Showing papers on "Contrast (vision) published in 2004"

Rapid Quantification of Adult and Developing Mouse Spatial Vision Using a Virtual Optomotor System

Abstract: PURPOSE To develop a simple, rapid method of quantifying the spatial vision of mice. METHODS A rotating cylinder covered with a vertical sine wave grating was calculated and drawn in virtual three-dimensional (3-D) space on four computer monitors facing to form a square. C57BL/6 mice standing unrestrained on a platform in the center of the square tracked the grating with reflexive head and neck movements. The spatial frequency of the grating was clamped at the viewing position by repeatedly recentering the cylinder on the head. Acuity was quantified by increasing the spatial frequency of the grating until an optomotor response could not be elicited. Contrast sensitivity was measured at spatial frequencies between 0.03 and 0.35 cyc/deg. RESULTS Grating acuity was measurable on the day of eye opening (postnatal day [P]15: mean acuity, 0.031 cyc/deg) and reached a maximum (approximately 0.4 cyc/deg) by P24. A peak in the contrast sensitivity function emerged on P16 (4.7, or 21% contrast at 0.064 cyc/deg). The peak remained at 0.064 cyc/deg and climbed to a maximum sensitivity of 24.5, or 4% contrast, by P29. Acuity was obtained in each mouse in <10 minutes, and a detailed contrast sensitivity curve was generated in approximately 30 minutes. CONCLUSIONS The virtual optomotor system provides a simple and precise method for rapidly quantifying mouse vision. Behavioral measures of vision in mice are essential for interpreting the results of experiments designed to reveal the cellular and molecular mechanisms of vision and visual development and for evaluating potential treatments for visual diseases.

Ocular Higher-Order Aberrations and Contrast Sensitivity after Conventional Laser In Situ Keratomileusis

Abstract: PURPOSE. To investigate prospectively the relation between induced changes in higher-order aberrations of the eye and changes in contrast sensitivity by conventional laser in situ keratomileusis (LASIK) for myopia. METHODS. In 200 eyes of 110 consecutive patients (mean age, 32.7 8.4 years) undergoing LASIK, ocular aberrations and contrast sensitivity function were determined before and 1 month after surgery. The amount of myopic correction was 5.2 2.8 D (range, 1.0 –13.0). Ocular higher-order aberrations were measured for a 4-mm pupil using the Hartmann-Shack wavefront analyzer (KR-9000PW; Topcon, Tokyo, Japan). The root mean square (RMS) of the third- and fourth-order Zernike coefficients was used to represent coma- and spherical-like aberrations, respectively. Total higher-order aberrations were calculated as the RMS of the third- and fourth-order coefficients. Contrast sensitivity and low-contrast visual acuity were measured. From the contrast sensitivity data, the area under the log contrast sensitivity function (AULCSF) was calculated. RESULTS. LASIK significantly improved logMAR best corrected visual acuity (Wilcoxon signed-rank test, P 0.001), but significantly reduced AULCSF (P 0.001) and low-contrast visual acuity (P 0.007). Total higher-order (P 0.001), coma-like (P 0.001), and spherical-like (P 0.001) aberrations were significantly increased after LASIK. The greater the amount of achieved myopia correction was, the more the changes in contrast sensitivity function and ocular higher-order aberrations were. The induced changes in AULCSF by LASIK showed significant correlations with changes in total higher-order (Pearson r 0.221, P 0.003), coma-like (r 0.205, P 0.006), and spherical-like (r 0.171, P 0.022) aberrations. The changes in logMAR low-contrast visual acuity by surgery significantly correlated with changes in total higher-order (r 0.222, P 0.003), coma-like (r 0.201, P 0.007), and spherical-like (r 0.207, P 0.005) aberrations. CONCLUSIONS. Conventional LASIK significantly increases ocular higher-order aberrations, which compromise the postoperative contrast sensitivity function. (Invest Ophthalmol Vis Sci. 2004; 45:3986 –3990) DOI:10.1167/iovs.04-0629

Functional Imaging of the Human Lateral Geniculate Nucleus and Pulvinar

Abstract: In the human brain, little is known about the functional anatomy and response properties of subcortical nuclei containing visual maps such as the lateral geniculate nucleus (LGN) and the pulvinar. Using functional magnetic resonance imaging (fMRI) at 3 tesla (T), collective responses of neural populations in the LGN were measured as a function of stimulus contrast and flicker reversal rate and compared with those obtained in visual cortex. Flickering checkerboard stimuli presented in alternation to the right and left hemifields reliably activated the LGN. The peak of the LGN activation was found to be on average within +/-2 mm of the anatomical location of the LGN, as identified on high-resolution structural images. In all visual areas except the middle temporal (MT), fMRI responses increased monotonically with stimulus contrast. In the LGN, the dynamic response range of the contrast function was larger and contrast gain was lower than in the cortex. Contrast sensitivity was lowest in the LGN and V1 and increased gradually in extrastriate cortex. In area MT, responses were saturated at 4% contrast. Response modulation by changes in flicker rate was similar in the LGN and V1 and occurred mainly in the frequency range between 0.5 and 7.5 Hz; in contrast, in extrastriate areas V4, V3A, and MT, responses were modulated mainly in the frequency range between 7.5 and 20 Hz. In the human pulvinar, no activations were obtained with the experimental designs used to probe response properties of the LGN. However, regions in the mediodorsal right and left pulvinar were found to be consistently activated by bilaterally presented flickering checkerboard stimuli, when subjects attended to the stimuli. Taken together, our results demonstrate that fMRI at 3 T can be used effectively to study thalamocortical circuits in the human brain.

A fast and adaptive method for image contrast enhancement

Abstract: In this paper we describe a fast approach for image contrast enhancement, based on localized contrast manipulation. Our approach is not only last and easy to implement, but also has several other promising properties (adaptive, multiscale, weighted localization, etc.). We will also discuss in this paper an anisotropic version of our approach. Several examples of medical images, including brain MR images, chest CT images and mammography images, will be provided to demonstrate the performance of our approach.

Blur adaptation and myopia.

Abstract: Previous studies have demonstrated a significant improvement in visual resolution during sustained periods of retinal defocus. This appears to result from perceptual adaptation designed to restore the perceived contrast of the degraded image. However, it is unclear whether perceptual adaptation to sustained blur is present in all individuals or only in certain subgroups, such as those who have been chronically exposed to sustained periods of blur due to uncorrected ametropia. Accordingly, the present study examined the effects of sustained retinal defocus on both high-and low-contrast visual acuity in emmetropes (n = 13) and myopes (n = 18). Subjects were required to view through +2.50-D spherical lenses worn over their distance refractive correction for a continuous 2-hour period. A significant improvement in both Landolt C and grating visual acuity measured through the fogging lenses was observed in both refractive groups. Although the mean change in grating visual acuity was significantly greater for the myopic subjects, the improvements in Landolt C acuity observed in the emmetropes and myopes were statistically equivalent. We hypothesize that the improvement in visual acuity results from perceptual adaptation to the blurred images, which may occur at central sites within the visual cortex.

Spatial vision deficits in infants and children with Down syndrome.

Abstract: purpose. Infants and children with Down syndrome show reduced visual acuity and contrast sensitivity when tested with conventional behavioral techniques. These results may reflect sensory deficits of optical or neural origin or a loss of performance in mechanisms responsible for generating the behavioral response. The purpose of this study was to compare objective acuity and contrast sensitivity measurements recorded with visual-evoked potentials (VEPs), with behavioral clinical test results in a group of children with Down syndrome and a group of control subjects. The goal was to determine whether children with Down syndrome still have a sensory deficit when tested using a procedure that is less cognitively demanding than conventional tests. methods. The subject group comprised 58 children with Down syndrome and 44 control subjects, aged 3 months to 14.15 years. Visual acuity and contrast sensitivity were measured with steady state, swept VEPs and behavioral techniques. VEP acuity was obtained from 36 children with Down syndrome and 40 control subjects, and behavioral acuity from 54 children with Down syndrome and 35 control subjects. VEP contrast sensitivity was measured in 24 children with Down syndrome and 34 control subjects, and behavioral contrast sensitivity in 42 children with Down syndrome and 25 control subjects. Group differences in visual acuity and contrast sensitivity were analyzed with an analysis of covariance (ANCOVA), with age as a covariate. results. Visual acuity thresholds were significantly lower in the group with Down syndrome than in the control group. This was true for both VEP (P < 0.01) and behavioral measures (P < 0.01). The Down syndrome group also had reduced contrast sensitivity when compared with the control subjects, for VEP contrast sensitivity (P < 0.01) and behavioral contrast sensitivity (P < 0.01). The group differences remained when children with ophthalmic anomalies were excluded from the analysis. conclusions. The reduced visual acuity and contrast sensitivity in the Down syndrome group support the idea of an underlying sensory deficit in the visual system in Down syndrome.

Contrast adaptive binarization of low quality document images

Abstract: We propose in this paper an improved method for binarizing document images by adaptively exploiting the local image contrast. The proposed method aims to overcome the common problems encountered in low quality images, such as uneven illumination, low contrast, and random noise. Experiments have been conducted and the results are presented to show the effectiveness of the proposed method.

Psychophysical measurement of neural adaptation abnormalities in magnocellular and parvocellular pathways in glaucoma.

Abstract: PURPOSE. It is well established that contrast sensitivity is reduced in glaucoma. This study explored whether such contrast processing abnormalities consist of an absolute threshold level difference or a problem with contrast gain control. METHODS. Seventeen patients with primary open-angle glaucoma and 17 approximately age-matched control subjects participated. Subjects were tested foveally and midperipherally (12.5°). Subjects with glaucoma were tested in a peripheral region of relatively normal visual field (neighboring locations required to be within the normal 95% confidence limit on the total deviation plot of their most recent SITA/full threshold Humphrey Field Analyzer assessment; Carl Zeiss Meditec, Dublin, CA). Control subjects were tested in matching locations. Contrast discrimination was assessed using the steady-pedestal (magnocellular [M] pathway) and pulsed-pedestal (parvocellular [P] pathway) stimuli of Pokorny and Smith for seven pedestal luminances between 15 and 75 cd/m 2 , presented on a background of 30 cd/m 2 . RESULTS. Glaucoma group thresholds were significantly elevated compared with control subjects foveally and peripherally on both the pulsed-pedestal (P) and steady-pedestal (M) tasks (P 0.01). Effect size statistics revealed slightly greater deficits on the P pathway task and greater deficits for pedestals that were decrements, rather than increments, from the surround luminance. Foveal deficits were of a magnitude to be explained by a reduction in contrast sensitivity; however, the peripheral deficits were greater than predicted by this factor alone. CONCLUSIONS. Foveal and midperipheral dysfunction of both M and P pathways was identified in people with glaucoma, in areas of relatively normal visual field performance. These findings are supportive of nonselective neural adaptation abnormalities in early glaucoma. (Invest Ophthalmol Vis Sci. 2004; 45:1846 –1853) DOI:10.1167/iovs.03-1225

Blur adaptation in myopes.

Abstract: It has been suggested that when subjects with myopia remove their refractive correction, blur adaptation develops to produce an improvement in their visual resolution. The present study measured visual acuity (VA) using high contrast letters and gratings with contrast levels between 2.5% and

Effects of cataract type and location on visual function: The Blue mountains eye study

Abstract: Purpose To measure the effect of cataract type, severity and location on presenting, and best-corrected visual acuity, contrast sensitivity, and glare disability. Methods In all, 3654 (82.4% participation rate) eligible noninstitutionalised residents aged 49 years or older, living in two postcode areas of the Blue Mountains, Australia, received detailed eye examinations including visual acuity, contrast sensitivity, and glare disability testing. Data from right eyes were analysed using multiple regression modelling. Results The effect of age on visual acuity and contrast sensitivity only became evident in persons aged at least 60 years. Cataract severity was inversely related to visual acuity and contrast sensitivity. Late posterior subcapsular cataract caused the greatest reduction in visual acuity. Early grade cataract caused significant reduction in contrast sensitivity at intermediate and high spatial frequencies, but late grade cataract reduced contrast sensitivity across all spatial frequencies. There was insufficient study power to detect consistent significant effect of cataract on glare disability tests or cortical cataract location on visual function. Conclusions Age at least 60 years, cataract type, and cataract severity were principal determinants of visual acuity and contrast sensitivity in this study. Axial and superotemporally located cortical cataract had the greatest effect on visual function tests.

Contrast sensitivity loss with aging: sampling efficiency and equivalent noise at different spatial frequencies.

Abstract: The relative contributions of optical and neural factors to the decrease in visual function with aging were investigated by measurement of contrast detection at three different spatial frequencies, in the presence of external noise, on young and older subjects. Contrast detection in noise functions allows two parameters to be measured: sampling efficiency, which indicates neural changes, and equivalent noise, which demonstrates optical effects. Contrast thresholds were measured in the presence of four levels (including zero) of externally added visual noise. Measurements were obtained from eight young and eight older visually normal observers. Compared with young subjects, older subjects showed significantly (p < 0.05) lower sampling efficiencies at spatial frequencies of 1 and 4 cycles per degree (c/deg) and significantly higher equivalent noise levels for gratings of 10 c/deg. Neural and optical factors affect contrast sensitivity loss with aging differently, depending on the spatial frequency tested, implying the existence of different mechanisms.

Using visual noise to characterize amblyopic letter identification.

Abstract: Amblyopia is a much-studied but poorly understood developmental visual disorder that reduces acuity, profoundly reducing contrast sensitivity for small targets. Here we use visual noise to probe the letter identification process and characterize its impairment by amblyopia. We apply five levels of analysis - threshold, threshold in noise, equivalent noise, optical MTF, and noise modeling - to obtain a two-factor model of the amblyopic deficit: substantially reduced efficiency for small letters and negligibly increased cortical noise. Cortical noise, expressed as an equivalent input noise, varies among amblyopes but is roughly 1.4x normal, as though only 1/1.4 the normal number of cortical spikes are devoted to the amblyopic eye. This raises threshold contrast for large letters by a factor of radical1.4 = 1.2x, a negligible effect. All 16 amblyopic observers showed near-normal efficiency for large letters (> 4x acuity) and greatly reduced efficiency for small letters: 1/4 normal at 2x acuity and approaching 1/16 normal at acuity. Finding that the acuity loss represents a loss of efficiency rules out all models of amblyopia except those that predict the same sensitivity loss on blank and noisy backgrounds. One such model is the last-channel hypothesis, which supposes that the highest-spatial-frequency channels are missing, leaving the remaining highest-frequency channel struggling to identify the smallest letters. However, this hypothesis is rejected by critical band masking of letter identification, which shows that the channels used by the amblyopic eye have normal tuning for even the smallest letters. Finally, based on these results, we introduce a new "Dual Acuity" chart that promises to be a quick diagnostic test for amblyopia.

Contrast-Dependent Spatial Summation in the Lateral Geniculate Nucleus and Retina of the Cat

Abstract: Based on extracellular recordings from 69 lateral geniculate nucleus (LGN) cells in the anesthetized cat, we found spatial summation within their receptive fields to be dependent on the contrast of the stimuli presented. By fitting the summation curves to a difference of Gaussians model, we attributed this contrast-dependent effect to an actual change in the size of the center mechanism. Analogous changes in spatial frequency tuning were also observed, specifically increased peaks and cut-off frequencies with contrast. These effects were seen across the populations of both X and Y cell types. In a few cases, LGN cells were recorded simultaneously with one of their retinal ganglion cell (RGC) inputs (S-potentials). In every case, the RGCs exhibited similar contrast-dependent effects in the space and spatial-frequency domains. We propose that this contrast dependency in the retinal ganglion cells results directly from a reduction in the size of the center mechanism due to an increase in contrast. We also propose that these properties first arise in the retina and are transmitted passively through the LGN to visual cortex.

Video image quality

Abstract: Video image quality may be improved by correcting exposure levels and/or enhancing contrast amounts on each frame. One or more of the following phases may be implemented: skin-color model building, face detecting, exposure level correcting, and contrast enhancing. In a described implementation, a Gaussian skin-color model is built for each image frame during runtime. The Gaussian skin-color model is built with training pixels that are selected responsive to a defined skin color range, which is created offline from manually-selected skin pixels of multiple test sequences. In another described implementation, each pixel of an image frame is re-exposed using a ratio of contrast amount control variables (CACVs). More specifically, a pixel may be converted to a corresponding light intensity using a first CACV, and the corresponding light intensity may be reconverted to a pixel using a second CACV to enhance the contrast and possibly reduce fuzziness of the image frame.

Method for registration of an image applied to digital subtracted angiography

Abstract: In registration of images in digitized subtracted angiography, X-rays irradiate a patient's body. A first digitized mask image is acquired without an injection of the contrast agent into the body, then the contrast agent is injected into the body, and a second digitized contrast image is acquired. The mask image is divided with regular geometrical patterns and a registration is made of the mask image relative to the contrast image through the use of landmarks defined at the corners of the geometrical patterns. These two images are subtracted after registration, and the subtracted image is displayed. The robustness of the landmarks is furthermore tested, and if the robustness is insufficient, a subdivision is made of the regular geometrical patterns.

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

Abstract: 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. 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. 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. 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.

Almost Ideal Contrast Visual Cryptography with Reversing

Abstract: A drawback of visual cryptography schemes (VCS) is much loss of contrast in the reconstructed image This paper shows that no loss of contrast can be almost achieved if we are allowed to use a very simple non-cryptographic operation, reversing black and white Many copy machines have this function these days Therefore, our VCS is very attractive

Normal values for photopic and mesopic letter contrast sensitivity.

Abstract: PURPOSE: The exponential increase of patients having refractive surgery has increased the number of patients with night vision disturbances, such as decreased contrast sensitivity. However, there are no standard contrast sensitivity scales in normal persons in the mesopic range. We describe Pelli-Robson contrast sensitivity under photopic and mesopic luminance conditions in a large Spanish population over a wide range of age groups to provide normal values. A further aim was to evaluate the effect of photopic visual acuity on photopic and mesopic contrast sensitivity. METHODS: A cross-sectional study was performed on 292 participants stratified by age into six groups. Binocular contrast sensitivity was determined with best spectacle correction using the Pelli-Robson letter chart at 1 m under photopic (85 cd/m 2 ) and mesopic (0.15 cd/m 2 ) luminance conditions. RESULTS: Phototopic letter contrast sensitivity began to decrease gradually from the 61 to 70-year-old age group onward, and for mesopic conditions, from the 51 to 60-year-old age group onward. The reduction in mean contrast sensitivity between the oldest and the youngest age groups was 0.20 log units (photopic) and 0.33 log units (mesopic). Loss in contrast sensitivity due to luminance (two successive triplets) increased slightly with age. Both photopic and mesopic letter contrast sensitivity significantly improved as photopic visual acuity increased. CONCLUSIONS: Under mesopic conditions, Pelli-Robson contrast sensitivity began to decline 1 decade earlier than under photopic conditions and was affected by visual acuity. Normal values for mesopic contrast sensitivity could be of help in deciding whether mesopic function is normal or a decrease in contrast sensitivity is pathologic in nature.

Cone-mediated multifocal electroretinogram in early age-related maculopathy and its relationships with subjective macular function tests

Abstract: Purpose. To investigate the multifocal electroretinogram (mfERG) and subjective function in early age-related maculopathy (ARM). Methods. Seventeen subjects with early ARM with visual acuity (VA) of 6/12 or better and 20 age-matched control subjects were examined. We assessed mfERGs, high and low contrast distance VA, near VA, low luminance VA, contrast sensitivity, saturated and desaturated Panel D-15 and visual fields (mean sensitivity). The mfERG responses were analysed by comparing central-overall (method 1) and superior-inferior (method 2) ratios. Results. The mfERG did not discriminate between the groups whereas colour vision (tritan deficiency), contrast sensitivity, and high contrast and low contrast VA showed significantly reduced responses for the early ARM group compared with the control group (p ≤ 0.01). The mfERG first-order kernel responses correlated significantly with the desaturated D-15 in both methods (r = −0.5, p ≤ 0.05). Fundus grading was not correlated with the mfERG measures. Con...

Contrast-based color image segmentation

Abstract: In this letter, we propose a color image segmentation algorithm based on contrast information. Given a color image, we use contrast information, instead of the commonly used derivative information, to detect edges. To fit for human's visual perception, the CIE L/sup */a/sup */b/sup */ color space is used and the /spl Delta/E/sub ab/ color difference is adopted as the measure of color contrast. A subjective experiment is made to demonstrate the weak correlation between the perceived color contrast and the levels of (L/sup */,a/sup */,b/sup */). This experiment implies the feasibility of using a single-threshold scheme to suppress perceptually faint boundaries. A complete segmentation scheme is proposed and the simulation results demonstrate the superiority of this approach in providing reasonable and reliable color image segmentation.

Vision improvement by correcting higher-order aberrations with phase plates in normal eyes.

Abstract: PURPOSE: To psychophysically demonstrate vision improvement when correcting higher-order aberrations with phase plates in normal eyes METHODS: The wavefront aberrations of three nonsurgical normal eyes were measured with a Shack-Hartmann wavefront sensor With these measured aberrations, phase plates were fabricated using a lathing technique Theoretical improvement in retinal image quality was estimated by calculating the optical modulation transfer functions under the white light condition Visual acuity measurements were also conducted to demonstrate improvement in visual performance after correcting higher-order aberrations with the phase plate In this visual acuity measurement, a tumbling “E” with high (100%) and low (10%) contrast was used RESULTS: The phase plate reduced the higherorder root mean square (RMS) wavefront error from 039 ± 009 to 015 ± 002 µm (mean ± standard deviation from three eyes) for a 6-mm pupil With the phase plate, retinal image quality based on the volume of modulation transfer function under 60 cycles per degree (c/deg) was improved by a factor of 18 ± 04 over that of the eyes with spherocylindrical correction only Average improvement in visual acuity achieved by correcting the higherorder aberration was 023 lines with high-contrast letters and 112 lines with low-contrast letters All subjects reported subjective improvement in image quality of the letter with the phase plate CONCLUSION: The phase plate effectively corrected the higher-order aberrations in normal eyes As a result, both retinal image quality and visual acuity especially with the low-contrast letters were improved This study demonstrated the feasibility of correcting higher-order aberrations and improving vision with customized optics [J Refract Surg 2004;20:S523-S527]

Improvement in near visual function after macular translocation surgery with 360-degree peripheral retinectomy.

Abstract: Information is limited on how specific near-vision skills are impacted by therapies such as macular translocation surgery with 360-degree retinectomy (MT360) for age-related macular degeneration (AMD). Standardized tests of near vision were given to 25 consecutive patients with AMD who met entry criteria for this study, preoperatively and 6 and 12 months after MT360. Tests included: near acuity with the Lighthouse chart, timed reading speed using Sloan cards, contrast sensitivity, and color vision. Distance acuity was measured using Bailey–Lovey charts. Measures of preoperative visual function were analyzed to identify those predictive of visual outcomes. Distance acuity was 20/80 or better in 52% of patients at 12 months after surgery, and mean acuity improved from ~20/125 preoperatively to ~20/100 at 12 months. Mean near acuity improved from 3.2±2.5 M before surgery to 1.5±1.0 M at 12 months (significant change of −1.5±2 M, P<0.001). Gain of greater than five numbers in contrast sensitivity at 12 months was also significant (P<0.001). Mean reading speed improved from 41±31 words per minute (wpm) before surgery to 67±44 wpm at 12 months (significant gain of 25±33 wpm, P=0.001). Preoperative distance acuity, near acuity, and reading speed were each predictors of postoperative near visual function. Standardized testing of near visual function provides important predictive and functional outcome data for MT360. MT360 significantly improved near visual function (including near acuity, reading speed and contrast sensitivity) in patients with subfoveal lesions from AMD in the second eye.

Perceived luminance depends on temporal context

Abstract: Brightness--the perception of an object's luminance--arises from complex and poorly understood interactions at several levels of processing. It is well known that the brightness of an object depends on its spatial context, which can include perceptual organization, scene interpretation, three-dimensional interpretation, shadows, and other high-level percepts. Here we present a new class of illusion in which temporal relations with spatially neighbouring objects can modulate a target object's brightness. When compared with a nearby patch of constant luminance, a brief flash appears brighter with increasing onset asynchrony. Simultaneous contrast, retinal effects, masking, apparent motion and attentional effects cannot account for this illusory enhancement of brightness. This temporal context effect indicates that two parallel streams--one adapting and one non-adapting--encode brightness in the visual cortex.