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PubMed1988

Impaired visual contrast sensitivity in epileptic patients treated with carbamazepine.

Critical flicker fusion frequencies and visual contrast sensitivity were determined in 27 adult epileptic patients receiving carbamazepine monotherapy and in 24 healthy, drug-free control subjects. Flicker fusion thresholds were the same in patients and control subjects, whereas the contrast sensitivity was significantly reduced in the patient group at all spatial frequencies. There was a significant negative correlation between the plasma concentration of carbamazepine and the contrast sensitivity at 11.4 and 22.8 cycles per degree, indicating that the reduced contrast sensitivity was due to the drug therapy.

Adolescent↗
PubMed2005

Changes in contrast sensitivity after Artisan lens implantation for high myopia.

PURPOSE: To determine the effects of Artisan lens implantation on contrast sensitivity. DESIGN: Prospective consecutive interventional case series. PARTICIPANTS AND CONTROLS: Forty-nine eyes of 30 patients with myopia and myopia with astigmatism, who underwent implantation of the Artisan iris-fixated phakic intraocular lens. Preoperative testing served as the control. INTERVENTION: Implantation of the Artisan phakic intraocular lens to correct myopia. MAIN OUTCOME MEASURES: Refractive predictability and Snellen visual acuity were evaluated preoperatively and at least 4 months postoperatively. Additionally, photopic and mesopic contrast sensitivities were measured at 1.5, 3, 6, 12, and 18 cycles per degree, with and without glare testing. RESULTS: The mean preoperative spherical equivalent (SE) was -12.16 diopters (D) (range, -6.88 to -18.00). The mean postoperative SE was -0.46+/-0.58 D (range, +0.50 to -1.75). Ninety percent of eyes were within 1.00 D of the predicted result, and 39% gained > or =1 lines of best-corrected visual acuity (BCVA). When compared with preoperative measurements, postoperative contrast sensitivity was increased under photopic conditions and slightly decreased under mesopic conditions. Adverse events were one wound leak requiring resuturing in the immediate postoperative period and one subluxed lens after significant blunt trauma. No eyes lost > or =2 lines of BCVA. CONCLUSIONS: Artisan implantation for the correction of high myopia seems to be a predictable procedure. Increases in photopic contrast sensitivity values after implantation of this phakic intraocular lens stand in distinction to the decreases in photopic contrast sensitivity previously reported after LASIK correction of this degree of myopia.

Adult↗
PubMed1986

Contrast sensitivity during provoked visual impairment in multiple sclerosis.

Many patients with multiple sclerosis have subjective visual complaints that are intensified by exercise (Uhthoff's symptom). We report a case demonstrating the utility of contrast sensitivity testing in such visual complaints. Contrast sensitivity was measured before and after exercise in a multiple sclerosis patient with Uhthoff's symptom and in two healthy control subjects. A short exercise period reduced the patient's contrast sensitivity for some target sizes, but had no effect on his visual acuity; a longer exercise period produced a greater, more uniform loss of contrast sensitivity and also reduced visual acuity. Contrast sensitivities and visual acuities of the control subjects were not affected by exercise.

Adult↗
PubMed1996

Pelli-Robson contrast sensitivity test in Zaire.

The purpose of this study was to establish in this first report the age standards of the Pelli-Robson contrast sensitivity in Zaïre. Contrast sensitivity using the Pelli-Robson chart was performed in 100 normal Zairian black subjects aged from 10 to 59 years and 36 patients (22 patients with open-angle glaucoma and 14 with optic nerve disease). Scores of normal subjects were age related (p < 0.05). The results of Zairian young subjects were similar to those found previously in young white subjects; scores for older subjects were lower when compared to those of whites. Scores of patients were lower than those of normals (p < 0.001). Contrast sensitivity using the Pelli-Robson chart can be useful in developing countries.

Adolescent↗
PubMed1981

Reduced contrast sensitivity in compressive lesions of the anterior visual pathway.

A clinical procedure for determining contrast sensitivity was performed on patients with suspected sella area masses. The test consisted of a series of six plates, each containing a bar pattern of fixed sinusoidal spatial frequency in which contrast varies along the length of the bar. Patients with compressive lesions of the chiasm of optic nerve showed loss of contrast sensitivity over the whole range of spatial frequencies. The general loss in contrast was evident even in patients with 20/20 Snellen acuity. After surgery, contrast sensitivity improved, as did other measures of vision, but significant contrast deficits remained. Contrast sensitivity is a sensitive indicator for the diagnosis and evaluation of compressive lesions of the chiasm.

Adult↗
PubMed2004

Induced aniseikonia diminishes binocular contrast sensitivity and binocular summation.

PURPOSE: To study the effect on binocular contrast sensitivity and binocular summation of aniseikonia induced by size (afocal) lenses. METHODS: In 18 young emmetropic observers, the monocular and binocular contrast sensitivity function was measured under normal conditions and after inducing different degrees of aniseikonia (2%, 3%, and 5% and for 6 observers, 8%) in the right eye. The spatial frequencies tested were 2.4, 3.7, 6.0, 9.2, 12, 15, 20, and 24 cpd. RESULTS: The results reveal a significant decline in binocular contrast sensitivity and binocular summation for 5% aniseikonia, this decline being more pronounced for intermediate and high spatial frequencies. CONCLUSIONS: These results, together with others on different binocular functions, show the importance of aniseikonia in binocular vision. On this basis, we recommend that aniseikonia be considered in surgical processes such as cataract and refractive surgery, whereby aniseikonia could be induced and binocular performance subsequently diminished.

Adolescent↗
PubMed2000

Prediction of letter contrast sensitivity using videokeratographic indices.

PURPOSE: To analyze the relationship between corneal topography and letter contrast sensitivity. METHOD: Experiments were conducted on 59 eyes of 51 patients who had best spectacle-corrected visual acuity of 20/20 or better and no ocular pathology except for the corneal shape. Thirty-nine eyes had an abnormal topographic pattern resulting from keratoconus, and the other 20 eyes showed a normal topographic pattern. Videokeratography was performed with the TMS-2 videokeratoscope, and the surface regularity index, surface asymmetry index, and coefficient of variation of power were obtained for each subject. Letter contrast sensitivity was measured with the CSV-1000LV with spectacle correction. The correlation between the number of correct letters and topographic indices was calculated. RESULTS: The abnormal topography group had a significantly greater loss of letter contrast sensitivity (median = 20 letters) than the normal control (median = 23 letters; P =.0001). There were statistically significant correlations between number of correct letters and the coefficient of variation of power (r = -.77; P =. 001), number of correct letters and surface regularity index (r = -. 76, P =.001), and the number of correct letters and surface asymmetry index (r = -.64; P =.001). The linear regression equation between number of correct letters and the coefficient of variation of power was the number of correct letters = -0.05 x the coefficient of variation of power + 23.2. CONCLUSIONS: Our results suggest that subtle visual deteriorations, which are barely detected by contrast sensitivity testing, can be predicted objectively by the corneal topographic indices.

Adult↗
PubMed1999

Assessment of contrast sensitivity in children aged 3 years 9 months - 6 years with normal vision, visual impairment due to ocular disease and strabismic amblyopia.

The contrast sensitivity function was assessed in children and adults with normal vision, visual impairment due to ocular disease, and strabismic amblyopia. The methods used were: the LH contrast vision test and the ability to detect raisins, puffed rice and white and black sugar strands against a white and black background. The aim of the study was to see whether any of the tests could be used in the detection of subnormal vision, and to compare the results between the different groups of patients. The following parameters of contrast sensitivity function (CSF) were measured with the LH-test: the maximum contrast sensitivity, the total area of CSF, and the area of 8 spatial frequency bands. Difficulty in detecting an object with low versus high contrast was measured with the sugar strands. Subjects with subnormal vision due to ocular disease and strabismic amblyopia had lower contrast sensitivity than subjects with normal vision measured as the total area of the CSF or the area of a specific frequency band. However, the maximum contrast sensitivity value that could be measured with the test was not significantly different between the groups. No subject had difficulties in the detection of raisins and puffed rice on a white and black background. Difficulties in detecting sugar strands on a white background were not seen in the normal children, but approximately 65% of the children with visual impairment had difficulties, as did approximately 25% of the children and adults with strabismus. Most of these subjects also had low visual acuity, but there was no correlation between the level of reduction of visual acuity and the difficulty in detecting sugar strands.

Adult↗
PubMed1989

Spatial contrast sensitivity in unilateral cerebral ischaemic lesions involving the posterior visual pathway.

Contrast sensitivity function was studied in 16 patients with unilateral ischaemic lesions involving the posterior visual pathway. Sixty-two percent of the patients showed contrast sensitivity loss in at least one eye for horizontal or vertical stimulus orientation. Visual perception was distorted in a qualitatively different way according to the anteroposterior site of the lesion. Patients with occipital or occipitotemporal lesions showed high spatial frequency selective losses and patients with temporal or parietal lesions low frequency selective losses. Stimulus orientation selectivity was observed in patients with lesions of the primary visual cortex as well as in patients with lesions anterior to the striate cortex. Contrast sensitivity orientation-selective losses were demonstrated in 14 of the 17 'affected' eyes.

Aged↗
PubMed1985

The contrast sensitivity of human colour vision to red-green and blue-yellow chromatic gratings.

A method of producing red-green and blue-yellow sinusoidal chromatic gratings is used which permits the correction of all chromatic aberrations. A quantitative criterion is adopted to choose the intensity match of the two colours in the stimulus: this is the intensity ratio at which contrast sensitivity for the chromatic grating differs most from the contrast sensitivity for a monochromatic luminance grating. Results show that this intensity match varies with spatial frequency and does not necessarily correspond to a luminance match between the colours. Contrast sensitivities to the chromatic gratings at the criterion intensity match are measured as a function of spatial frequency, using field sizes ranging from 2 to 23 deg. Both blue-yellow and red-green contrast sensitivity functions have similar low-pass characteristics, with no low-frequency attenuation even at low frequencies below 0.1 cycles/deg. These functions indicate that the limiting acuities based on red-green and blue-yellow colour discriminations are similar at 11 or 12 cycles/deg. Comparisons between contrast sensitivity functions for the chromatic and monochromatic gratings are made at the same mean luminances. Results show that, at low spatial frequencies below 0.5 cycles/deg, contrast sensitivity is greater to the chromatic gratings, consisting of two monochromatic gratings added in antiphase, than to either monochromatic grating alone. Above 0.5 cycles/deg, contrast sensitivity is greater to monochromatic than to chromatic gratings.

Color Perception↗
PubMed2005

Improvement of spatial contrast sensitivity threshold after surgical reduction of intraocular pressure in unilateral high-tension glaucoma.

PURPOSE: To measure the effect of a surgical reduction of IOP on the spatial contrast sensitivity threshold in eyes showing a considerably increased IOP but no glaucomatous visual field defect, on white-on-white computer-assisted static perimetry. METHODS: Prospective clinical trial, lasting 36 months; 10 consecutive subjects with untreated IOP > or = 30 mmHg in one eye and < or =18 mmHg in the fellow eye, no evidence of field damage in both eyes, best corrected visual acuity > or =20/20 in both eyes, and scheduled for a primary trabeculectomy in the eye showing a high IOP. The spatial contrast sensitivity threshold was measured before surgery and at each follow-up visit. RESULTS: Preoperative spatial contrast sensitivity was worse in those eyes bearing a high IOP relative to the normal fellow eyes (paired samples t-test, P <0.0005). An improvement of contrast sensitivity threshold, exceeding the 95% confidence limits of the preoperative test-retest variability, was observed at 3, 6, and 12 cyc/deg in each surgical eye at the end of follow-up. No change was observed in the fellow untreated normal eyes. The improvement correlated directly with the amount of decrease in pressure obtained by surgery. CONCLUSIONS: Eyes with no field defects on white-on-white computer-assisted static perimetry, but bearing a IOP > or = 30 mmHg, show a decreased spatial contrast sensitivity. A surgically obtained reduction of IOP is paralleled by an improvement of spatial contrast sensitivity.

Adult↗
PubMed1991

Spatial contrast sensitivity is reduced in bilateral Parkinson's disease.

We studied the contrast sensitivity functions of 41 patients with idiopathic Parkinson's disease (PD) with a wide range of parkinsonian symptomatology (Hoehn and Yahr stages 1 to 4) and 22 age-matched control subjects in a parametric design. Results demonstrated reduced contrast sensitivity in PD patients but only in those patients who had progressed beyond Hoehn and Yahr stage 1. Furthermore, there were deficits in contrast sensitivity related to the severity of PD.

Aged↗
PubMed1996

Hyperoxia improves contrast sensitivity in early diabetic retinopathy.

AIM: The cause of vascular and visual pathology in diabetic retinopathy remains unknown. If retinal hypoxia plays a role, then early in the course of diabetes 100% oxygen breathing should normalise both contrast sensitivity and retinal blood flow. METHODS: This hypothesis was tested in 12 diabetic patients with minimal retinopathy who, none the less, exhibited reduced contrast sensitivity (p = 0.003 versus 12 age and sex-matched controls) and prolonged retinal arteriovenous dye transit (p = 0.0001 versus controls). RESULTS: Isocapnic hyperoxia failed to alter contrast sensitivity in controls, while it significantly improved contrast sensitivity in patients (at 12 cpd; p = 0.042) to levels indistinguishable from normal. Individual improvement in contrast sensitivity correlated positively with the severity of the initial defect (r = +0.84, p = 0.0008). Hyperoxia also had haemodynamic effects; it slowed retinal arteriovenous passage of fluorescein dye in controls, but did not further slow this transit time in patients. CONCLUSIONS: These results demonstrate the reversibility of early contrast sensitivity deficits in diabetes mellitus, and support the hypothesis that factors linked to tissue hypoxia initiate both visual and vascular dysfunction in diabetic retinopathy.

Adult↗
PubMed1991

Detection of hidden visual loss in multiple sclerosis. A comparison of pattern-reversal visual evoked potentials and contrast sensitivity.

The detection of hidden visual loss is important in establishing the diagnosis of multiple sclerosis, especially in patients who have neurologic symptoms of the disease. Both visual evoked potentials and contrast sensitivity have been used for this purpose. We compared the sensitivities of pattern-reversal visual evoked potentials and contrast sensitivity, measured with the Vistech VCTS 6500 chart, in detecting hidden visual loss in 18 patients with multiple sclerosis whose visual acuity was correctable to 20/20 (6/6) or better in the examined eye. Thirteen patients had delayed visual evoked potential latencies. An additional four patients had reduced P100 amplitudes without prolonged latencies. Nine patients had abnormal contrast sensitivity. The visual evoked potential was more sensitive than contrast sensitivity at detecting hidden visual loss in patients with multiple sclerosis (p less than 0.01).

Adult↗
PubMed2006

Determinants of health related quality of life and health state utility in patients with age related macular degeneration: the association of contrast sensitivity and visual acuity.

BACKGROUND: There has been increasing interest in the use of measures of health related quality of life (HRQoL) and health state utility values in Age Related Macular Degeneration (ARMD). Visual acuity has been found to be an important determinant of such measures in previous studies. More recently, another measure of visual impairment, contrast sensitivity has received considerable attention. We designed a study to examine whether the contribution of contrast sensitivity in explaining HRQoL and health utilities over and above that of visual acuity. METHODS: 209 patients with unilateral or bilateral ARMD were recruited into a cross-sectional study of patients from a large teaching hospital. Patients underwent visual tests (near and distant visual acuity, contrast sensitivity) and completed a vision function questionnaire, the VF-14, HUI3, and time trade-off. RESULTS: Using multivariate regression analysis, the study revealed that contrast sensitivity remained a statistically significant predictor of all outcome measures even when visual acuity was included. This result was supported by the correlation coefficients between measures. CONCLUSIONS: The measurement of contrast sensitivity appears to be better related to a person's HRQoL and health utility. Future studies should consider incorporating contrast sensitivity in addition to visual acuity. Studies, in particular economic evaluations, may underestimate the effect of treatment unless contrast sensitivity is considered.

Adult↗
PubMed1983

Contrast sensitivity throughout adulthood.

Previous studies of spatial contrast sensitivity in adulthood have produced conflicting results. To clarify the situation, we measured contrast sensitivity functions on a large sample of adults (n = 91), ranging in age from 19 to 87. All observers were free from significant ocular pathology and were individually refracted for the test distance. Sensitivity for stationary gratings of low spatial frequency remained the same throughout adulthood. At higher spatial frequencies, sensitivity decreased with age beginning around 40 to 50 years. When a low spatial frequency grating was drifted, young adults' sensitivity improved by a factor of 4-5 over sensitivity to a static grating; this motion enhancement was markedly diminished in adults over 60 years, implying an impairment of temporal processing in the elderly. Reduced retinal illuminance characteristic of the aged eye could account for a large part of older adults' deficit in spatial vision, but appeared to play little role in their deficit in temporal vision.

Adult↗
PubMed1974

Behavioural contrast sensitivity of the cat in various visual meridians.

1. The contrast sensitivity of the cat as a function of the spatial frequency of the visual stimulus was determined by using behavioural techniques.2. No statistically significant difference was found for the contrast sensitivity thresholds at various orientations of the stimulus.3. A comparison of the contrast sensitivity curve of the cat with that of the human shows that the two species have rather different characteristics of visual spatial resolution.

Animals↗
PubMed1992

Nonselective loss of contrast sensitivity in visual system testing in early type I diabetes.

OBJECTIVE: Psychophysical methods in patients with diabetes mellitus reveal deficits of central or foveal vision. Our aim was to evaluate the contrast-sensitivity thresholds in 24 insulin-dependent (type I) diabetic patients with a short disease duration and without retinopathy, taking into account metabolic control. RESEARCH DESIGN AND METHODS: The control group consisted of age-matched nondiabetic subjects. None had visual or systemic symptoms. Contrast sensitivity measured at eight different spatial frequencies to sinusoidal bar patterns of 0.6-12.2 cycles/deg can detect functional defects in the spatially sensitive retinal ganglion cells or in higher visual pathways. We performed two different temporal types of contrast-sensitivity testing, dynamic (8 Hz) and static (0 Hz). RESULTS: Significant losses with dynamic contrast-sensitivity test at all but the highest spatial frequencies (i.e., 12.2 cycles/deg) were shown, whereas there was significant attenuation of contrast sensitivity at five spatial frequencies (1.0, 1.4, 2.2, 7.1, and 9.6 cycles/deg) in the static mode. Grating losses (less than 2SD of control means) of contrast sensitivity were found in 33.3% (dynamic) and in 72.9% (static) of eyes of diabetic patients. HbA1c values were positively correlated at variable spatial frequencies (1.0, 1.4, and 2.2 cycles/deg for dynamic test and 0.6, 1.0, 1.4, 2.2, 4.8, and 7.1 cycles/deg for static test). CONCLUSIONS: Our results suggest an early, generally nonselective neuronal damage of visual pathways that occurs before the onset of clinically detectable retinopathy. The visual deficit may be related directly to the effects of diabetes; repetitive minor hypoglycemic insults may contribute more than a marked hyperglycemic condition to the mechanisms underlying physiological changes along the optic nerve.

Adult↗