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PubMed1989

[Contrast sensitivity in amblyopia].

The contrast sensitivity function for sinusoid gratings of various spatial frequencies was determined for both eyes of 21 cases with unilateral amblyopia. The CSF of all amblyopic eyes except one was reduced in comparison with the non-amblyopic eye of the same person. The CS curve was depressed, especially with the middle and high spatial frequencies. The cut-off high frequency shifted toward to the left, as was the peak sensitivity. The changes in CSF with respect to different degrees of amblyopia, and the possible errors that could be made during the examination were also discussed.

Adolescent↗
PubMed1994

Modelling contrast sensitivity as a function of retinal illuminance and grating area.

We extended the contrast detection model of human vision [Rovamo, Luntinen & Näsänen (1993b) Vision Research, 33, 2773-2788] to low light levels by taking into account the effect of light-dependent quantal noise. The extended model comprises (i) low-pass filtering due to the optical modulation transfer function of the eye, (ii) addition of light-dependent noise at the event of quantal absorption, (iii) high-pass filtering of neural origin (lateral inhibition), (iv) addition of internal neural noise, and (v) detection by a local matched filter whose efficiency decreases with increasing grating area. To test the model we measured foveal contrast sensitivity as a function of retinal illuminance and grating area at spatial frequencies of 0.125-32 c/deg. In agreement with the model, monocular contrast sensitivity at all grating areas increased in proportion to I when retinal illuminance (I) was smaller than critical illuminance. Thereafter the increase saturated and contrast sensitivity became independent of retinal illuminance. Similarly, at all levels of retinal illuminance contrast sensitivity increased in proportion to A when grating area (A) was smaller than critical area. Thereafter the increase saturated and contrast sensitivity became independent of area. Critical level of retinal illuminance increased in proportion to the spatial frequency squared. Critical area marking the saturation of spatial integration was constant at low spatial frequencies but decreased in inverse proportion to spatial frequency squared at medium and high spatial frequencies. The maximum contrast sensitivity obtainable by spatial integration in bright light increased at low spatial frequencies in proportion to spatial frequency, was constant at medium spatial frequencies, and decreased in inverse proportion to spatial frequency cubed at high spatial frequencies. The increase was due to the neural modulation transfer function of the visual pathways whereas the decrease was due to the optical modulation transfer function of the eye. The model explained 91-99% of the total variance of our contrast sensitivity data at various spatial frequencies.

Adult↗
PubMed2005

Attention enhances contrast sensitivity at cued and impairs it at uncued locations.

Transient covert attention increases contrast sensitivity at the target location with an informative spatial cue. Here we explored whether an uninformative spatial cue (50% valid with two possible locations) also increases contrast sensitivity and whether contrast sensitivity is altered at the uncued location as compared to the neutral condition. For all four observers, transient covert attention had both a benefit and a cost: it enhanced contrast sensitivity at the cued location and impaired contrast sensitivity at the uncued location at both parafoveal and peripheral positions. These results are consistent with the idea of limited resources, and indicate that transient attention helps control the expenditure of cortical computation.

Attention↗
PubMed1999

Role of clearance and treatment zones in contrast sensitivity: significance in refractive surgery.

PURPOSE: To evaluate the relationship between contrast sensitivity, surgical treatment zone, and clearance (ablation or clear zone-pupil diameter) in photorefractive keratectomy (PRK) and radial keratotomy (RK). SETTING: Saint Louis University Eye Institute, St. Louis, Missouri, and Hunkeler Eye Center, Kansas City, Missouri, USA. METHODS: Thirteen patients had PRK and 20, RK. Contrast sensitivity was measured with the Stereo Optical F.A.C.T. (F.A.C.T.) and VectorVision CSV-1000 (VV) charts. Pupils were measured with the Rosenbaum card. RESULTS: In the PRK group, VV contrast sensitivity at 6 and 12 cycles per degree (cpd) correlated with the ablation zone (r2 = 0.18 and 0.22, respectively), while visual acuity and F.A.C.T. contrast sensitivity did not correlate. In the RK group, both VV and F.A.C.T. contrast sensitivity at 6 cpd correlated with clearance (r2 = 0.29 and 0.12, respectively). Pupils were larger with the VV test than with the F.A.C.T. chart because ambient chart luminance was less in the former. CONCLUSION: Contrast sensitivity is likely a more sensitive indicator of visual function than acuity in refractive surgery. The VV system unmasks aberrations from the transition zone of ablated and unablated cornea in PRK. Larger samples are needed to determine the critical ablation clearance of the pupil to avoid loss of visual function.

Adult↗
PubMed2001

Increased binocular enhancement of contrast sensitivity and reduced stereoacuity in Duane syndrome.

PURPOSE: To compare the binocular enhancement of contrast sensitivity and stereoacuity in patients with Duane syndrome and normal subjects. METHODS: Monocular and binocular contrast sensitivity functions were determined using a two-alternative, forced-choice method in 14 patients with Duane syndrome and 14 normal subjects. Monocular and binocular log minimum angle of resolution (logMAR) acuities were measured, and stereoacuity was determined using the Titmus and TNO stereotests. RESULTS: In the patients with Duane syndrome, the binocular enhancement of contrast sensitivity was increased across all spatial frequencies, although stereoacuity was reduced compared to that of the normal subjects. The increased enhancement was caused by a reduction in monocular contrast sensitivity rather than an increase in binocular contrast sensitivity. The patients with Duane syndrome also showed a generalized reduction of contrast sensitivity at high spatial frequencies. CONCLUSIONS: It is suggested that the combination of reduced stereoacuity and increased binocular enhancement of contrast sensitivity seen in Duane syndrome can be explained by a partial loss of binocular cortical cells, caused by intermittent misalignment of the eyes during early visual development.

Adolescent↗
PubMed2001

[Effect of cataract surgery on contrast sensitivity].

The authors examined in a group of patients with cataract the visual acuity on Snellen's optotypes and contrast sensitivity using Pelli-Robson's test before cataract surgery and after cataract extraction and implantation of an intraocular lens. A VF-7 questionnaire was used for subjective evaluation of the result of surgery. The values of contrast sensitivity of the pseudophakic eyes were compared with the contrast sensitivity of eyes of a age-matched control group with a natural lens. After cataract surgery and lens implantation highly significant improvement of visual acuity of the operated eye was recorded. There was also significant improvement of binocular contrast sensitivity in the study group. The authors did not detect a significant difference of the contrast sensitivity of eyes with a PMMA lens and eyes with a silicone lens. There was no significant difference in the contrast sensitivity of pseudophakic eyes and phakic eyes of the control group. The CF-7 questionnaire revealed that cataract surgery led to significant improvement of the investigated visual activities, as apparent from the subjective evaluation by the patients. However, no significant correlation was found between objective (contrast sensitivity) and subjective (VF-7 questionnaire) evaluation of cataract surgery. Only one question in the questionnaire correlated significantly with contrast sensitivity. The authors found a significant reduction of contrast sensitivity caused by an altered transparency of the lens. The decline of contrast sensitivity in eyes with cataract and relatively good vision on Snellen's optotypes is the cause of some subjective complaints of the patients and may be an important factor in indication of cataract surgery of eyes with a relatively good visual acuity.

Aged↗
PubMed1994

Contrast sensitivity in diabetic retinopathy after panretinal photocoagulation.

Reports of changes in contrast sensitivity in proliferative diabetic retinopathy (PDR) patients after panretinal photocoagulation (PRP) have considered only relatively short-term results, and these have been conflicting. We evaluated contrast sensitivity changes in 30 eyes of 29 PDR patients after PRP. The patients were divided into two groups. One, group A, received PRP at one sitting, and the other, group B, at two sittings. Before and at regular intervals after PRP, all of the patients underwent a battery of macular function tests for best-corrected visual acuity, color vision, contrast sensitivity, and photostress. Contrast sensitivity was significantly affected (P < .001) in both groups immediately after PRP, but stabilized to prelaser levels by the end of 3 months. Color-vision-error scores also were significantly higher (P < .001) immediately after PRP. Best-corrected Snellen visual acuity, however, remained stable at prelaser levels. Contrast sensitivity appears to provide a more sensitive measurement of visual acuity than the Snellen chart for monitoring foveal integrity in patients undergoing PRP.

Adult↗
PubMed1997

Near vision contrast sensitivity after photorefractive keratectomy.

BACKGROUND: To evaluate near vision contrast sensitivity as a measure of visual performance after photorefractive keratectomy (PRK). SETTING: LSU Eye Center, New Orleans, Louisiana. METHODS: Using Holladay Contrast Acuity Test cards, near (reading) vision for five levels of contrast sensitivity was evaluated in a cross section of 53 eyes of 31 patients 25 to 732 days after PRK. Twenty-four normal eyes of 22 myopic patients served as controls. RESULTS: Near contrast sensitivity decreased at all tested contrast levels for approximately 7 months after PRK and then returned to baseline. This phenomenon paralleled the fluctuation in best corrected distance Snellen acuity. CONCLUSIONS: These preliminary results indicate that Snellen visual acuity and near contrast sensitivity returned to baseline within 1 year after PRK.

Adult↗
PubMed1998

Contrast sensitivity and glare disability with diffractive and refractive multifocal intraocular lenses.

PURPOSE: To compare contrast sensitivity and glare disability provided by diffractive and refractive multifocal intraocular lenses (IOLs). SETTING: University Eye Clinic Vienna, Austria. METHOD: This study evaluated the contrast sensitivity and glare disability in 29 eyes with a diffractive multifocal IOL (3M815LE) and 12 with a three-piece, five-zone refractive multifocal IOL (AMO Array SSM 26 NB). The Brightness Acuity Tester (Mentor, Inc.) was used with stationary sinusoidal gratings at spatial frequencies of 0.5, 1, 3, 6, 11.4, and 22.8 cycles per degree (cpd) generated on a television monitor (Nicolet CS 2000). RESULTS: The contrast sensitivity functions of both multifocal IOL groups were within the reference range and were identical at 0.5, 1, and 22.8 cpd spatial frequencies. At 3, 6, and 11.4 cpd, the contrast sensitivity function in the diffractive IOL group was 6, 9, and 10% lower than in the refractive IOL group, and the difference between groups was statistically significant at 6 cpd. When glare was present, contrast sensitivity in the diffractive IOL group was generally in the lower limit of the reference range and remained below at 3 and 6 cpd. Contrast sensitivity in the refractive IOL group remained below the reference range at 3 cpd. At 0.5 and 1 cpd, there were no differences between the groups. At the middle and high spatial frequencies (3, 6, 11.4, 22.8 cpd), contrast sensitivity in the diffractive group was 8, 16, 11, and 12% lower than in the refractive group. At 6 cpd, the between-group difference was statistically significant. CONCLUSION: Diffractive multifocal IOLs provided decreased contrast sensitivity and greater glare disability than refractive multifocal IOLs.

Adult↗
PubMed2004

Mesopic contrast sensitivity in the presence or absence of glare in a large driver population.

BACKGROUND: To evaluate mesopic contrast sensitivity in conditions of glare and no glare in a vehicle driver population, and to explore the effects of age, habitual spectacle correction, photopic visual acuity and driving exposure. METHODS: A cross-sectional study was performed on 297 drivers stratified by age into six groups. The mesopic contrast sensitivity was measured in the absence or presence of glare using the Mesotest II (Oculus, Germany) in each subject both with habitual and best spectacle correction. A questionnaire on the subject's driving habits was completed. RESULTS: There were no significant differences between contrast sensitivity measured with habitual or best spectacle correction. In conditions of no glare, the mesopic contrast sensitivity gradually got worse from 51 to 60 years onwards, and from 41 to 50 years onwards in the presence of glare. In both conditions, the total decrease in contrast sensitivity was 0.3 log units. The with-glare and without-glare mesopic contrast sensitivity improved as photopic visual acuity increased. Forty-five per cent of drivers who reported difficulties in driving at night were unable to perform any of the tests with glare, compared to 20% without glare. However, the effect of driving habits on contrast sensitivity was only significant in the oldest age group. CONCLUSIONS: The mesopic contrast sensitivity and glare sensitivity seem to be stable until the age of 50 years, from which point they start to decline at a rate of 0.1 log contrast sensitivity loss per decade. Drivers with poor visual acuity and/or older drivers who avoided night driving presented worse mesopic contrast sensitivity and greater glare sensitivity.

Adult↗
PubMed1999

Effects of defocus and pupil size on human contrast sensitivity.

Defocus lowers the contrast sensitivity function (CSF), producing a complex function with local dips and peaks. Previously, we were able to predict the shape of the CSF with large pupils from measured transverse aberrations with hypermetropic defocus but not with myopic defocus (Atchison et al., 1998c, J. Opt. Soc. Am. A. 15, 2536). As there is no reason that myopic defocus should be more difficult to predict than hypermetropic defocus, we modified the procedure to try to improve CSF predictions with myopic defocus. Also, we extended the study to consider a range of pupil sizes. CSFs were measured for three subjects at three defocus levels (in-focus, -2D and +2D) and three pupil sizes (2 mm, 4 mm and 6 mm). Using a diffraction optics model, transverse aberration measures and in-focus CSF measures, we predicted the defocused CSFs. The predicted defocused CSFs were lower than the in-focus CSF as expected, and had complex shapes that varied with defocus and pupil size and between subjects. While a few predictions were poor, generally, the overall magnitude and shape of the defocused CSFs were well predicted and similarly so for myopic and hypermetropic defocus. Some further improvements in technique are indicated.

Accommodation, Ocular↗
PubMed1981

Improved contrast sensitivity with antireflective coated lenses in the presence of glare.

Contrast sensitivity was measured to quantify the glare-reducing effects of antireflective coatings of magnesium fluoride on spectacle lenses. Experiments were conducted on four subjects, who judged contrast thresholds while wearing corrective spectacles with noncoated and then coated lenses in both the absence and the presence of a source of glare (back-scattered reflection from the posterior surface of their lenses). Glare substantially reduced contrast sensitivity at all spatial frequencies; although the reduction was greater at higher spatial frequencies ther was no shift in peak contrast sensitivity. The coated lenses enhanced contrast sensitivity in the presence of glare between 1.5 and 5 times compared with the noncoated lenses. In the absence of glare, contrast sensitivity was greater with coated lenses than with noncoated lenses.

Adult↗
PubMed1988

Aging, senile miosis and spatial contrast sensitivity at low luminance.

The purpose of this study was to determine how aging affects spatial contrast sensitivity at low light levels and to examine whether senile miosis, which reduces retinal illuminance in the aged eye, underlies any observed sensitivity loss. Contrast thresholds for targets having a range of spatial frequencies were measured in young (n = 13, M age = 24) and older (n = 11, M age = 73) adults who were free from identifiable ocular pathology. Measurements were carried out at three luminance levels spanning a three log unit range. Results indicated that older adults' loss in contrast sensitivity not only increased with increasing spatial frequency, but also became more pronounced with decreases in luminance level. Additional threshold measurements where pupil diameter was varied indicated that senile miosis was not responsible for older adults' loss in spatial vision at any level tested. Rather, older adults' miotic pupil tended to have a positive effect on their spatial vision in that it slightly improved their contrast sensitivity.

Adult↗
PubMed2005

Blue-light filtering intraocular lens in patients with diabetes: contrast sensitivity and chromatic discrimination.

PURPOSE: To evaluate potential changes in contrast sensitivity and color discrimination in diabetic patients who had cataract surgery and implantation of the blue-light filtering AcrySof Natural (SN60AT) intraocular lens (IOL) compared with an ultraviolet-only filtering (AcrySof SA60AT) IOL. SETTING: Refractive Surgery Unit, Hospital NISA Valencia al Mar, Valencia, Spain. METHODS: Forty-four eyes of 22 diabetic patients were enrolled in a blue-light filtering fellow-eye control study. Patients received yellow-tinted IOLs (AcrySof Natural) in 1 eye and non-yellow-tinted IOLs (AcrySof SA60AT) in the fellow eye. Three months after surgery, monocular contrast sensitivity function was measured with the CSV 1000-E contrast sensitivity chart at distance and color discrimination was tested with the Farnsworth-Munsell 100-hue test. RESULTS: Eyes implanted with the blue-light filtering IOLs showed better contrast sensitivity values than fellow eyes implanted with non-yellow-tinted IOLs (P<.05). The blue-light filtering IOL did not modify chromatic discrimination compared with the non-yellow-tinted IOL (P = .62). In the blue-yellow axis discrimination study, the eyes implanted with the AcrySof Natural IOL had statistically significant better color vision (P = .008). CONCLUSIONS: In diabetic patients, the AcrySof Natural IOL provides better contrast sensitivity than the AcrySof SA60AT. The blue-light filter of the AcrySof Natural IOL did not cause chromatic discrimination defects based on total error scores and improved color vision in the blue-yellow chromatic axis in diabetic patients.

Aged↗
PubMed2005

Comparison of contrast sensitivity and color discrimination after clear and yellow intraocular lens implantation.

PURPOSE: To compare contrast sensitivity and color vision in patients in whom blue-light filtering and non-yellow-tinted intraocular lenses (IOLs) were implanted. SETTING: Refractive Surgery Unit, Hospital NISA Valencia al Mar, Valencia, Spain. METHODS: Forty eyes of 20 patients were enrolled in a blue-light filtering fellow-eye control study; patients were implanted with a yellow-tinted IOL (AcrySof Natural, Alcon) in 1 eye and a non-yellow-tinted IOL (AcrySof SA60AT, Alcon) in the fellow eye after cataract surgery. Three months postoperatively, monocular contrast sensitivity function was measured with the CSV 1000-E contrast sensitivity chart at distance and the color discrimination with the Farnsworth-Munsell 100 Hue test. RESULTS: Eyes implanted with blue-light filtering IOLs showed similar contrast sensitivity to that in fellow eyes implanted with non-yellow-tinted IOLs (P>.1). Both types of IOLs showed normal contrast sensitivity values (normalized log-contrast sensitivity about 1.0). There were no statistically significant differences in chromatic discrimination between the 2 types of IOLs (P = .56). CONCLUSION: The use of blue-light filtering IOLs is more advisable because they are capable of protecting the retina against ultraviolet light without disturbance of contrast sensitivity and chromatic vision, which produces subjective impairment in visual function.

Aged↗
PubMed1988

Short-term influence of alcohol on spatial brightness contrast sensitivity.

The present crossover, controlled study demonstrates that alcohol at a blood concentration of approximately 0.08% reduces the contrast sensitivity (p less than 0.001). The mean contrast sensitivity was 15.03 dB in the control measurements and 14.39 dB in the measurements with alcohol. Brightness contrast sensitivity was measured with white, green, red and blue light, in this sequence. Therefore, the test design may present time effects as well as 'color effects'. The mean decrease in contrast sensitivity was with white light -1.26 dB, with green light -0.88 dB and with red light -0.57 dB. Contrast sensitivity tested with blue light showed even a slight increase with alcohol (+0.12 dB). The time interval between alcohol consumption and the test was important (p less than 0.001). The mean decrease in contrast sensitivity with alcohol in subjects with a short interval of 40 min was less reduced (-0.3 dB) than in subjects with a long interval of 60 min (-0.98 dB). In summary, at moderate doses of alcohol, contrast sensitivity is only moderately decreased and this decrease depends on the time between alcohol consumption and the test.

Adolescent↗
PubMed1992

Clinical contrast sensitivity chart evaluation.

Three different types of contrast sensitivity chart were used on normal patients by six optometrists in clinical practice. The charts were the Vistech, the Pelli-Robson and the Cambridge low-contrast gratings test. We examine the data in terms of the differences between optometrists and the variation of contrast sensitivity with the age of the patient. There was a highly significant difference between the scores from different optometrists for all three charts. We attribute this to variability in measurement technique. There was also a highly significant effect of age for all three charts, with older observers tending to exhibit lower contrast sensitivity. On the Vistech chart, this sensitivity deficit was most pronounced at higher spatial frequencies. The level of redundant information in the tests is discussed.

Adolescent↗
PubMed2001

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

PURPOSE: To investigate the relationship between large-letter contrast sensitivity, high-contrast visual acuity, and visual field defects in patients with glaucoma. METHODS: Patients with a diagnosis of glaucoma, glaucoma suspect, or ocular hypertension whose visual acuity was 20/40 (logMAR = 0.3) on better were included in the study. Visual acuity was measured using the Lighthouse visual acuity charts. Contrast sensitivity was measured using the Pell-Robson (PR) chart. The mean depression (MD) score from the most recent Humphrey visual field was used to quantify the visual field defect. RESULTS: A total of 120 eyes were studied. The PR contrast sensitivity score correlated more strongly with the MD of the visual field (r = .589, P < .001) than did the logMAR visual acuity (r = .193, P = .035). When just the eyes with open-angle glaucoma were considered (N = 54), the correlation was even greater for the PR score (r = .638). In ocular hypertensive eyes (N = 25), the correlations to PR and logMAR were not that different (r = .394 for PR, r = .303 for logMAR). Pseudophakic eyes did not show as strong a correlation (r = .335) as did phakic eyes (r = .591). CONCLUSION: For glaucomatous eyes with visual acuity of 20/40 or better, a decrease in the contrast sensitivity correlates with increased visual field loss. We speculate that this decrease in contrast sensitivity in glaucoma patients may account for their complaints of poor vision despite normal or near normal visual acuity.

Contrast Sensitivity↗