Contrast Sensitivity Measurements Research Articles

The SPARCS: a novel assessment of contrast sensitivity and its reliability in patients with corrected refractive error

PurposeTo explore the reliability of the Spaeth/Richman Contrast Sensitivity (SPARCS) test and to assess the contrast sensitivity (CS) distribution among subjects with various refractive errors.MethodsCross-sectional study. Ninety-three individuals (182 eyes)...

Repeatability of contrast sensitivity testing in patients with age-related macular degeneration, glaucoma, and cataract.

To analyze the intrasession and intersession repeatability of contrast sensitivity (CS) measurements in patients with glaucoma, cataract, or age-related macular degeneration (AMD) and healthy controls. CS measurements were performed using the OPTEC-Functional Vision Analyzer (FVA), which uses a standardized and closed (view-in) system. Measurements for patients with glaucoma, cataract, or AMD and healthy controls were repeated within 30 minutes (intrasession) and during two sessions (intersession), separated by one week to one month. Test-retest reliability and correlation were measured using the intraclass correlation coefficient (ICC) and coefficient of repeatability (COR). Ninety subjects (90 eyes) with visual acuity of 0.17 logMAR or higher in the cataract group or 0.00 logMAR in the other groups were included. During the first session, the ICC values were 0.87, 0.90, 0.76, and 0.69, and COR values were 0.24, 0.20, 0.38, and 0.25 for the control, glaucoma, cataract, and AMD groups, respectively. The reliability scores significantly improved during the second session, except in the glaucoma group. There was an acceptable floor effect and no ceiling effect at higher frequencies in the glaucoma and AMD groups. In subjects with good visual acuity, the FVA system is useful for evaluating CS and demonstrates good repeatability, as shown by ICC and COR. Because there is no ceiling effect, this system is beneficial for evaluation of early changes in CS, particularly in patients with glaucoma or AMD.

Visual resolution and contrast sensitivity in two benthic sharks.

Sharks have long been described as having 'poor' vision. They are cone monochromats and anatomical estimates suggest they have low spatial resolution. However, there are no direct behavioural measurements of spatial resolution or contrast sensitivity. This study estimates contrast sensitivity and spatial resolution of two species of benthic sharks, the Port Jackson shark, Heterodontus portusjacksoni, and the brown-banded bamboo shark, Chiloscyllium punctatum, by recording eye movements in response to optokinetic stimuli. Both species tracked moving low spatial frequency gratings with weak but consistent eye movements. Eye movements ceased at 0.38 cycles per degree, even for high contrasts, suggesting low spatial resolution. However, at lower spatial frequencies, eye movements were elicited by low contrast gratings, 1.3% and 2.9% contrast in H portusjacksoni and C. punctatum, respectively. Contrast sensitivity was higher than in other vertebrates with a similar spatial resolving power, which may reflect an adaptation to the relatively low contrast encountered in aquatic environments. Optokinetic gain was consistently low and neither species stabilised the gratings on their retina. To check whether restraining the animals affected their optokinetic responses, we also analysed eye movements in free-swimming C. punctatum We found no eye movements that could compensate for body rotations, suggesting that vision may pass through phases of stabilisation and blur during swimming. As C. punctatum is a sedentary benthic species, gaze stabilisation during swimming may not be essential. Our results suggest that vision in sharks is not 'poor' as previously suggested, but optimised for contrast detection rather than spatial resolution.

基于显示器特性的彩色对比敏感度测试

基于显示器特性的彩色对比敏感度测试

Contrast sensitivity in patients with monofocal and multifocal pseudophakia at spherical defocus of different degrees

In the present article, authors evaluate the influence of spherical defocus on contrast sensitivity level in patients with monofocal vs bifocal pseudophakia. The study included 27 patients (30 eyes) after cataract surgery, in whom contrast sensitivity in the setting of different illumination conditions at spherical defocus of different degree and sign was tested. To measure contrast sensitivity Optec® 6500 was used. Mann-Whitney U-test was used to compare results between groups. It was established that illumination level and defocus degree exert different influence on contrast sensitivity in patients with monofocal and bifocal pseudophakia.

Relationships Between Measures of the Ability to Perform Vision-Related Activities, Vision-Related Quality of Life, and Clinical Findings in Patients With Glaucoma.

To our knowledge, few studies have combined an objective measure of vision-related performance (VRP) and subjective measures of vision-related quality of life (VRQoL) with clinically related visual parameters, particularly in a large, prospective, cohort study setting. To examine the relationships between clinical visual assessments and both a VRP and 2 self-reported VRQoL measurements. Patients (N = 161) with moderate-stage glaucoma recruited from the Glaucoma Service at Wills Eye Hospital, Philadelphia, Pennsylvania, were enrolled from May 2012 to May 2014 in an ongoing prospective, 4-year longitudinal observational study. This report includes cross-sectional results from the baseline visit. Patients received a complete ocular examination, automated visual field (VF) test and Cirrus optical coherence tomographic scan. Contrast sensitivity was measured with the Pelli-Robson and the Spaeth-Richman Contrast Sensitivity (SPARCS) tests. Vision-related performance was assessed by the Compressed Assessment of Ability Related to Vision (CAARV) test. Vision-related QoL was assessed by the National Eye Institute Visual Function Questionnaire 25 (NEI-VFQ-25) and a modified Glaucoma Symptom Scale (MGSS). Correlations between clinical measures and CAARV, NEI-VFQ-25, and MGSS scores. A total of 161 patients were enrolled in the study. The strongest correlation was found between SPARCS score in the better eye and total CAARV score (r = 0.398; 95% CI, 0.235-0.537; P < .001). The CAARV score also correlated with the Pelli-Robson score (r = 0.353; 95% CI, 0.186-0.499; P = .001), VF mean deviation (r = 0.366; 95% CI, 0.200-0.510; P < .001), and VA (r = -0.326, 95% CI = -0.476 to -0.157; P = .003) in the better eye. There were more statistically significant correlations between contrast sensitivity tests and VF mean deviation with VRQoL measurements than with other clinical measures (visual acuity, intraocular pressure, Disc Damage Likelihood Scale, and mean retinal nerve fiber layer thickness). The MGSS scores were lower (worse) in women compared with men (P = .03 for binocular, P = .01 for better eye, and P = .05 for the worse eye). Structural measures (eg, Disc Damage Likelihood Scale, and retinal nerve fiber layer thickness) were generally not informative with respect to VRP or VRQoL. Contrast sensitivity tests and VF mean deviation were associated with both objective measures of the ability to act and subjective measurements of VRQoL. The strongest correlation was between SPARCS score (contrast sensitivity) in the better eye and total CAARV score. Therefore, measurement of contrast sensitivity should be considered when evaluating patients' VRQoL. The results of this study were limited by the patient population and apply only within the bounds of the tested cohort.

Subthreshold micropulse yellow laser treatment for nonresolving central serous chorioretinopathy.

PurposeTo report the efficacy and safety of micropulse 577 nm yellow laser in the treatment of nonresolving central serous chorioretinopathy (CSC) cases.Patients and methodsThe study included 15 eyes with nonresolving CSC lasting more than 3 months. All the patients were subjected to complete ophthalmic examination, in addition to contrast sensitivity measurement, fundus fluorescein angiography, and optical coherence tomography. All eyes were subjected to 577 nm subthreshold micropulse laser treatment, using the IQ 577 device, and followed up after 4 weeks, 2 months, 3 months, and 6 months. The outcome measures were change in best-corrected visual acuity, contrast sensitivity, subretinal fluid height, and change in macular thickness measured by optical coherence tomography.ResultsThe average age of the patients was 36.4 years; eleven were males and four were females. Average duration of the leakage was 4.6 months. The mean best-corrected visual acuity measured 6 months after laser treatment was 0.85±0.097, in comparison to 0.67±0.097 before laser treatment (statistically significant [SS], P<0.05). The mean central macular thickness before laser was 389.6±46.4 µm, in comparison to 263.6±24 µm after 6 months (SS, P<0.05). The mean post-laser log contrast sensitivity measured using the Pelli–Robson contrast sensitivity chart was 1.73±0.14, while the initial log contrast sensitivity was 1.48±0.28 (SS, P<0.05).ConclusionSubthreshold micropulse laser treatment is an effective and safe treatment option for patients with nonresolving CSC.

The Effects of tDCS Across the Spatial Frequencies and Orientations that Comprise the Contrast Sensitivity Function.

Transcranial Direct Current Stimulation (tDCS) has recently been employed in traditional psychophysical paradigms in an effort to measure direct manipulations on spatial frequency channel operations in the early visual system. However, the effects of tDCS on contrast sensitivity have only been measured at a single spatial frequency and orientation. Since contrast sensitivity is known to depend on spatial frequency and orientation, we ask how the effects of anodal and cathodal tDCS may vary according to these dimensions. We measured contrast sensitivity with sinusoidal gratings at four different spatial frequencies (0.5, 4, 8, and 12 cycles/°), two orientations (45° Oblique and Horizontal), and for two stimulus size conditions [fixed size (3°) and fixed period (1.5 cycles)]. Only contrast sensitivity measured with a 45° oblique grating with a spatial frequency of 8 cycles/° (period = 1.5 cycles) demonstrated clear polarity specific effects of tDCS, whereby cathodal tDCS increased and anodal tDCS decreased contrast sensitivity. Overall, effects of tDCS were largest for oblique stimuli presented at high spatial frequencies (i.e., 8 and 12 cycles/°), and were small or absent at lower spatial frequencies, other orientations and stimulus size. Thus, the impact of tDCS on contrast sensitivity, and therefore on spatial frequency channel operations, is opposite in direction to other behavioral effects of tDCS, and only measurable in stimuli that generally elicit lower contrast sensitivity (e.g., oblique gratings with period of 1.5 cycles at spatial frequencies above the peak of the contrast sensitivity function).

Retinal nerve fiber layer changes: A predictor of visual function recovery in pituitary adenomas

Abstract Objective To evaluate and correlate retinal nerve fiber layer changes on optical coherence tomography (OCT) with visual functions in pituitary adenomas in order to define OCT changes prognostic for visual recovery after neurosurgery. Methods Thirty-nine eyes of twenty patients undergoing surgical resection of pituitary adenomas were prospectively assessed by a detailed ophthalmological, radiological, and neurological examination including measurement of visual acuity, color vision, contrast sensitivity, stereoacuity, and visual field evaluation. Retinal nerve fiber layer thickness measurements were performed using OCT preoperatively and 6 weeks after surgery. Results After surgery, no significant change in visual acuity ( p = 0.067, Wilcoxon signed-rank test), stereoacuity ( p p = 0.52, paired t test) was noted. Significant improvement was observed in contrast sensitivity ( p = 0.001, paired t test), color vision ( p = 0.03, McNemar) and visual fields ( p p = 0.009, Fischer's exact test), contrast ( p p Conclusion In vivo retinal nerve fiber layer thickness measurement can accurately predict recovery of visual fields, contrast sensitivity, and color vision in pituitary adenomas after neurosurgery. Nasal quadrant retinal nerve fiber layer thickness is the most important prognostic factor in visual function recovery. Stereoacuity may be the earliest visual parameter to be affected.

Directional asymmetry in contrast sensitivity during smooth pursuit eye movement depends on spatial frequency

Abstract It is known that smooth pursuit eye movement (SPEM) modulates visual contrast sensitivity in an asymmetric manner. For instance, Schutz et al. (2007) reported that contrast sensitivity to a 1 c/deg grating is higher when it drifts in the same direction with the SPEM than in the opposite direction. They interpret this asymmetry in terms of the effect of spatial attention that moves together with, or even leads, the eye. The present study shows that this asymmetry is reversed at high spatial frequency bands. We measured contrast sensitivity for a spatially localized grating (Gabor patch) of 11 c/deg. The spatial window of the grating (s.d. of H0.8 x V0.4 deg) moved in the same velocity with SPEM (1.5 deg/sec), and thereby it was static on the retinal coordinate. The grating within spatial window drifted on the retina either in the same direction or in the opposite direction of SPEM. We found that for a range of retinal temporal frequencies tested (1.4-22.5 Hz), the observer's contrast sensitivity was substantially higher (0.1-0.25 log unit) when the grating drifted in the opposite direction of SPEM than in the same direction. This asymmetry was also observed for the cut-off temporal frequencies for a grating with a contrast of 0.5. For gratings of a low spatial frequency (0.5 c/deg), the cut off frequency was little, or not, higher for gratings in the same same direction than in the opposite direction of SPEM, consistent with the previous study. These results indicate that during smooth pursuit, the visual system becomes more sensitive to high-spatial frequency signals that moves slower than the eye than those that moves faster than the eye. The results cannot be well accounted for neither by spatial attention nor by sensitivity modulations of parvocellular and magnocellular channels. Meeting abstract presented at VSS 2015.

High order aberration and straylight evaluation after cataract surgery with implantation of an aspheric, aberration correcting monofocal intraocular lens.

To evaluate the quality of vision in respect to high order aberrations and straylight perception after implantation of an aspheric, aberration correcting, monofocal intraocular lens (IOL). Twenty-one patients (34 eyes) aged 50 to 83y underwent cataract surgery with implantation of an aspheric, aberration correcting IOL (Tecnis ZCB00, Abbott Medical Optics). Three months after surgery they were examined for uncorrected (UDVA) and corrected distance visual acuity (CDVA), contrast sensitivity (CS) under photopic and mesopic conditions with and without glare source, ocular high order aberrations (HOA, Zywave II) and retinal straylight (C-Quant). Postoperatively, patients achieved a postoperative CDVA of 0.0 logMAR or better in 97.1% of eyes. Mean values of high order abberations were +0.02±0.27 (primary coma components) and -0.04±0.16 (spherical aberration term). Straylight values of the C-Quant were 1.35±0.44 log which is within normal range of age matched phakic patients. The CS measurements under mesopic and photopic conditions in combination with and without glare did not show any statistical significance in the patient group observed (P≥0.28). The implantation of an aspherical aberration correcting monofocal IOL after cataract surgery resulted in very low residual higher order aberration (HOA) and normal straylight.

Impact of cataract surgery on vision-related life performances: the usefulness of Real-Life Vision Test for cataract surgery outcomes evaluation

Real-Life Vision Test (RLVT) is a newly developed performance-based measures of functional vision. This present study is designed to determine whether it could be a meaningful assessment for cataract surgery outcomes evaluation. Age-related cataract patients (56) who scheduled for bilateral cataract surgery and 44 age-matched controls were evaluated by four types of measurements: (1) demographic, medical, cognitive and depressive evaluation, and the reaction time testing; (2) clinical measures (visual acuity, contrast sensitivity, stereopsis, and color perception); (3) the 25-item National Eye Institute's Visual Functioning Questionnaire (NEI-VFQ); (4) the RLVT. Spearman's coefficients and multiple regression analysis were conducted to investigate the relationship among RLVT, clinical measures, and self-report assessment of visual function. The results of RLVT, clinical measures, and NEI-VFQ total scores were improved significantly after cataract surgery. There were no differences between control subjects and post-surgery patients with respect to NEI-VFQ-25 total scores, self-rating depression scale scores and three tasks of RLVT. Change of RLVT was significantly associated with the change of clinical measures in the cataract group. Multiple regression analysis demonstrated that change of distance, intermediate, and near visual acuity, and binocular contrast sensitivity were significant predictors of improvements of RLVT. Cataract surgery could improve real-world visual ability effectively for cataract patients. Our study highlights the potential usefulness of RLVT as an adjunct to the current outcomes evaluation system for cataract surgery. The use of RLVT combined with clinical and self-survey methods may be the comprehensive strategy to manifest the impact of cataract surgery on patients' overall vision-related quality of life.

Clinical Assessments as Predictors of Primary On-Road Outcomes in Parkinson's Disease.

Parkinson's disease (PD) is a neurodegenerative disorder that affects fitness to drive. Research that has examined clinical predictors of fitness to drive in PD, using the on-road assessment as the gold standard, has generally used a dichotomous pass/fail decision. However, on-road assessments may also result in one of two additional outcomes (pass with recommendations, or fail-remediable). Individuals within these subgroups may benefit from interventions to improve their fitness to drive abilities. This study investigated clinical predictors that could be indicative of the pass, pass with recommendations, or fail-remediable categories for drivers with PD (N = 99). Trails B, Left Finger to Nose Test, and contrast sensitivity measures were identified as significant predictors for the pass, and pass with recommendations subgroups. No significant predictors were identified for the fail-remediable subgroup. Results from this study provide a foundation for clinicians to identify drivers who can benefit from recommendations to preserve their driving abilities.

The Diabetes Visual Function Supplement Study (DiVFuSS)

BackgroundDiabetes is known to affect visual function before onset of retinopathy (diabetic retinopathy (DR)). Protection of visual function may signal disruption of mechanisms underlying DR.MethodsThis was a 6-month randomised, controlled...

Measurements of contrast sensitivity by an adaptive optics visual simulator

We developed an adaptive optics visual simulator (AOVS) to study the relationship between the contrast sensitivity and higher-order wavefront aberrations of human eyes. A desired synthetic aberration was virtually generated on a subject eye by the AOVS, and red laser light was used to measure the aberrations. The contrast sensitivity was measured in a psychophysical experiment using visual stimulus patterns provided by a large-contrast-range imaging system, which included two liquid crystal displays illuminated by red light emitting diodes from the backside. The diameter of the pupil was set to 4 mm by an artificial aperture, and the retinal illuminance of the stimulus image was controlled to 10 Td. Experiments conducted with four normal subjects revealed that their contrast sensitivity to a high-spatial-frequency vertical sinusoidal grating pattern was lower in the presence of a horizontal coma aberration than in the presence of a vertical coma or no aberrations (p < 0.02, Nagai method).

Comparison of visual status of Iranian military and commercial drivers.

Background:There is no legal requirement for Iranian military truck drivers to undergo regular visual checkups as compared to commercial truck drivers.Objectives:This study aimed to evaluate the impact of drivers’ visual checkups by comparing the visual function of Iranian military and commercial truck drivers.Patients and Methods:In this comparative cross-sectional study, two hundred military and 200 commercial truck drivers were recruited and their Visual Acuity (VA), Visual Field (VF), color vision and Contrast Sensitivity (CS) were assessed and compared using the Snellen chart, confrontation screening method, D15 test and Pelli-Robson letter chart, respectively. A questionnaire regarding driving exposure and history of motor-vehicle crashes (MVCs) was also filled by drivers. Results were analyzed using an independent samples t-test, one-way ANOVA (assessing difference in number of MVCs across different age groups), chi-square test and Pearson correlation at statistical significance level of P < 0.05.Results:Mean age was 41.6 ± 9.2 for the military truck drivers and 43.4 ± 10.9 for commercial truck drivers (P > 0.05). No significant difference between military and commercial drivers was found in terms of driving experience, number of MVCs, binocular VA, frequency of color vision defects and CS scores. In contrast, the last ocular examination was significantly earlier in military drivers than commercial drivers (P < 0.001). In addition, 4% of military drivers did not meet the national standards to drive as opposed to 2% of commercial drivers. There was a significant but weak correlation between binocular VA and age (r = 0.175, P < 0.001). However, CS showed a significantly moderate correlation with age (r = -0.488, P < 0.001).Conclusions:The absence of legal requirement for regular eye examination in military drivers caused the incompetent drivers to be missed in contrast to commercial drivers. The need for scientific revision of VA standard for Iranian drivers is also discussed. The CS measurement in visual checkups of older drivers deserves to be investigated more thoroughly.

Photopic and scotopic spatiotemporal tuning of adult zebrafish vision.

Sensitivity to spatial and temporal patterns is a fundamental aspect of vision. Herein, we investigated this sensitivity in adult zebrafish for a wide range of spatial (0.014 to 0.511 cycles/degree [c/d]) and temporal frequencies (0.025 to 6 cycles/s) to better understand their visual system. Measurements were performed at photopic (1.8 log cd m−2) and scotopic (−4.5 log cd m−2) light levels to assess the optokinetic response (OKR). The resulting spatiotemporal contrast sensitivity (CS) functions revealed that the OKR of zebrafish is tuned to spatial frequency and speed but not to temporal frequencies. Thereby, optimal test parameters for CS measurements were identified. At photopic light levels, a spatial frequency of 0.116 ± 0.01 c/d (mean ± SD) and a grating speed of 8.42 ± 2.15 degrees/second (d/s) was ideal; at scotopic light levels, these values were 0.110 ± 0.02 c/d and 5.45 ± 1.31 d/s, respectively. This study allows to better characterize zebrafish mutants with altered vision and to distinguish between defects of rod and cone photoreceptors as measurements were performed under different light conditions.

Are the visual transients from microsaccades helpful? Measuring the influences of small saccades on contrast sensitivity

Like all saccades, microsaccades cause both spatial and temporal changes in the input to the retina. In space, recent studies have shown that these small shifts precisely relocate a narrow (smaller than the foveola) high-acuity retinal locus on the stimulus. However, it has long been questioned whether the temporal modulations resulting from microsaccades are also beneficial for vision. To address this question, we combined spectral analysis of the visual input to the retina with measurements of contrast sensitivity in humans. Estimation of how different types of eye movements redistribute the power of an otherwise stationary stimulus shows that small saccades contribute more temporal power than ocular drift in the low-frequency range, suggesting a specific role for these movements in the encoding of low spatial frequencies. However, an influence on contrast sensitivity was only found for saccades with amplitudes larger than 30′. Contrast thresholds remained highly similar in the presence and absence of smaller saccades. Furthermore, saccades of all amplitudes, including microsaccades, were strongly suppressed during exposure to the stimulus. These findings do not support an important function of the visual transients caused by microsaccades.

Quantity and Quality of Vision Using Tinted Filters in Patients with Low Vision Due to Diabetic Retinopathy.

Purpose:To investigate the effect of tinted filters on visual acuity (VA), contrast sensitivity and patient satisfaction in diabetic retinopathy associated with low vision.Methods:In a prospective study, 51 patients with diabetic retinopathy and low vision were assessed. We chose a simple random sampling method and used the patient's files for data collection. LogMAR notations were applied for assessing VA and a contrast sensitivity chart (CSV-1000) was employed for measuring contrast sensitivity. First, measurements were performed without tinted filters and then using them. Appropriate lenses were given to the patients for 2 days, and they were questioned about their satisfaction using them in different places.Results:A total of 20 male and 31 female patients with mean age of 57.3 years participated in the study. With a 527 ± 10 nm filter, mean VA improved significantly (P ≤ 0.05). Using the 527 ± 10 nm and 511 ± 10 nm filters, mean contrast sensitivity was improved significantly at 3 and 6 cycles/degree frequencies (P < 0.05). The effect of other filters on VA and contrast sensitivity was not significant. Patient satisfaction rate was generally high.Conclusion:Tinted filters are able to rehabilitate low-vision patients due to diabetic retinopathy. The 527 ± 10 and 511 ± 10 nm wavelength filters improved contrast sensitivity and the 527 ± 10 nm filter improved VA to some extent. Further investigations are recommended to assess the effect of these filters in patients with other causes of low-vision.

Reliability in perimetric multichannel contrast sensitivity measurements

BackgroundIn this study, the reliability of perimetric contrast sensitivity measurements favouring the achromatic, the red‐green and the blue‐yellow post‐receptorial mechanisms was analysed.MethodsA new technique, multichannel ATD perimetry, provides spatial and temporal stimuli favouring the detection by an achromatic mechanism (A), from a magno or parvocellular origin or by a red‐green (RG) chromatic mechanism, with a parvocellular origin or a blue‐yellow (BY) mechanism, with a koniocellular origin. The repeatability and reproducibility of contrast sensitivity measurements with these stimuli were studied in a group of 40 healthy subjects. The analysis was carried out on 21 testing points within a 60° by 40° fovea‐centred region of the visual field.ResultsThe within‐observer repeatability for the four mechanisms studied is either good or excellent when the intra‐class correlation coefficient (ICC) can be calculated. For the remaining points, the Friedman's test finds that the measurements are repeatable. The between‐observer reproducibility was either excellent or good in cases where the ICC was applied and according to the Friedman's test all results were reproducible.ConclusionsThe results obtained showed good repeatability and reproducibility with A, RG and BY stimuli, although with BY stimuli repeatability is slightly worse. Future studies on the diagnostic validity of this device are based on the fact that changes of sensitivity can be compared by means of a visual single task, contrast sensitivity measurement and using a common metric.