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PubMed1983

Effect of artificial central scotoma on the spatial contrast sensitivity of normal subjects.

Spatial contrast sensitivity was measured in normal subjects with and without a retinally stabilized artificial scotoma (either circular or rectangular), which precluded foveal vision. Our results indicate that the type of contrast sensitivity loss obtained (predominantly high frequency or overall) depended on temporal factors associated with grating presentation. A predominantly high frequency loss was obtained when grating contrast was turned on and off gradually. An additional low frequency difference was obtained when grating contrast was turned on and off abruptly.

Adult↗
PubMed2004

Contrast sensitivity deficits in inferred magnocellular and parvocellular pathways in retinitis pigmentosa.

PURPOSE: To define the contrast sensitivity deficits of patients with retinitis pigmentosa (RP) under testing conditions designed to emphasize threshold mediation by either the magnocellular (MC) or parvocellular (PC) pathway. METHOD: Contrast sensitivity was measured with spatially localized, narrow-band test patterns at peak spatial frequencies ranging from 0.25 to 8 cycles per degree (cpd), using a steady-pedestal paradigm (brief presentation of the test stimulus against a continuously presented luminance pedestal) and a pulsed-pedestal paradigm (simultaneous brief presentation of the test stimulus and luminance pedestal) to favor the MC and PC pathways, respectively. The contrast sensitivity functions of 12 patients with RP who had visual acuities ranging between 20/12.5 and 20/40 were compared to those of 10 visually normal, age-equivalent control observers. RESULTS: Five of the patients with RP who had Snellen visual acuities better than 20/25 had contrast sensitivity functions that were within the normal limits at all spatial frequencies for both testing paradigms. The other seven patients with RP had reduced contrast sensitivities for both paradigms, with the greatest reduction in sensitivity occurring at the highest spatial frequency. Their contrast sensitivity deficits were equivalent for the steady- and pulsed-pedestal paradigms. CONCLUSIONS: As observed in previous studies, the degree of contrast sensitivity loss shown by the patients with RP was greatest at the highest stimulus spatial frequency. However, in comparison to prior studies of contrast discrimination in patients with RP, there was no evidence of a preferential contrast sensitivity loss within the MC pathway. This apparent discrepancy is attributed to differences in the test targets and psychophysical judgments that were used in the studies, which emphasizes the importance of task characteristics in evaluating relative deficits within the MC and PC processing streams in visual disorders.

Adult↗
PubMed1984

Contrast sensitivity. The visual rehabilitation of the patient with macular degeneration.

Contrast sensitivity functions (CSFs) were determined on a large group of patients with macular degeneration to better assess qualitative aspects of their residual vision. Contrast sensitivity was also determined through the telescopic low-vision aids of selected patients. In general, the patients have a substantial loss of contrast sensitivity for all spatial frequencies. The preferred eye of these patients appeared to be related to the peak of the CSF more so than to the Snellen visual or resolution acuity. Through the low-vision aid, not only was there the predictable increase in resolution acuity but also a notable increase in peak contrast sensitivity. These findings indicate that contrast sensitivity testing provides useful information that should be considered in the visual rehabilitation of the patient with macular degeneration.

Aged↗
PubMed1997

Eye movement-based measures of development of spatial contrast sensitivity in infants.

This study presents spatial contrast sensitivity functions from 66 infants ranging in age from 12 to 146 days. Functions were derived using a behavioral method based on eye movements; in this method, the subject viewed drifting sinusoidal gratings while an experimenter, who did not know the direction of stimulus drift, voted on that direction based only on the record of the subject's eye movements. Results show that there is a marked increase in contrast sensitivity across age, as well as a modest shift of the peak of the function and of the acuity limit to higher spatial frequencies. However, when normalized with respect to peak frequency and peak sensitivity, the functions at all ages have the same general shape and can be fit with a standard template curve used to describe contrast sensitivity in the adult visual system; that is, even the youngest infants clearly show a drop in sensitivity at frequencies below the peaks of their functions.

Adult↗
PubMed1983

Contrast sensitivity of hemodialysis patients.

The contrast sensitivity of patients undergoing hemodialysis therapy for chronic renal failure was measured and compared to that of a control group. Both contrast sensitivity and visual acuity of the patients were reduced. Ocular and fundoscopic exams revealed differences between the patients and controls, but these differences could not fully account for the visual deficits. The visual deficits could be expected to cause reduced visibility under everyday conditions for the patients.

Adult↗
PubMed1980

Contrast sensitivity in children and adults.

Contrast sensitivity functions to vertical sinusoidal gratings have been measured in 135 subjects ranging from 3 to 29 years of age. The reported contrast sensitivities for all spatial frequencies increased steadily with age, reaching adult levels during adolescence. The usefulness of these functions as a clinical test is discussed.

Adolescent↗
PubMed1991

Spatial contrast sensitivity of goldfish: mean luminance, temporal frequency and a new psychophysical technique.

Behavioral contrast sensitivity in goldfish was examined at various mean luminances and stimulus drift rates. Goldfish were classically conditioned to suppress respiration upon presentation of a drifting sinusoidal grating. Contrast threshold at each spatial frequency was determined by means of a new two-alternative forced-choice procedure in which the observer's decision about the presence of the stimulus was based on the animal's respiration pattern. The results show that: (1) as mean luminance decreases, contrast sensitivity to high spatial frequencies decreases and peak sensitivity shifts to lower spatial frequencies; (2) as drift rate increases, contrast sensitivity to low spatial frequencies increases, but sensitivity to high spatial frequencies is relatively unaffected by stimulus drift rate. Both the mean luminance and temporal frequency of the stimulus clearly influence the behavioral contrast sensitivity of the goldfish in ways that would be predicted from behavioral results from other species. We conclude that the mechanisms that mediate contrast sensitivity in goldfish are similar to those that mediate contrast sensitivity in other vertebrates.

Animals↗
PubMed1997

Development of spatial contrast sensitivity from infancy to adulthood: psychophysical data.

PURPOSE: This study examined changes in contrast sensitivity, the location of the peak of the contrast sensitivity function (CSF), and the shape of the function from infancy to adulthood. METHODS: Contrast thresholds were obtained using behavioral methods, preferential looking for infants, and operant techniques for older children and adults, with the same stimuli for all ages. RESULTS: Contrast sensitivity at the peak improved almost two log units from infancy to adulthood. Much of the shift in the peak to higher spatial frequencies occurred in infancy. Sensitivity was not yet at adult levels at 8 years of age. CONCLUSIONS: The reduction in contrast sensitivity at the lowest frequency between 2 and 4 months of age suggests an increase in lateral inhibition during early infancy. Contrast sensitivity at the peak increased by two log units from then until adulthood.

Adolescent↗
PubMed1994

A comparison of two contrast sensitivity tests and their usefulness as a screener for aircrew.

This study investigated the usefulness of two contrast sensitivity tests for aircrew selection. The first, carried out on a Nicolet CS 2000 Contrast Sensitivity System, used a two-interval forced choice methodology (2IFC) and an adaptive procedure. The second was the VISTECH VCTS 6500 Test System. The contrast sensitivity of 50 aircrew candidates and 23 subjects was measured. Two independent measures were taken on the 23 subjects to get an estimate of test-retest variability. Mean contrast sensitivity with the 2IFC methodology was significantly higher at 1.5, 3, and 6 cpd than with the VCTS 6500. The variance in the scores of the aircrew population on the VCTS 6500 was almost identical to the within-subject variance based on the test-retest data. Thus, any differences in contrast sensitivity across the aircrew population could not be picked up by the VCTS 6500. The variance in the scores of the aircrew candidates with the 2IFC method was larger than the within-subject variance, but the evidence suggested that most of this variation was due to factors other than differences in contrast sensitivity across the aircrew population. It was concluded that neither test was suitable for screening the contrast sensitivity of Canadian Forces aircrew candidates, but that both tests could be useful for testing more heterogeneous populations. Moreover, since the shape of the contrast sensitivity function varies across tests, absolute scores on different tests are not comparable.

Adolescent↗
PubMed1992

Contrast sensitivity measurements with the Echelon diffractive bifocal contact lens as compared to bifocal spectacles.

We examined the contrast sensitivity function of presbyopic subjects wearing the Hydron Echelon diffractive bifocal contact lens. Contrast sensitivity with the Echelon lens was compared to contrast sensitivity with bifocal spectacle correction. Each eye was tested for near and distance vision with the Echelon contact lens and with spectacle correction. Most subjects achieved a visual acuity of 20/20 with the Echelon lens; however, on average, contrast sensitivity was found to be significantly decreased with the contact lens as compared to spectacles for both distance and near vision. The largest decrease in contrast sensitivity was seen for mid-range spatial frequencies (4 to 16 cycles/degree). Although most subjects experienced a significant decrease in contrast sensitivity, two experienced only small decreases with the Echelon lens. Only one subject who met entry criteria reported that vision was as good with the Echelon lens as with spectacles. The decreased contrast sensitivity may result from contact lens decentration as well as inherent optical characteristics of the Echelon lens.

Adult↗
PubMed2003

The impact of acuity on performance of four clinical measures of contrast sensitivity in Alzheimer's disease.

Investigations of contrast sensitivity losses in Alzheimer's disease (AD) have yielded mixed findings, with some investigators reporting deficits and others not. Potential reasons for these discrepancies include differences between samples and assessments utilized and the failure of some investigators to account for acuity differences between groups. To investigate these issues, we administered four clinical contrast sensitivity assessments to the same group of AD patients and elderly control participants and examined the impact of acuity on performance for each assessment. Results revealed group differences across the spatial frequency range. Further, group acuity differences significantly affected performance on two of the four measures (the Regan and the Vistech but not on the Pelli-Robson or Freiburg assessments). Information regarding the availability of established age norms, test-retest reliability data, and other factors including the time, cost, and training needed to administer each measure is provided to aid clinicians and researchers in their search for an effective measure of contrast sensitivity.

Aged↗
PubMed1987

A quantitative investigation into the effects of pupil diameter and defocus on contrast sensitivity for an extended range of spatial frequencies in natural and homatropinized eyes.

Contrast sensitivity was measured in 12 subjects for different spatial frequencies of sinusoidal grating patterns, generated by oscilloscope, for pupil diameters 2-8 mm and for defocus of +1-4 D, following homatropine eyedrops. Changes in pupil diameter, without correction for the change in retinal illumination, had no significant effect on contrast sensitivity, except at 0.5 and 1 c deg-1 when a significant reduction occurred with the 2 mm pupil. Defocus caused a large reduction in contrast sensitivity at spatial frequencies higher than the peak of the contrast sensitivity function (3 c deg-1) and a smaller reduction below the peak. In both individual and group results, there was no significant effect of defocus in causing a disproportionately greater reduction in contrast sensitivity at higher spatial frequencies nor were the zero mimina predicted by optical theory observed. The results were confirmed in eight subjects viewing with the natural eye, though the reduction in contrast sensitivity caused by +1 D defocus was not significant: this was attributed to the relaxation of accommodation in response to defocus. To predict the performance of the visual system, multiple regression equations were derived to incorporate terms for pupil diameter, defocus and spatial frequency. These equations reflected the lack of effect of pupil diameter, while defocus caused a 51% loss in contrast sensitivity per dioptre at higher spatial frequencies (3-38 c deg-1) and a 19% reduction at low spatial frequencies.

Accommodation, Ocular↗
PubMed1998

[Contrast sensitivity in glaucoma and ocular hypertension].

It is known that contrast sensitivity declines with advancinG age and during different ophthalmological diseases. The authors examined 263 eyes of 141 patients with different types of glaucoma and 213 eyes of 107 patients with ocular hypertension. The patients were divided into two groups by age: A = under 60 years (mean 53.2 in glaucoma, 51.1 in OH) and B = 60 years and above (mean 67.5 in glaucoma and 65.6 in OH). For examination of contrast sensitivity the authors used a VCTS 6500 board from a 3 m distance, the visual field was examined by means of Goldman's kinetic perimeter or a static Optifield II perimeter and the discs of the optic nerve were examined biomicroscopically or a photograph of the disc was taken. Impaired contrast sensitivity was found in group A in 71.7% of glaucoma patients and in 61.6% in ocular hypertension. In group B in 81.7% glaucoma patients and in 75.1% of patients with ocular hypertension. The authors also proved an association between the decline of contrast sensitivity and impairment of the perimeter and enlargement of the glaucoma excavation of the optic disc. The authors recommend examination of the contrast sensitivity as a supplementary method for screening and observation of ocular hypertension and glaucoma.

Aged↗
PubMed1987

Contrast sensitivity decline with ageing: a neural or optical phenomenon?

Previous studies of contrast sensitivity changes with age have produced conflicting results. Most recent reports indicate that, with increasing age, contrast sensitivity at medium and high spatial frequencies decreases. Whether this is caused by reduced retinal illumination due to senile pupillary miosis and increased lens absorption, by the greater light scatter of the aged eye or by retinal and neural cell loss and degeneration is also in doubt. We measured the contrast sensitivity functions of 16 young (mean age 21.5 +/- 2.7 years) and 16 older (mean age 72 +/- 4.3 years) subjects with normal healthy eyes, using a modified Rodenstock retinometer and a monitor-based computer system. The former method bypasses the effects of the optical media to measure the contrast sensitivity function of the retinal and neural system alone, while the latter measures the contrast sensitivity function of the whole visual system, including media. The results show the older group to have significantly lower contrast sensitivity at medium (4 c deg-1, p less than 0.1) and high (10.6 c deg-1, p less than 0.001; 16.5 c deg-1, p less than 0.001) spatial frequencies. They also suggest that this is due primarily to retinal and neural changes with age, with optical factors having a slight effect at the highest spatial frequency only.

Adult↗
PubMed1979

The influence of the stimulus width on the contrast sensitivity function in amblyopia.

The contrast sensitivity function of both eyes of subjects with functional amblyopia has been measured. A clinically significant difference was found between the amblyopic and the normal eye. It appears that the functionally amblyopic eye takes more information from the peripheral parts of the stimulus than does the normal eye. The sensitivity of the normal eye increases linearly with increasing width of the stimulus to show a knee at a certain number of grating lines, whereafter the sensitivity remains constant. The sensitivity of the amblyopic eye initially rises much faster than that of the normal eye with increasing stimulus width. In the amblyopic eye, there is no definite linear relationship between width of stimulus and the contrast sensitivity and no definite knee in the curve at which maximum sensitivity is reached.

Amblyopia↗
PubMed1989

[Contrast sensitivity in glaucoma].

Author reports on results of the contrast sensitivity examinations using the Cambridge low-contrast lattice test supplied by Clement Clarke International LTD, in patients with open-angle glaucoma and ocular hypertension. In glaucoma patients there was observed statistically significant decrease of the contrast sensitivity. In patients with ocular hypertension decrease of the contrast sensitivity was in patients affected by corresponding changes of the visual field and of the optical disc. The main advantages of the Cambridge low-contrast lattice test were simplicity, rapidity and precision of its performance.

Adult↗
PubMed1972

Visual acuity and contrast sensitivity in patients with cerebral lesions.

Spatial contrast sensitivity as a function of spatial frequency was measured in patients with cerebral lesions. In most of these patients visual acuity, as measured by the Snellen chart, was 20/30 or better, yet marked departures from normal contrast sensitivity were found. The greatest loss in contrast sensitivity occurred at high frequencies, but in one patient the loss was greatest in the midfrequency range. This finding lends support to the channel hypothesis of spatial contrast discrimination.

Adult↗
PubMed2001

Normal values for the Pelli-Robson contrast sensitivity test.

PURPOSE: To define normal values for the Pelli-Robson contrast sensitivity test in different age groups. SETTING: University Eye Clinic of Kuopio, Kuopio, Finland. METHODS: Contrast sensitivity was measured with the Pelli-Robson contrast sensitivity test in 87 persons (60 women and 27 men) with a mean age of 34.5 years +/- 20.8 (SD) (range 6 to 75 years). Results were studied by age group (years): 6 to 9, 10 to 19, 20 to 29, 30 to 39, 40 to 49, 50 to 59, and 60 and older. Of 163 eyes, both were healthy in 76 persons and 1 was healthy in 11. Study participants consisted of members of the staff of the Kuopio University Hospital Eye Clinic, medical students at the Kuopio University, and patients of the Strabismus and General Ophthalmology Units of the Eye Clinic and their accompanying persons. Two test distances were used: 1 m and 3 m. Eyes were tested individually; thereafter, the test was done binocularly. RESULTS: There were significant differences in logarithmic contrast sensitivity values among the age groups except on the test of the left eye at 1 m. The P values for the right eye at 1 m and 3 m, left eye at 1 m and 3 m, and both eyes at 1 m and 3 m were 0.003, 0.002, 0.19, 0.043, 0.037, and 0.003, respectively. The mean test results in 1 eye varied from 1.68 in the 60 year and older group to 1.84 in the 20 to 29 and 30 to 39 year groups. Binocularly, the variation was from 1.73 in the 40 year group to 1.99 in the 30 year group. CONCLUSIONS: The Pelli-Robson contrast sensitivity test is a quick and reliable method in a clinical setting. Normal values of the test can be of help in evaluating cataract patients or patients having refractive surgery.

Adolescent↗