latency (P < 0.0001) and decrease of amplitude in VECP recordings (P < 0.01). The 10 control subjects tested at the same intervals spent the time between recording sessions on leisure activity (walking) and showed no significant VECP changes. Statistical evaluation was performed with Student's t-test for paired samples. Contrast sensitivity (Ginsburg test) decreased in both VDU and office groups after completion of their workload, but remained within normal limits. The maximal changes in refraction amounted to +/- 0.25 D after 4 h and +/- 0.5 D after 6 h and showed no bias. Extended periods of working at VDUs and conventional office work increase the latency and decrease the amplitude of the pattern-evoked VECP. This method can be used to determine optimal scheduling of breaks in for people working at VDUs and doing conventional office work.

Adult↗

PubMed2005

Subclinical visual involvement in multiple sclerosis: a study by MRI, VEPs, frequency-doubling perimetry, standard perimetry, and contrast sensitivity.

PURPOSE: To evaluate the effectiveness of visual evoked potentials (VEPs), frequency-doubling perimetry (FDP), standard achromatic perimetry (SAP), contrast sensitivity (CS) test, and magnetic resonance imaging (MRI), isolated or in combination, in detecting subclinical impairment of visual function in multiple sclerosis (MS). METHODS: Twenty-two eyes of 11 patients affected by clinically definite MS, without a history of optic neuritis and asymptomatic for visual disturbances, underwent full ophthalmic examination and, in addition, VEPs, FDP, SAP, CS, and MRI. Abnormal results were taken to be as follows: for VEPs, a P100 latency >115 ms; for FDP, abnormal mean deviation (MD) or pattern SD (PSD); for SAP, abnormal MD or PSD; for CS, abnormal CS at one spatial frequency, at least; and for MRI, evidence of at least one demyelinating plaque along the visual pathway. RESULTS: VEPs showed abnormal results in 12 eyes (54.4%), FDP in 11 (50%), SAP in 14 (63.6%), CS in 17 (77.1%), and MRI in 16 (72.7%). In only two (9.1%) eyes of the same patient was no abnormality found. No single test detected all the abnormal eyes. Four (18.2%) eyes had pure optic nerve involvement and the remaining 16 (72.7%) had both pre- and postchiasmal involvement. CONCLUSIONS: In patients affected by clinically definite MS without history of optic neuritis and no visual symptoms, there is a large prevalence of visual pathway involvement that can be diagnosed only by performing multiple tests. The comparison of the tests is also useful to detect the presence of multiple lesions in the same patient.

Adolescent↗

PubMed1997

Pattern electroretinogram and spatial contrast sensitivity in primary congenital glaucoma.

OBJECTIVE: The authors investigated the temporal and spatial characteristics of pattern electroretinogram (PERG) and spatial contrast sensitivity (CS) in primary congenital glaucoma (PCG) to determine whether the PERG and CS could be useful tools in the diagnosis of childhood glaucoma, especially PCG. PARTICIPANTS: The PERGs were evaluated in eyes from ten patients with PCG and nine age-matched visually normal subjects. INTERVENTION: All patients received complete ophthalmologic evaluations including visual field testing. MAIN OUTCOME MEASURES: The PERGs were recorded using phase-alternating (2, 4, and 16 reversals per second [rps]) checkerboard patterns (30' and 60' checks). RESULTS: The patients with PCG exhibited decreased CS when compared with that of control subjects. Significant PERG deficits also were detected in these patients. However, PERG amplitude in patients with PCG almost reached control subject levels at high (16 rps) temporal frequency. This was true for both 30' and 60' checks. Taken together, these observations on PERG amplitude suggest a more important deficiency of the neural response of the retinal cells at lower temporal frequency (rps) in patients with PCG. This is unlike primary open-angle glaucoma (POAG) in which significant PERG deficits are observed at high temporal frequencies. CONCLUSIONS: The PERG amplitude is reduced in patients with PCG, and this is consistent with a loss of CS and visual field changes in these patients. However, the spatiotemporal characteristics of the PERG deficits in PCG differ from those of POAG. This could suggest a difference in the mechanisms mediating retinal ganglion cell dysfunction in the two types of glaucoma.

Adolescent↗

PubMed2006

The letter contrast sensitivity test: clinical evaluation of a new design.

PURPOSE: To compare the reliability, validity, and responsiveness of the Mars Letter Contrast Sensitivity (CS) Test to the Pelli-Robson CS Chart. METHODS: One eye of 47 normal control subjects, 27 patients with open-angle glaucoma, and 17 with age-related macular degeneration (AMD) was tested twice with the Mars test and twice with the Pelli-Robson test, in random order on separate days. In addition, 17 patients undergoing cataract surgery were tested, once before and once after surgery. RESULTS: The mean Mars CS was 1.62 log CS (0.06 SD) for normal subjects aged 22 to 77 years, with significantly lower values in patients with glaucoma or AMD (P<0.001). Mars test-retest 95% limits of agreement (LOA) were +/-0.13, +/-0.19, and +/-0.24 log CS for normal, glaucoma, and AMD, respectively. In comparison, Pelli-Robson test-retest 95% LOA were +/-0.18, +/-0.19, and +/-0.33 log CS. The Spearman correlation between the Mars and Pelli-Robson tests was 0.83 (P<0.001). However, systematic differences were observed, particularly at the upper-normal end of the range, where Mars CS was lower than Pelli-Robson CS. After cataract surgery, Mars and Pelli-Robson effect size statistics were 0.92 and 0.88, respectively. CONCLUSIONS: The results indicate the Mars test has test-retest reliability equal to or better than the Pelli-Robson test and comparable responsiveness. The strong correlation between the tests provides evidence the Mars test is valid. However, systematic differences indicate normative values are likely to be different for each test. The Mars Letter CS Test is a useful and practical alternative to the Pelli-Robson CS Chart.

Adult↗

PubMed1993

Contrast sensitivity in patients with keratoconjunctivitis sicca before and after artificial tear application.

Poor stability of the precorneal tear film causes dry eye symptoms and has detrimental effects on the optical function of the eye. In 50 patients with dry eyes the local instillation of artificial tears significantly improved contrast sensitivity (P < 0.001), using the Vision Contrast Test System 6500. In the untreated eyes no significant changes were found to occur (P = 0.56).

Aged↗

PubMed2003

Senescent effects on binocular summation for contrast sensitivity and spatial interval acuity.

PURPOSE: Age effects on binocular summation, a cortically mediated visual function, were compared for resolution acuity, contrast sensitivity (CS), and spatial interval (SI) hyperacuity. METHOD: The binocular and monocular thresholds of healthy, optimally-corrected healthy young (mean age 21.3 years) and old (mean age 69.9 years) observers were determined for acuity, SI discrimination, and CS at 1.0, 2.0, 4.0, 8.0 and 18.0 c/deg. RESULTS: No age effects were observed on monocular or binocular SI discrimination. The binocular summation ratios (BSRs) did not exceed the expected probability gain for resolution acuity or SI discrimination in either age group. Older observers showed a binocular inhibition effect on the SI task. On the CS task, the BSRs of the young significantly exceeded those of the old only at 18.0 c/deg. CONCLUSIONS: 1.) Binocular summation of high spatial frequency contrast information, which may be less robust in the senescent visual system, did not appear to be related to interocular CS differences, 2.) SI discrimination of high contrast, well-separated targets appears to be unaffected by aging, and 3.) Binocular neural summation on SI discrimination may be more likely to be seen with targets that are narrowly separated or low in contrast.

Adolescent↗

PubMed1992

[Contrast sensitivity study in the fellow eyes of patients with central serous chorioretinopathy].

In clinical practice, it has been shown that the contrast sensitivity (CS) test is one of the most sensitive visual functional tests. In our experiment, we used a U.S.-made VCTS 60000 CS test plate to test the fellow eyes (20) of 20 cases with unilateral central serous chorioretinopathy (CSC), along with age-matched normal controls. From the control group, we obtained a group of bell-shaped normal CS curves which showed some degree of decrease with age. 40% of the fellow eyes of the patient group showed a slight CS decrease at mid-high spatial frequencies, though other visual functional tests show no abnormality. These fellow eyes may be at risk for CSC. Our experiment, for the first time, showed the possibility of using the CS test as a diagnostic test for subclinical CSC.

Adult↗

PubMed2006

Accuracy of the contrast sensitivity card test for infants: retest variability and prediction of spatial resolution.

PURPOSE: We assessed the retest variability of a new contrast sensitivity (CS) card procedure and its ability to predict spatial resolution. METHODS: Twenty-four 3-month-olds were tested twice with the CS cards and once with the Teller acuity cards (TAC) within a single session. RESULTS: Coefficient of repeatability (COR) analysis revealed that retest variability of the new cards is superior to that of an earlier prototype at low to mid spatial frequencies. Furthermore, retest variability is comparable to that of infant visual evoked potential studies and the Vistech 6500, a chart commonly used to measure CS in adults. Finally, estimates of visual acuity based on the CS cards were consistent with those provided by the TAC (although CS-based estimates were generally lower overall). CONCLUSIONS: Given its reliability and accuracy, the new CS card procedure has good potential as a clinical tool for assessing spatial vision in infants and toddlers.

Contrast Sensitivity↗

PubMed2000

The effect of bilberry nutritional supplementation on night visual acuity and contrast sensitivity.

PURPOSE: The purpose of this study was to investigate the effect of bilberry on night visual acuity (VA) and night contrast sensitivity (CS). METHODS: This study utilized a double-blind, placebo-controlled, crossover design. The subjects were young males with good vision; eight received placebo and seven received active capsules for three weeks. Active capsules contained 160 mg of bilberry extract (25-percent anthocyanosides), and the placebo capsules contained only inactive ingredients. Subjects ingested one active or placebo capsule three times daily for 21 days. After the three-week treatment period, a one-month washout period was employed to allow any effect of bilberry on night vision to dissipate. In the second three-week treatment period, the eight subjects who first received placebo were given active capsules, and the seven who first received active capsules were given placebo. Night VA and night CS was tested throughout the three-month experiment. RESULTS: There was no difference in night VA during any of the measurement periods when examining the average night VA or the last night VA measurement during active and placebo treatments. In addition, there was no difference in night CS during any of the measurement periods when examining the average night CS or the last night CS measurement during active and placebo treatments. CONCLUSION: The current study failed to find an effect of bilberry on night VA or night CS for a high dose of bilberry taken for a significant duration. Hence, the current study casts doubt on the proposition that bilberry supplementation, in the forms currently available and in the doses recommended, is an effective treatment for the improvement of night vision in this population.

Adult↗

PubMed1993

Notch in contrast sensitivity function of optical origin: diffraction effects of acrylic filters.

A series of retinal image degrading filters was evaluated by measuring the contrast sensitivity function of four human subjects through the filters (residual CSF). The acrylic filters, with regularly spaced cross-hatches, produced progressively more reduction in the residual CSF as the density of the cross hatching increased. For some of the filters there was a selective loss of a narrow band of spatial frequencies as a result of diffraction effects. This experiment serves to further emphasize the need to rule out optical causes of such notches in the CSF before making a diagnosis of neurological dysfunction.

Acrylic Resins↗

PubMed1999

Functional vision and corneal changes after laser in situ keratomileusis determined by contrast sensitivity, glare testing, and corneal topography.

PURPOSE: To demonstrate the functional vision and corneal changes following laser in situ keratomileusis (LASIK) determined by contrast sensitivity, glare testing, and corneal topography. SETTING: University of Texas Medical School, Houston, Texas, USA. METHODS: Seven patients ranging in age from 20 to 61 years who had bilateral LASIK were evaluated preoperatively and 1 day, 1 week, and 1 and 6 months postoperatively. Visual acuity, using letters on the Baylor Visual Acuity Testor (BVAT) at 98% (standard acuity) and 13% contrast, and the contrast threshold were determined at 3 light levels (darkness, medium brightness acuity testor [BAT], high BAT). Pupil sizes were measured at each level, and corneal topography was performed at each visit. RESULTS: The greatest changes were found 1 day postoperatively: The contrast threshold worsened by a mean of 0.6 lines +/- 1.0 (SD) (P = .05) in darkness, 0.4 +/- 0.7 lines (P = .05) at medium BAT, and 0.8 +/- 0.7 lines (P = .002) at high BAT. The 98% contrast acuity decreased a mean of 1.4 +/- 1.6 lines (P = .01) in darkness, 1.0 +/- 2.0 lines (P = .09) at medium BAT, and 0.8 +/- 2.3 lines (P = .22) at high BAT. The 13% contrast acuity decreased a mean of 2.2 +/- 2.6 lines (P = .01) in darkness, 1.3 +/- 1.9 lines (P = .02) at medium BAT, and 1.4 +/- 2.5 lines (P = .07) at high BAT. The predicted corneal acuity (PCA) obtained from corneal topography decreased by a mean of 3.3 +/- 3.1 lines (P = .002), and the asphericity (Q-value) increased by an average of +0.35 +/- 0.67 (P = .07). All values returned to the preoperative levels by 1 week except PCA, asphericity, visual acuity at 13%, and contrast threshold in darkness, which improved slightly but had not returned to baseline by 6 months. The 98% contrast acuity at medium BAT improved by 0.2 +/- 1.0 lines (P = .34) and 0.3 +/- 0.8 lines (P = .16) at high BAT at 1 month. The 98% contrast acuity values remained 0.3 lines over baseline through 6 months. Corneal topography showed that all corneas became oblate after LASIK to a mean Q-value of +0.47 +/- 0.40 (P = .0001) and PCA was decreased by 1.6 +/- 1.1 lines (P = .0002) at 6 months. CONCLUSIONS: Functional vision changes do occur after LASIK. The optical quality of the cornea is reduced and the asphericity becomes oblate. Changes in functional vision worsen as the target contrast diminishes and the pupil size increases. These findings indicate that the oblate shape of the cornea following LASIK is the predominant factor in the functional vision decrease.

Adult↗

PubMed2004

Simulated impairment of contrast sensitivity: performance and gaze behavior during locomotion through a built environment.

PURPOSE: An experimental study investigated the effects of simulated impairment of contrast sensitivity (CS) on performance and eye gaze patterns during locomotion through a library. METHOD: Normally sighted participants with simulated CS impairment (diffusive blur) walked two routes, one entailing limited change in direction (simple) and the other entailing several changes in direction (complex), while eye movements relative to the scene were recorded. Performance variables included walking speed in completing the route, pauses during travel, and collisions with objects on the route. For eye movements, dwell time and saccades were determined for each of three object classes: (1) objects on the route below eye level; (2) objects on the route extending above eye level; and (3) elsewhere-objects not on the route. RESULTS: Walking speed was significantly affected by CS level and by route; pauses and collisions were rare. Dwell times and saccades suggested limited attention directed to low-level objects, except for CS impairment on the complex route. In the complex route, saccades and dwell times in the object class "elsewhere" were also reduced. CONCLUSIONS: The results for the simple route suggest ballistic strategies: the participant appraises the scene and follows a more or less predetermined path. For the complex route, CS impairment appears to adversely affect information processing and locomotion. The results have implications for the design of built environments, especially with regard to the safety of visually impaired occupants during emergency scenarios.

Adult↗

PubMed1992

[Contrast sensitivity and glare].

The ability of the visual system to detect the information presented to the eye in form of spatial or temporal contrast can be characterized by the contrast sensitivity function (CSF). CSF measurements can be used to visualize loss in visual capacity in patients with different diseases and to monitor recovery of vision. In the clinic CSF is most commonly used to evaluate disability glare in patients with cataract.

Adaptation, Ocular↗