• A number of studies have shown that aspherical IOLs perform better compared to conventional spherical ones in terms of contrast sensitivity (CS), particularly under mesopic conditions [ 2 , 3 ]. (hindawi.com)
  • A meta-analysis of spherical versus aspheric IOLs showed better contrast sensitivity with the latter at all spatial frequencies, most conspicuously under mesopic conditions and with pupillary sizes of 4 mm or greater, as well as reduced overall ocular SA. (crstoday.com)
  • 15 Studies using other aspheric IOLs extended these findings to include better mesopic contrast sensitivity, a higher modulation transfer function cutoff, and lower ocular SA with customization. (crstoday.com)
  • The contrast sensitivity was measured in mesopic and photopic background luminances, with glare (G) levels of 0-2 (G0, G1, and G2, respectively) and spatial frequencies at 1.5, 3, 6, 12, and 18 cycles per degree (cpd). (jkos.org)
  • The CSV-1000-1.5CPD is a special test face designed specifically for Food and Drug Administration clinical trials which require the testing of contrast sensitivity at 1.5 cycles/degree under mesopic lighting conditions. (jutronvision.com)
  • The AcrySof ReSTOR SN6AD3 and Acri.LISA aspheric IOLs provided contrast sensitivity within normal range under photopic conditions and a reduction in contrast sensitivity under mesopic conditions, with no significant differences between the two brands. (fernandez-vega.com)
  • Contrast sensitivity functions show the responses depend on luminance, contrast, spatial and temporal frequency. (apidologie.org)
  • Several studies used VEP to estimate luminance contrast sensitivity in the spatial frequency domain. (bvsalud.org)
  • The transient VEP shows a good agreement with psychophysical measurements of spatial luminance contrast sensitivity and color discrimination, being a noninvasive method to study vision from subjects with difficulty to perform psychophysical tests. (bvsalud.org)
  • Contrast sensitivity, the ability to distinguish the relative difference in luminance of an object from its surrounding or adjacent objects, is a useful measure of visual function. (jkos.org)
  • The chart luminance was regularly checked acuity and Cambridge low-contrast grating using a spot photometer. (who.int)
  • Here we investigate whether ipRGC stimulation in background affects human contrast sensitivity function (CSF), which varies with background luminance. (conf.tw)
  • We measured CSFs at low spatial frequencies in periphery by adopting the silent substitution method to keep background color and luminance silent while manipulating ipRGC stimulation. (conf.tw)
  • 1,2 The data are often gathered by using a scanning slit device to record the spatial variation of luminance across a grating image. (informationdisplay.org)
  • In the study of visual perception, sinusoidal gratings are frequently used to probe the capabilities of the visual system, such as contrast sensitivity. (wikipedia.org)
  • The theory (for which empirical support has yet to be developed) states that in each functional module of the visual cortex, Fourier analysis (or its piecewise form ) is performed on the receptive field and the neurons in each module are thought to respond selectively to various orientations and frequencies of sine wave gratings. (wikipedia.org)
  • The VCTS uses highly controlled advanced photographic and printing techniques to present a series of sine-wave gratings at carefully calibrated levels of contrast. (academy.org.uk)
  • The size of the sine-wave gratings, the contrast levels, and their tilt are all based on current vision science and empirical data. (academy.org.uk)
  • Results: Contrast sensitivity to drifting gratings of very low spatial and temporal frequency was greatly impaired, yet measurable in all patients. (pisavisionlab.org)
  • Contrast sensitivities for horizontal and vertical gratings at spatial frequencies ranging from 1 to 8 cycles per degree (cpd) were measured immediately before and after adaptation to +3.00 diopters cylinder (DC) with-the-rule or against-the-rule astigmatism. (nova.edu)
  • In with-the-rule conditions, contrast sensitivity for horizontal gratings was significantly increased, whereas that for vertical gratings was significantly decreased. (nova.edu)
  • Similarly, in against-the-rule conditions, contrast sensitivity for vertical gratings was significantly increased, whereas that for horizontal gratings was significantly decreased. (nova.edu)
  • At the recommended test distance of 8 ft (2.5 meters), these gratings test the spatial frequencies of 3, 6, 12 and 18 cycles/degree (CPD). (jutronvision.com)
  • At the recommended test distance of 8 feet, the gratings test one spatial frequency of 1.5 cycles/degree. (jutronvision.com)
  • The accommodating group had better contrast sensitivity under photopic conditions at all spatial frequencies ( P ≤.04). (lww.com)
  • Contrast sensitivity function was assessed under photopic conditions. (aston.ac.uk)
  • CS showed a negative correlation with stereopsis under both mesopicand photopic conditions, and a positive correlation with fusional ability at low and intermediate spatial frequencies undermesopic conditions. (kyobobook.co.kr)
  • Both IOLs provided contrast sensitivity within the normal range in photopic conditions. (fernandez-vega.com)
  • Contrast sensitivity is a very important measure of visual function, especially in situations of low light, fog or glare, when the contrast between objects and their background is often reduced. (allaboutvision.com)
  • However, there was no change in contrast sensitivity at any glare level at 12 and 18 cpd after PTK. (jkos.org)
  • Purpose: To determine whether contrast sensitivity (CS) can represent photophobia in intermittent exotropia (IXT) by comparingthe CS test with and without glare stimulus, and to analyze the factors of IXT affecting CS. (kyobobook.co.kr)
  • Results: There was no significant reduction in CS at all spatial frequencies by glare stimulus. (kyobobook.co.kr)
  • Binocular contrast sensitivity function was measured with the Optec 6500 FACT contrast sensitivity chart at distance and at three lighting conditions (85 cd/m2 and 3 cd/m2 with and without glare) in 36 eyes of 18 patients implanted with the AcrySof ReSTOR aspheric SN6AD3 IOL and 40 eyes of 20 patients implanted with the Acri.LISA 366D IOL. (fernandez-vega.com)
  • To Swindale's list may be added: spatial frequency selectivity, patchy intrinsic connectivity and cortical point spread. (paulbourke.net)
  • Afterwards, to examine visual contrast and "selectivity to spatial frequency", sine waves were made to flow across the screen in different angles. (cornerstonecollective.com)
  • In a meta-analysis by Jiwa et al on the examination of nipple discharge fluid, nipple flow cytology had a sensitivity of 75% and a specificity of 87% for benign breast disease. (medscape.com)
  • Model validation showed 99.7% specificity and 10.2% sensitivity for identifying CCHFV circulation areas. (cdc.gov)
  • E-FAST has high sensitivity and specificity (especially in the setting of hypotension), can be done quickly, noninvasively, and without radiation exposure, and may be repeated. (msdmanuals.com)
  • It is classified in transient or steady-state, according with the temporal frequency of stimulation. (bvsalud.org)
  • The SI unit of spatial frequency is the reciprocal metre (m-1), although cycles per meter (c/m) is also common. (wikipedia.org)
  • In image-processing applications, spatial frequency is often expressed in units of cycles per millimeter (c/mm) or also line pairs per millimeter (LP/mm). (wikipedia.org)
  • In these stimuli, spatial frequency is expressed as the number of cycles per degree of visual angle. (wikipedia.org)
  • Each row or circular grouping of patches tests at a specific spatial frequency (cycles per degree), which measures the observer's sensitivity to a particular object size. (academy.org.uk)
  • The test presents ETDRS LogMAR acuity from 20/10 to 20/100 and one row of spatial frequency at 12 cycles/degree. (jutronvision.com)
  • This test presents standard visual acuity from 20/15 to 20/200, two rows of spatial frequencies (6 and 12 cycles/degree) and a real-world driver's scene. (jutronvision.com)
  • According to the contrast sensitivity function [ 13 ], a human observer can discriminate a sine-wave grating of frequency g, which is 4 to 6 cycles per degree (CPD) of visual angle, at the lowest contrast. (springeropen.com)
  • The cutoff frequency C cycles per image used to design the high and lowpass filters, is determined according to the viewing angle θ such that C = θg. (springeropen.com)
  • For reference stimuli at four times the detection contrast, matched contrast ratios were similar across all three groups (P = 0.58). (brad.ac.uk)
  • Determine the CS thresholds in terms of a contrast percentage under the following conditions. (academy.org.uk)
  • The Fourier method will accurately capture the changes in spatial-frequency content and reflect any perceptual differences if they exceed the frequency-dependent thresholds of the HVS. (informationdisplay.org)
  • These spatial measures of information degradation, as well as advancing age also translated to increased baseline contrast thresholds for target detection, orientation discrimination, and feature integration in the masking, crowding, and grouping tasks. (elsevierpure.com)
  • Supported in part by a grant from the Spanish Ministry of Health, Instituto Carlos III, Red Temática de Investigación Cooperativa en Salud Patología Ocular del Envejecimiento, Calidad Visual y Calidad de Vida, Subproyecto de Calidad Visual (RD07/0062). (lww.com)
  • These properties include the spatial frequencies and organisation of: ocular dominance bands, cytochrome oxidase (CO) blobs, singularities and iso-orientation regions. (paulbourke.net)
  • Visual acuity charts only measure the eases, history of previous ocular surgery high frequency component of the contrast or photocoagulation and systemic diseases sensitivity function and are markedly af- other than diabetes. (who.int)
  • A parameter tuning experiment was performed to determine the suitable cutoff frequencies for designing the filter for the MF image. (springeropen.com)
  • All measures of spatial resolution (near and far VA, and peak and cutoff spatial frequency) were found to be reduced with age. (elsevierpure.com)
  • 2021) "Contrast sensitivity deficits in schizophrenia: A psychophysical investigation. (cuny.edu)
  • Contrast sensitivity was tested with best spectacle-corrected visual acuity preoperatively and 3, 6, 12, 18, and 24 months postoperatively. (bvsalud.org)
  • The spatial-frequency theory of vision is based on two physical principles: Any visual stimulus can be represented by plotting the intensity of the light along lines running through it. (wikipedia.org)
  • Further research shows that different spatial frequencies convey different information about the appearance of a stimulus. (wikipedia.org)
  • Originally, a hybrid image was developed as an experimental stimulus to study the human visual system in terms of spatial frequency [ 11 ]. (springeropen.com)
  • According to multiscale perceptual mechanisms of the human visual system, it is possible to present particular spatial frequency information in the image at a certain viewing distance. (springeropen.com)
  • THE Modulation Transfer Function (MTF) or grating modulation versus the spatial frequency of a display system is commonly used as a metric of the ability of the system to faithfully reproduce information as a function of spatial frequency. (informationdisplay.org)
  • In contrast, primates, including humans, macaques, and mouse lemurs, could readily segment figures independent of carrier pattern using the opponent motion cue. (elifesciences.org)
  • musicians and concert-goers often use cannabis to increase sensitivity to music, and anyone who has experienced "the munchies" can attest to a heightened sense of taste. (cornerstonecollective.com)
  • If possible, the patient can be placed in about 5 degrees of Trendelenburg position to increase sensitivity for detection of peritoneal fluid in the right upper quadrant. (msdmanuals.com)
  • Normal values were achieved for low and intermediate spatial frequencies (3 and 6 c/deg). (bvsalud.org)
  • ΔCS was smaller at intermediate spatial frequencies with better fusional ability, greater at high spatialfrequencies with photophobia, and greater at intermediate spatial frequencies with a higher frequency of exotropia. (kyobobook.co.kr)
  • The spatial frequency is a measure of how often sinusoidal components (as determined by the Fourier transform) of the structure repeat per unit of distance. (wikipedia.org)
  • The spectral response of S-cones peak at 420 nm, M-cones at 534 nm, and L-cones at 564 nm, with significant overlap in their spectral response ranges and varying degrees of sensitivity at these range of wavelengths specified by the function m k (λ), k = r, g, b, as depicted in Figure 2.1(a) . (informit.com)
  • where m k (λ) is the wavelength sensitivity function (also known as the color matching function) of the k th cone type or color sensor. (informit.com)
  • We compared the contrast sensitivity of GCD2 patients before and after phototherapeutic keratectomy (PTK) to evaluate the perioperative visual function in these patients. (jkos.org)
  • PURPOSE: To investigate the effect of visual adaptation to orientation-dependent optical blur on meridional contrast sensitivity function in artificially imposed astigmatism. (nova.edu)
  • The conventional test of visual function in AMD is high contrast visual acuity (VA) measurement. (uk.com)
  • i.e. , its response is correlated with the spatial-frequency content of a presented image as determined by the HVS contrast-sensitivity function. (informationdisplay.org)
  • M. Bar (2004) has proposed that low spatial frequencies represent global information about the shape, such as general orientation and proportions. (wikipedia.org)
  • The mappings described allow those properties of the visual field which can be predicted on the basis of spatial contiguity (texture, orientation, colour, contrast) to be available as response properties over the entire visual field. (paulbourke.net)
  • The observer reports the lowest contrast patch visible in each grouping and describes the orientation. (academy.org.uk)
  • The spatial-frequency theory refers to the theory that the visual cortex operates on a code of spatial frequency, not on the code of straight edges and lines hypothesised by Hubel and Wiesel on the basis of early experiments on V1 neurons in the cat. (wikipedia.org)
  • Most neurons in the primary visual cortex respond best when a sine-wave grating of a particular frequency is presented at a particular angle in a particular location in the visual field. (wikipedia.org)
  • The responses of horizontal DNs to contraction and expansion and to unidirectional motion were compared revealing differences in the way they integrate the monocular components of binocular flow-fields and how velocity and spatial structure effects this integration. (apidologie.org)
  • These bars can vary in width (spatial frequency) as well as contrast from target to target, to give a more thorough evaluation of how sensitive your eyes are to differences in contrast. (allaboutvision.com)
  • When the first postoperative examination was not considered, there were no statistically significant differences in contrast sensitivity values at different postoperative periods . (bvsalud.org)
  • To examine differences in spatial pattern of brain activity between color and letter tasks, a representation similarity analysis using correlation coefficient was applied to V1 and V4 voxels. (conf.tw)
  • Research on spatial frequency detection by visual neurons complements and extends previous research using straight edges rather than refuting it. (wikipedia.org)
  • Subsequently, the contrast of a central Gabor was matched to that of a peripheral Gabor with contrast fixed at two times or four times the detection threshold. (brad.ac.uk)
  • Hence, we found that ageing leads to a degradation of the visual information in the form of reduced spatial resolution and efficiency of contrast processing, which coincides with an increase in the distance over which flankers interfere with target detection and discrimination. (elsevierpure.com)
  • Like a standard Snellen visual acuity chart, the Pelli Robson chart consists of horizontal lines of capital letters but instead of the letters getting smaller on each successive line, it is the contrast of the letters (relative to the chart background) that decreases with each line. (allaboutvision.com)
  • Prior to assessing contrast sensitivity (CS) determine distance vision/visual acuity using the Snellen chart. (academy.org.uk)
  • Traditionally this was done using the Snellen chart, which consists of rows of black-on-white high-contrast letters with an unequal number of letters on each line and an unequal change in letter size between lines. (uk.com)
  • Figure 1: Visual acuity in Snellen notation and its conversion to spatial frequency. (uk.com)
  • The grating contrast or spatial frequency for which 50% of infants gave a statistically significant VEP was taken as a measure of threshold. (ox.ac.uk)
  • A person with normal visual acuity but poor contrast sensitivity might see the trees in the foreground clearly (high contrast), but have trouble seeing the contours of the mountains against the sky in the background (low contrast). (allaboutvision.com)
  • A major challenge for spectral-hole-burning filter-based UOT to become useful for in vivo applications, is to identify and develop crystals capable of supporting the required high-contrast filters at wavelengths within the optical window for tissue (~650-950 nm). (lu.se)
  • Diabetes mellitus and its complications gists, focusing on changes of low-contrast have confronted the developing as well as sensitivity in different stages of diabetic the industrialized world as a major public retinopathy. (who.int)
  • Abnormal contrast sensitivity was ob- retinopathy, mild, moderate, severe, or very served in 27.1% of eyes with diabetic retin- severe non-proliferative diabetic retinopa- opathy, compared with 9.0% in unaffected thy (NPDR), early proliferative diabetic eyes. (who.int)
  • Our results indicate that the contrast sensitivity rhythm is modulated by D4Rs via a signaling pathway that involves NPAS2-mediated circadian regulation of Adcy1 . (jneurosci.org)
  • Also techniques and results of reducing speckle contrast by averaging multiple B-scans will be presented. (spie.org)
  • These results suggest possible compensation for sensitivity loss in the visual system. (brad.ac.uk)
  • The results showed that increased ipRGC stimulation enhanced spatial contrast sensitivity while increased cone stimulation decreased it. (conf.tw)
  • RESULTS: Adapting to astigmatic blur enhanced contrast sensitivity at the blurred power meridian but reduced contrast sensitivity at the least affected axis meridian. (nova.edu)
  • If the intended square-wave spatial pattern departs from a 50% duty cycle or if it has a shape that is significantly different than a square-wave (an outcome that is highly likely for projection displays based on matrix image sources), this method will give results that either overestimate or underestimate the perceptually relevant modulation. (informationdisplay.org)
  • It can be difficult to identify a source/cause when mammography is performed due to its poor sensitivity, and variable results have been reported with ultrasound. (medscape.com)
  • In contrast, isokinetic sampling, in which the two velocities are equal, results in an unbiased sample of the stack effluent. (cdc.gov)
  • The findings indicate that spectral hole burning filters may have better contrast-to-noise scaling, and thus potentially greater imaging depths, than other UOT methods such as digital off-axis holography, photorefractive holography, and speckle contrast imaging. (lu.se)
  • To estimate the determinants of spatial variation in Crimean-Congo hemorrhagic fever virus (CCHFV) transmission and to create a risk map as a preventive public health tool, we designed a survey of small domestic ruminants in Andalusia, Spain. (cdc.gov)
  • The Pelli Robson contrast sensitivity chart tests your ability to detect letters that are gradually less contrasted with the white background as your eyes move down the chart. (allaboutvision.com)
  • Conventional letters are ideal as targets to measure errors of refraction since they are particularly vulnerable to the effects of spurious resolution caused by optical defocus as a result of phase reversals within their rich spatial frequency spectra, resulting in the letter quickly becoming harder to resolve with decreasing angular size. (uk.com)
  • A more user friendly approach is to score in terms of contrast percentage. (academy.org.uk)
  • Conversely, some people achieve better contrast sensitivity and night vision after LASIK, compared with their vision with glasses or contact lenses before the procedure. (allaboutvision.com)
  • Hence, many imaging system design choices and parameters, including spatial and temporal resolution as well as color representation, have been inspired by or selected to imitate the properties of human vision. (informit.com)
  • Nevertheless, few studies have examined whether ipRGCs also affect spatial vision. (conf.tw)
  • Our findings indicate that, contrary to previous findings that ipRGCs contribute mainly to non-visual functions, ipRGCs also contributed to fundamental properties of spatial vision. (conf.tw)
  • Brief exposure to astigmatic blur altered contrast sensitivity in the opposite direction at the two principal meridians, indicating that the mature visual system possesses functional plasticity to recalibrate the response characteristics of orientationally tuned cortical filters and thus promote substantial reductions of meridional anisotropy in astigmatic vision, to some extent counterbalancing the elongated oval shape of astigmatic blur. (nova.edu)
  • Spatial frequency is simply the level of detail observed per degree of visual angle, or in other words, how much detail the rodents are seeing in each section of their total vision. (cornerstonecollective.com)
  • Contrast sensitivity after posterior chamber phakic intraocular lens implantation for high myopia. (bvsalud.org)
  • To evaluate contrast sensitivity after posterior chamber phakic intraocular lens (PIOL) implantation for the correction of high myopia . (bvsalud.org)
  • Contrast sensitivity increased after posterior chamber phakic intraocular lens implantation (Staar ICL) in all spatial frequencies when compared to preoperative contrast sensitivity (best spectacle-corrected). (bvsalud.org)
  • A contrast sensitivity test measures your ability to distinguish between finer and finer increments of light versus dark (contrast). (allaboutvision.com)
  • Contrast sensitivity (CS) is the ability to identify and distinguish objects without a clear outline from their background contrast. (visioncenter.org)
  • The perceived color of light f ( x 1 , x 2 , λ) at spatial location ( x 1 , x 2 ) depends on the distribution of energy in the wavelength λ dimension. (informit.com)
  • Experimental values of the filter contrast obtained in UOT measurements in this wavelength range have so far been limited to 14 dB. (lu.se)
  • Visual impairment was evaluated by means of psychophysical testing, where patients were asked to discriminate the drifting direction of a contrast modulated grating. (pisavisionlab.org)
  • These two factors together resulted in a substantial systematic reduction, averaging 34%, in meridional anisotropy of contrast sensitivity across the spatial frequency spectrum. (nova.edu)