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Clinical Sciences |

Deficits in Perception of Images of Real-World Scenes in Patients With a History of Amblyopia FREE

Giuseppe Mirabella, PhD; Sam Hay, MD; Agnes M. F. Wong, MD, PhD, FRCSC
[+] Author Affiliations

Author Affiliations: Departments of Ophthalmology and Vision Sciences, University of Toronto (Dr Mirabella and Wong) and The Hospital For Sick Children (Dr Wong), Toronto, Ontario, Canada. Dr Hay is in private practice in Huntsville, Alabama.


Arch Ophthalmol. 2011;129(2):176-183. doi:10.1001/archophthalmol.2010.354.
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Published online

Objectives  To investigate the perception of images of real-world scenes in patients with amblyopia and to compare their performance with that of visually normal participants by viewing conditions (monocular vs binocular) and by treatment outcomes (successfully vs unsuccessfully treated vs normal eyes).

Methods  Thirty-nine healthy and 26 amblyopic individuals who had undergone previous amblyopia treatment were recruited to perform a match-to-sample task that used images of real-world scenes. Rates of correct, incorrect, and no responses and mean reaction time were recorded.

Results  Performance during monocular viewing showed that the mean correct response rate was 59% in the amblyopic eyes, 62% in the fellow eyes, and 67% in the normal eyes (P = .008). During binocular viewing, the correct response rate remained reduced at 58% in amblyopic patients compared with 68% in participants with normal vision (P = .03). Performance by treatment outcomes showed that the mean correct response rate was 59% in the unsuccessfully treated group, 64% in the successfully treated group, and 67% in the normal group (P = .002). There was no difference in performance among amblyopia subtypes.

Conclusions  Real-world scene perception is impaired in amblyopia, with the poorest performance during amblyopic monocular and binocular viewing. Despite successful treatment of the amblyopic eye to normal acuity levels, perception of images in real-world scenes remains deficient in patients with a history of amblyopia.

Figures in this Article

Amblyopia is a visual impairment of 1 or both eyes caused by inadequate use during early childhood that cannot be corrected immediately by optical means.1 It is estimated to affect 3% to 5% of people in the Western world and is the primary cause of monocular blindness.28 Amblyopia is associated most commonly with early childhood strabismus (eye misalignment), anisometropia (difference in refractive errors between the 2 eyes), or both (ie, mixed mechanisms). In addition to deficits in visual acuity and contrast sensitivity,911 amblyopic patients show abnormal higher-level perception, including deficits in global form and motion integration,1216 global contour processing,1618 second-order motion detection,1921 Vernier acuity/positional uncertainty,11 symmetry detection,22 and other types of complex motion detection.23 Deficits on tasks that involve higher-order attentional components, including underestimation in a visual object enumeration task,24 prolonged attentional blink,25 and decreased accuracy when tracking single or multiple objects,26 are also evident in amblyopic patients. In addition, the fellow eye in amblyopic patients demonstrates smaller deficits in contrast sensitivity,27 Vernier acuity/positional uncertainty,2830 contour detection or detection of second-order image characteristics,19,31,32 and detection of motion-defined form33,34 exist concurrently with deficits in the amblyopic eye.

In previous studies934 of visual deficits in amblyopia, the investigators have focused on specific aspects of vision and performed experiments to test the variables relevant to their hypotheses. However, a major question that remains unexplored is whether amblyopia affects the perception of objects and scenes during everyday activities. In the present study, we showed amblyopic patients a sample image consisting of an everyday scene or object and asked them to match it to an identical image among a group of similar “distractor” images. Our first goal was to assess how well amblyopic patients identified and matched images of real-world scenes and to compare their performance with that of participants with normal visual acuity (hereinafter referred to as visually normal participants) during different viewing conditions, namely, monocular viewing (amblyopic vs fellow vs normal eyes) and binocular viewing (amblyopic patients vs visually normal participants). In this report, fellow eye refers to the nonamblyopic eye of amblyopic patients, and normal eye refers to eyes of visually normal participants.

A second goal of this study was to determine whether successful treatment of the amblyopic eye by clinical criteria had any influence on the perception of images of real-world scenes. Many previous studies11,16,26,28,31,3537 have examined the visual deficits in amblyopia by combining patients with and without previous treatment. Those studies did not investigate specifically whether other visual deficits remained after successful treatment by acuity criteria (ie, after visual acuity improves to normal) or whether the severity of these deficits differed between successfully and unsuccessfully treated eyes. In this study, we investigated whether the perception of images of real-world scenes differs between successfully treated eyes and normal eyes with the same acuity level (20/25 or better) and between successfully and unsuccessfully treated eyes that underwent previous amblyopia treatment.

PARTICIPANTS

Twenty-six amblyopic patients and 39 visually normal individuals aged 9 to 65 years were recruited from a private practice of one of us (S.H.). For the purpose of this study, amblyopia was defined as a visual acuity of 20/40 or worse in the amblyopic eye and an interocular difference of 2 or more chart lines at diagnosis. Strabismic amblyopia was defined as amblyopia in the presence of eye misalignment at distance, near fixation, or both. Refractive/anisometropic amblyopia was defined as amblyopia in the presence of a difference in refractive error between the 2 eyes of 0.50 diopters (D) or more of spherical equivalent or a difference in astigmatism in any meridian of 1.50 D or more. Mixed-mechanism amblyopia was defined as amblyopia in the presence of a combination of strabismus and anisometropia. People with any ocular cause of reduced visual acuity, high myopia (−6.00 D or more), or prior intraocular surgery were excluded from the study. All amblyopic patients had undergone previous treatment (eg, glasses, monocular occlusion, penalization, strabismus surgery, or any combination of these treatments). Best-corrected visual acuity was recorded at diagnosis and at the time of the experiment. Treatment success was defined as achieving a visual acuity of 20/25 or better in the amblyopic eye or an interocular difference of 1 line or less. Visually normal participants had a visual acuity of 20/25 or better in both eyes and normal binocular vision (≤40 arc seconds). The research protocol adhered to the tenets of the Declaration of Helsinki. Informed consent was obtained from all participants.

IMAGE SELECTION

Images were chosen from a database of more than 1400 images taken by the experimenters. Although images used within a particular trial were highly similar (in their perspective or in the similarity of the objects), across trials the images were diverse and nonspecific. These pictures were made up of everyday scenes indoors or outdoors and of varying textures or objects and were taken from relatively near or far distances.

Of the total database of images, a subset of 320 was chosen for a match-to-sample task (a sample of these images is shown in Figure 1). This subset was chosen on the basis of image quality and similarity. Effort was also made to include as diverse a range of images as possible in this subset to reflect a realistic range of perspectives an individual living in North America might encounter.

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Figure 1.

A sample of images used in the match-to-sample task.

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PROCEDURE

All participants performed a match-to-sample task. For those with amblyopia, affected and fellow eyes were tested separately in a random order. Those in the control group had 1 randomly chosen eye tested for comparison. Participants were seated 70 cm in front of a computer monitor. Eighty trials were randomly shown during the task. Each trial consisted of a reference image shown on the right side of the screen subtending a visual angle of 8°. Simultaneously, on the left side of the screen, 4 choices were displayed in a 2 × 2 array, each within a circular aperture that was 5° in diameter (Figure 2). One of these 4 choices was identical to the reference image, whereas the other 3 choices resembled the reference image but were not identical to it. That is, the incorrect choices were of the same object or scene but taken from a different perspective or were of a similar but not identical object. Overall, the correct response rate of all participants ranged from 31% to 90%; thus, the difficulty level of the 80 trials varied considerably, with some individual trials consistently being easier and others more difficult to complete.

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Figure 2.

Each trial consisted of a reference image displayed on the right side of the screen subtending a visual angle of 8°. Simultaneously, on the left side of the screen, 4 choices were shown in a 2 × 2 array, each within a circular aperture that was 5° in diameter. One of these 4 choices was identical to the reference image, whereas the other 3 resembled the reference image but were not identical to it. In this particular trial shown, the choice at the lower left was identical to the reference image on the right, and an overall correct response rate of 57% was obtained across all participants.

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Each trial was shown for 5 seconds, during which the reference image and the 2 × 2 array were viewed freely. Participants used a mouse-click to select the choice that they thought matched the reference image. If they did not respond within the 5-second period, the trial ended and was scored as no response, and the following trial began immediately.

DATA ANALYSIS

The rates of correct, incorrect, and no responses were calculated in percentages from the 80 trials for each participant. The mean reaction time for each correct response was also recorded. These 4 performance measures were compared among the 3 monocular viewing conditions (amblyopic eye, fellow eye, and normal eye) and the 2 binocular viewing conditions (amblyopic patients and visually normal participants) using analyses of variance (ANOVAs). These 4 performance measures were also compared among treatment outcomes of the amblyopic eyes (failure and success) and the normal eyes and among amblyopia subtypes (strabismic, refractive/anisometropic, and mixed-mechanism) by means of ANOVAs.

To assess whether performances systematically worsen from the normal eye to the fellow eye to the amblyopic eye, contrast analyses were conducted for all significant ANOVAs. To examine whether the differences in performances among the amblyopic, fellow, and normal eyes were due to differences in visual acuity, correlation coefficients were calculated between mean correct response rate and best-corrected visual acuity. Unless otherwise indicated, data are expressed as mean (SD).

The mean age was 38.0 (20.6) (range, 9-64) years for the amblyopic patients and 37.1 (17.9) (range, 10-64) years for visually normal participants (unpaired, 2-tailed t test, P = .85). Ten of the 26 amblyopic patients (39%) had strabismic amblyopia, 13 (50%) had refractive/anisometropic amblyopia, and 3 (12%) had mixed-mechanism amblyopia. At the time of the experiment, best-corrected visual acuity in the treated amblyopic eye was 20/25 or better in 8 (31%), 20/30 to 20/40 in 12 (46%), 20/50 to 20/80 in 4 (15%), and 20/100 to 20/200 in 2 (8%) of the amblyopic patients. Thus, 8 of 26 amblyopic patients (31%) had successful treatment (ie, 20/25 or better), whereas 18 (69%) had failed treatment (ie, 20/30 or worse).

PERFORMANCE BY VIEWING CONDITIONS
Monocular Viewing

The mean correct, incorrect, and no response rates for the 3 monocular viewing conditions are shown in Figure 3. A significant difference in correct response rates was found among the 3 monocular viewing conditions, including 59% (9%) during amblyopic eye viewing, 62% (9%) during fellow eye viewing, and 67% (10%) during normal eye viewing (F2,24 = 5.88; P = .008). There was a significant increase in the correct response rates from amblyopic eye to fellow eye to normal eye (F1,24 = 10.73; P = .003). The difference in correct response rates was not due to a difference in visual acuity; the correlation coefficient between correct response rates and best-corrected visual acuity was not significant (r = −0.20; P = .29).

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Figure 3.

Performance by viewing eye showing the mean rates of correct, incorrect, and no responses during viewing with amblyopic, fellow, and normal eyes. Error bars represent 1 SD.

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Incorrect response rates were similar among the 3 monocular viewing conditions, including 28% (10%) during amblyopic eye viewing, 28% (9%) during fellow eye viewing, and 26% (10%) during normal eye viewing (F2,24 = 0.53; P = .60). However, a significant difference in no response rates was found: 13% (10%) during amblyopic eye viewing, 10% (9%) during fellow eye viewing, and 7% (5%) during normal eye viewing (F2,24 = 5.39; P = .01). Again, there was a significant decrease in no response rates from viewing in amblyopic eyes to fellow eyes to normal eyes (F1,24 = 10.49; P = .004).

A comparison of mean reaction times showed no differences among the 3 monocular viewing conditions: 2.7 (0.5) seconds during amblyopic eye viewing, 2.6 (0.5) seconds during fellow eye viewing, and 2.6 (0.4) seconds during normal eye viewing (F1,24 = 0.13; P = .86).

Binocular Viewing

During binocular viewing, a significant difference in correct response rates was found between amblyopic patients (58% [8%]) and visually normal participants (68% [10%]; F1,65 = 5.02; P = .03). There were no differences in any of the other performance measures (incorrect responses, no responses, and mean reaction time) between the amblyopic patients and visually normal participants.

Subgroup analysis showed no significant differences in any of the 4 performance measures among different amblyopia subtypes during monocular or binocular viewing, which may be a result of the small sample size in each subtype.

PERFORMANCE BY TREATMENT OUTCOMES

The mean rates of correct, incorrect, and no responses for the 2 treatment outcomes of amblyopic and normal eyes are shown in Figure 4. A significant difference in correct response rates was observed at 59% (10%) in the unsuccessfully treated group, 64% (6%) in the successfully treated group, and 67% (10%) in the visually normal group (F2,24 = 7.09; P = .002). There was a significant increase in the percentage of correct rates from the unsuccessfully treated group to the successfully treated group to the visually normal group (F1,24 = 14.10; P < .001).

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Figure 4.

Performance by treatment outcomes of the amblyopic eye showing the mean rates of correct, incorrect, and no responses in the unsuccessfully treated, successfully treated, and normal groups. Error bars represent 1 SD.

Graphic Jump Location

Incorrect response rates were similar among the 3 groups, at 29% (9%) in the unsuccessfully treated group, 26% (6%) in the successfully treated group, and 26% (9%) in the visually normal group (F2,24 = 0.97; P = .38). However, a significant difference in no response rates were found: 12% (10%) in the unsuccessfully treated group, 10% (7%) in the successfully treated group, and 7% (5%) in the visually normal group (F2,24 = 5.22; P = .008). Again, there was a significant decrease in no response rates from the unsuccessfully treated group to the successfully treated group to the visually normal group (F2,24 = 10.43; P = .002).

A comparison of mean reaction times showed no differences among the 2 treatment outcomes of amblyopic and normal eyes at 2.6 (0.5) seconds in the unsuccessfully treated group, 2.8 (0.5) seconds in the successfully treated group, and 2.6 (0.4) seconds in the visually normal group (F1,24 = 1.63; P = .26).

In previous studies934 of visual deficits in amblyopia, certain predetermined aspects of visual function (eg, acuity, contrast sensitivity, and global contour processing) were tested by using stimuli specifically designed for use in the laboratory. In this study, we endeavored to broaden the scope of amblyopia research by investigating whether perception of images of real-world scenes is also affected in amblyopic patients during a match-to-sample task. We found that patients with amblyopia performed significantly worse than visually normal participants, with lower correct response rates during amblyopic eye viewing than during fellow eye viewing. The poor performance remained when amblyopic patients were tested binocularly. In addition, the difference in performance among viewing eyes was not due to a difference in visual acuity. To the best of our knowledge, this is the first study to document visual dysfunction during viewing of images of real-world scenes in amblyopia.

Some amblyopia treatment studies3843 have defined success as the attainment of a visual acuity of 20/30 or 20/40 by the end of the treatment period, whereas others4448 have adopted a more strict criterion of 20/20 or 20/25 (normal or near-normal visual acuity) as their definition of success. We defined treatment success using the latter, more stringent criteria for 2 reasons. First, from a functional viewpoint, the best condition that promotes normal binocular visual development is when the visual input from each eye is equal.49 Second, by using the same visual acuity criterion for successfully treated patients and visually normal participants, we ensured that any difference in performance between successfully treated and normal eyes was not due to a difference in their visual acuity. We found that perception of images of real-world scenes in the successfully treated eye was significantly worse than in the normal eye. Our results provide support that visual deficits other than high-contrast visual acuity remained despite achievement of normal to near-normal visual acuity after current amblyopia therapy.

It has been proposed that, during binocular viewing, the inputs from both eyes contain correlated stimulus signals and that they summate during visual processing, whereas the noise signals in the stimulus from each eye are uncorrelated, effectively canceling each other out. As a result, the signal to noise ratio in the stimulus signals increases during binocular viewing, which, in turn, leads to better visual performance.50 However, this binocular advantage was not evident in patients with amblyopia, as indicated by the observation that their performance during binocular viewing was no better than that during amblyopic eye viewing. This may be due to a disruption of binocular organization and a loss of binocularity in neurons in the visual cortex in amblyopia.5154 However, a recent study demonstrated that binocular summation of contrast sensitivity is normal in people with strabismic amblyopia, when stimulus contrast is adjusted to equalize visibility of the gratings for the 2 eyes,55 suggesting that the binocular summation deficits seen in previous studies54,5661 may result from interocular differences in contrast sensitivity between the eyes.

Visual processing is generally believed to be divided into the dorsal (the “where” or magnocellular) and ventral (the “what” or parvocellular) pathways. Visual information enters the ventral pathway through the primary visual cortex (V1), projecting through V2 and V4 to the inferior temporal cortex. The ventral pathway is believed to be primarily concerned with object recognition through integrating features,62 and it is also responsible for detection of second-order motion (including spatiotemporal scene variation of contrast and depth but not luminance) and biological motion.63,64 Global visual tasks fall generally into 1 of 2 categories. The first is feature integration, a process during which adjacent elements in the visual field are identified and grouped as belonging to the same object.15,65,66 The second is image segregation, a process during which an object is identified as a whole and parsed from its background.67 Patients with amblyopia have deficits in feature integration13,15,66 and image segregation tasks.6870 In addition, crowding or spatial interference is a well-documented characteristic of amblyopia28,71,72 that involves detection of simple features and feature integration.73,74 There is an ongoing debate, however, as to whether these deficits in higher-level global visual function in amblyopia are a result of abnormal processing in extrastriate areas that are affected directly by early abnormal visual experience, whether these deficits are a cascade downstream effect resulting from poor, suboptimal visual inputs from early visual areas, or whether they are both.15,66 These deficits in global visual tasks remain abnormal in amblyopia even after visual acuity and contrast sensitivity deficits have been taken into account,15,66 indicating that these deficits occur primarily in extrastriate areas and are independent of abnormal inputs from V1.

Although the results of our current study demonstrated that perception of images of real-world scenes is affected in patients with amblyopia, what remains to be elucidated is whether these abnormalities in real-world scene perception are associated with deficits in acuity and other lower-level visual processes or are associated with higher-level perceptual deficits. In people with normal vision, factors such as contrast gain control75 and other image statistics7681—processes that occur primarily in V18284—are important for contour and feature detection of objects during real-world scene perception. Contrast gain control describes the responses of a V1 neuron that could be modulated by contrast or orientation outside its classic receptive field.75 For example, a neuronal response is enhanced if nearby lines of similar contrast and orientation are identified as belonging to the same edge.75 Contrast gain control plays a major role in determining how easily an object is identified, by normalizing across contrast levels of an image, thereby allowing edge or feature detection among many objects of differing contrasts.75 Other image statistics, such as local similarities in orientation and spatial frequency content, are also important for contour and feature detection.7681 Analyses of the statistical properties of real-world images have demonstrated that the orientations of nearby contours are highly correlated with one another and that there is a high collinearity in the contours and edges belonging to the same edge or object.81 Single-cell responses in neurons in V1 of animals82,83 and behavioral performance in humans76,85,86 suggest that the visual system has evolved to use these statistics for feature extraction.

Effective real-world scene perception is also dependent on processes that occur in areas beyond V1. Processes that are related to boundary and edge detection of textures and objects have been identified in cats and primates as early as areas analogous to the human V2.87,88 Primate single-cell and human imaging studies have identified areas related to object perception in the V3A area and lateral occipital cortex8992 and extending into the inferior temporal cortex.91,92 In addition, people with normal vision are very efficient at extracting categorical information from complex real-world scenes (eg, detecting the presence of object categories such as plants or furniture)77,9395 despite the fact that different classes of real-world scenes often share similar image statistics.96 Recent studies using functional magnetic resonance imaging have shown that the parahippocampal place area, retrosplenial cortex, and lateral occipital complex all contribute to real-world scene categorization by humans.96,97

It is possible that the deficits that we demonstrated in this pilot study are related to disruptions of visual processing in V1; the early extrastriate areas; the cortex specialized for objects (lateral occipital cortex), scenes (parahippocampal place area), and faces (fusiform face area); or a combination of these areas. Accumulating research suggests that higher-order tasks that require attention, above and beyond the influence of deficits attributable to V1, are also affected in amblyopic patients.2426 Further studies using real-world scene perception paradigms adapted from studies of visually normal participants (eg, free recall, forced-choice recognition, visual priming paradigms, and paradigms with variable stimuli presentation time and a shorter time window for response)77,86,98102 will shed light on this issue. Neuroimaging with high temporal (eg, magnetoencephalography) and spatial (eg, functional magnetic resonance imaging) resolution96,97,103,104 will further clarify the relative role of lower- and higher-level visual processing in contributing to the deficits in real-world scene perception in amblyopia.

In summary, this is the first study to demonstrate that people with amblyopia have impaired perception of images of real-world scenes. In addition, our findings provide support that visual functions other than high-contrast visual acuity remain deficient despite successful amblyopia therapy using clinical criteria. Together with the growing evidence that people with amblyopia often have poor motor performance and eye-hand coordination,105108 our results show that amblyopia affects many aspects of a person's everyday life, including perception of real-world scenes. Clinicians should be aware of these deficits when providing counseling to patients and their parents.

Correspondence: Agnes M. F. Wong, MD, PhD, FRCSC, Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, 555 University Ave, Toronto, ON M5G 1X8, Canada (agnes.wong@utoronto.ca).

Submitted for Publication: April 7, 2010; final revision received May 19, 2010; accepted June 2, 2010.

Financial Disclosure: None reported.

Funding/Support: This study was supported by grants MOP 89763 and MOP 57853 from the Canadian Institutes of Health Research, a Leaders Opportunity Fund from the Canada Foundation for Innovation, and the Department of Ophthalmology and Vision Sciences at The Hospital for Sick Children (all to Dr Wong).

American Academy of Ophthalmology,Amblyopia: Preferred Practice Pattern. San Francisco, CA American Academy of Ophthalmology2007;
Brown  SAWeih  LMFu  CLDimitrov  PTaylor  HR McCarty  CA Prevalence of amblyopia and associated refractive errors in an adult population in Victoria, Australia. Ophthalmic Epidemiol 2000;7 (4) 249- 258
PubMed
Hillis  A Amblyopia: prevalent, curable, neglected. Public Health Rev 1986;14 (3-4) 213- 235
PubMed
Preslan  MWNovak  A Baltimore Vision Screening Project. Ophthalmology 1996;103 (1) 105- 109
PubMed
Krueger  DEEderer  FReport on the National Eye Institute's Visual Acuity Impairment Survey Pilot Study. Bethesda, MD Office of Biometry and Epidemiology, National Eye Institute1984;
Vinding  TGregersen  EJensen  ARindziunski  E Prevalence of amblyopia in old people without previous screening and treatment: an evaluation of the present prophylactic procedures among children in Denmark. Acta Ophthalmol (Copenh) 1991;69 (6) 796- 798
PubMed
Buch  HVinding  TLa Cour  MNielsen  NV The prevalence and causes of bilateral and unilateral blindness in an elderly urban Danish population: the Copenhagen City Eye Study. Acta Ophthalmol Scand 2001;79 (5) 441- 449
PubMed
Attebo  KMitchell  PCumming  RSmith  WJolly  NSparkes  R Prevalence and causes of amblyopia in an adult population. Ophthalmology 1998;105 (1) 154- 159
PubMed
Levi  DMHarwerth  RS Spatio-temporal interactions in anisometropic and strabismic amblyopia. Invest Ophthalmol Vis Sci 1977;16 (1) 90- 95
PubMed
Hess  RFHowell  ER The threshold contrast sensitivity function in strabismic amblyopia: evidence for a two type classification. Vision Res 1977;17 (9) 1049- 1055
PubMed
Levi  DMWaugh  SJBeard  BL Spatial scale shifts in amblyopia. Vision Res 1994;34 (24) 3315- 3333
PubMed
Simmers  AJLedgeway  THess  RF McGraw  PV Deficits to global motion processing in human amblyopia. Vision Res 2003;43 (6) 729- 738
PubMed
Simmers  AJBex  PJ The representation of global spatial structure in amblyopia. Vision Res 2004;44 (5) 523- 533
PubMed
Simmers  AJLedgeway  THess  RF The influences of visibility and anomalous integration processes on the perception of global spatial form versus motion in human amblyopia. Vision Res 2005;45 (4) 449- 460
PubMed
Mansouri  BHess  RF The global processing deficit in amblyopia involves noise segregation. Vision Res 2006;46 (24) 4104- 4117
PubMed
Levi  DMYu  CKuai  SGRislove  E Global contour processing in amblyopia. Vision Res 2007;47 (4) 512- 524
PubMed
Hess  RF McIlhagga  WField  DJ Contour integration in strabismic amblyopia: the sufficiency of an explanation based on positional uncertainty. Vision Res 1997;37 (22) 3145- 3161
PubMed
Chandna  APennefather  PMKovács  INorcia  AM Contour integration deficits in anisometropic amblyopia. Invest Ophthalmol Vis Sci 2001;42 (3) 875- 878
PubMed
Wong  EHLevi  DM McGraw  PV Is second-order spatial loss in amblyopia explained by the loss of first-order spatial input? Vision Res 2001;41 (23) 2951- 2960
PubMed
Wong  EHLevi  DM Second-order spatial summation in amblyopia. Vision Res 2005;45 (21) 2799- 2809
PubMed
Mansouri  BAllen  HAHess  RF Detection, discrimination and integration of second-order orientation information in strabismic and anisometropic amblyopia. Vision Res 2005;45 (18) 2449- 2460
PubMed
Levi  DMSaarinen  J Perception of mirror symmetry in amblyopic vision. Vision Res 2004;44 (21) 2475- 2482
PubMed
Simmers  AJLedgeway  TMansouri  BHutchinson  CVHess  RF The extent of the dorsal extra-striate deficit in amblyopia. Vision Res 2006;46 (16) 2571- 2580
PubMed
Sharma  VLevi  DMKlein  SA Undercounting features and missing features: evidence for a high-level deficit in strabismic amblyopia. Nat Neurosci 2000;3 (5) 496- 501
PubMed
Asper  LJCrewther  DPCrewther  S Do different amblyopes have different attentional blinks [ARVO abstract]? Invest Ophthalmol Vis Sci 1 May2003;44S4094
Ho  CSPaul  PSAsirvatham  ACavanagh  PCline  RGiaschi  DE Abnormal spatial selection and tracking in children with amblyopia. Vision Res 2006;46 (19) 3274- 3283
PubMed
Leguire  LERogers  GLBremer  DL Amblyopia: the normal eye is not normal. J Pediatr Ophthalmol Strabismus 1990;27 (1) 32- 39
PubMed
Levi  DMKlein  SA Vernier acuity, crowding and amblyopia. Vision Res 1985;25 (7) 979- 991
PubMed
Cox  JFSuh  SLeguire  LE Vernier acuity in amblyopic and nonamblyopic children. J Pediatr Ophthalmol Strabismus 1996;33 (1) 39- 46
PubMed
Bedell  HEFlom  MCBarbeito  R Spatial aberrations and acuity in strabismus and amblyopia. Invest Ophthalmol Vis Sci 1985;26 (7) 909- 916
PubMed
Kovács  IPolat  UPennefather  PMChandna  ANorcia  AM A new test of contour integration deficits in patients with a history of disrupted binocular experience during visual development. Vision Res 2000;40 (13) 1775- 1783
PubMed
Chandna  AGonzalez-Martin  JANorcia  AM Recovery of contour integration in relation to logMAR visual acuity during treatment of amblyopia in children. Invest Ophthalmol Vis Sci 2004;45 (11) 4016- 4022
PubMed
Giaschi  DERegan  DKraft  SPHong  XH Defective processing of motion-defined form in the fellow eye of patients with unilateral amblyopia. Invest Ophthalmol Vis Sci 1992;33 (8) 2483- 2489
PubMed
Kelly  SLBuckingham  TJ Movement hyperacuity in childhood amblyopia. Br J Ophthalmol 1998;82 (9) 991- 995
PubMed
Hess  RFDemanins  R Contour integration in anisometropic amblyopia. Vision Res 1998;38 (6) 889- 894
PubMed
Ho  CSGiaschi  DE Stereopsis-dependent deficits in maximum motion displacement in strabismic and anisometropic amblyopia. Vision Res 2007;47 (21) 2778- 2785
PubMed
Levi  DMKlein  SAYap  YL Positional uncertainty in peripheral and amblyopic vision. Vision Res 1987;27 (4) 581- 597
PubMed
Pediatric Eye Disease Investigator Group, A randomized trial of atropine vs patching for treatment of moderate amblyopia in children. Arch Ophthalmol 2002;120 (3) 268- 278
PubMed
Hiscox  FStrong  NThompson  JRMinshull  CWoodruff  G Occlusion for amblyopia: a comprehensive survey of outcome. Eye (Lond) 1992;6 (pt 3) 300- 304
PubMed
Latvala  MLPaloheimo  MKarma  A Screening of amblyopic children and long-term follow-up. Acta Ophthalmol Scand 1996;74 (5) 488- 492
PubMed
Flynn  JTCassady  JC Current trends in amblyopia therapy. Ophthalmology 1978;85 (5) 428- 450
PubMed
Kutschke  PJScott  WEKeech  RV Anisometropic amblyopia. Ophthalmology 1991;98 (2) 258- 263
PubMed
Robinson  J Simple anisometropia and amblyopia. Br Orthopt J 1961;1813- 26
Lithander  JSjöstrand  J Anisometropic and strabismic amblyopia in the age group 2 years and above: a prospective study of the results of treatment. Br J Ophthalmol 1991;75 (2) 111- 116
PubMed
Epelbaum  MMilleret  CBuisseret  PDufier  JL The sensitive period for strabismic amblyopia in humans. Ophthalmology 1993;100 (3) 323- 327
PubMed
Fulton  ABMayer  DL Esotropic children with amblyopia: effects of patching on acuity. Graefes Arch Clin Exp Ophthalmol 1988;226 (4) 309- 312
PubMed
Mintz-Hittner  HAFernandez  KM Successful amblyopia therapy initiated after age 7 years: compliance cures. Arch Ophthalmol 2000;118 (11) 1535- 1541
PubMed
Stewart  CEMoseley  MJFielder  AR Defining and measuring treatment outcome in unilateral amblyopia. Br J Ophthalmol 2003;87 (10) 1229- 1231
PubMed
von Noorden  GKBinocular Vision and Ocular Motility: Theory and Management of Strabismus. 5th ed. St Louis, MO Mosby–Year Book1996;
Campbell  FWGreen  DG Monocular versus binocular visual acuity. Nature 1965;208 (5006) 191- 192
PubMed
Wiesel  TNHubel  DH Single-cell responses in striate cortex of kittens deprived of vision in one eye. J Neurophysiol 1963;261003- 1017
PubMed
Kiorpes  LKiper  DCO’Keefe  LPCavanaugh  JRMovshon  JA Neuronal correlates of amblyopia in the visual cortex of macaque monkeys with experimental strabismus and anisometropia. J Neurosci 1998;18 (16) 6411- 6424
PubMed
Movshon  JAEggers  HMGizzi  MSHendrickson  AEKiorpes  LBoothe  RG Effects of early unilateral blur on the macaque's visual system, III: physiological observations. J Neurosci 1987;7 (5) 1340- 1351
PubMed
Holopigian  KBlake  RGreenwald  MJ Selective losses in binocular vision in anisometropic amblyopes. Vision Res 1986;26 (4) 621- 630
PubMed
Baker  DHMeese  TSMansouri  BHess  RF Binocular summation of contrast remains intact in strabismic amblyopia. Invest Ophthalmol Vis Sci 2007;48 (11) 5332- 5338
PubMed
McKee  SPLevi  DMMovshon  JA The pattern of visual deficits in amblyopia. J Vis 2003;3 (5) 380- 405
PubMed
Lema  SABlake  R Binocular summation in normal and stereoblind humans. Vision Res 1977;17 (6) 691- 695
PubMed
Levi  DMHarwerth  RSManny  RE Suprathreshold spatial frequency detection and binocular interaction in strabismic and anisometropic amblyopia. Invest Ophthalmol Vis Sci 1979;18 (7) 714- 725
PubMed
Levi  DMHarwerth  RSSmith  EL Binocular interactions in normal and anomalous binocular vision. Doc Ophthalmol 1980;49 (2) 303- 324
PubMed
Pardhan  SGilchrist  J Binocular contrast summation and inhibition in amblyopia: the influence of the interocular difference on binocular contrast sensitivity. Doc Ophthalmol 1992;82 (3) 239- 248
PubMed
Hood  ASMorrison  JD The dependence of binocular contrast sensitivities on binocular single vision in normal and amblyopic human subjects. J Physiol 2002;540 (pt 2) 607- 622
PubMed
Kosslyn  SMFlynn  RAAmsterdam  JBWang  G Components of high-level vision: a cognitive neuroscience analysis and accounts of neurological syndromes. Cognition 1990;34 (3) 203- 277
PubMed
Vaina  LMGross  CG Perceptual deficits in patients with impaired recognition of biological motion after temporal lobe lesions. Proc Natl Acad Sci U S A 2004;101 (48) 16947- 16951
PubMed
Vaina  LMSoloviev  S First-order and second-order motion: neurological evidence for neuroanatomically distinct systems. Prog Brain Res 2004;144197- 212
PubMed
Levi  DM Visual processing in amblyopia: human studies. Strabismus 2006;14 (1) 11- 19
PubMed
Levi  DM Image segregation in strabismic amblyopia. Vision Res 2007;47 (13) 1833- 1838
PubMed
Grossberg  SPessoa  L Texture segregation, surface representation and figure-ground separation. Vision Res 1998;38 (17) 2657- 2684
PubMed
Popple  AVLevi  DM Amblyopes see true alignment where normal observers see illusory tilt. Proc Natl Acad Sci U S A 2000;97 (21) 11667- 11672
PubMed
Norcia  AMSampath  VHou  CPettet  MW Experience-expectant development of contour integration mechanisms in human visual cortex. J Vis 2005;5 (2) 116- 130
PubMed
Levi  DMKlein  SASharma  V Position jitter and undersampling in pattern perception. Vision Res 1999;39 (3) 445- 465
PubMed
Flom  MCWeymouth  FWKahneman  D Visual resolution and contour interaction. J Opt Soc Am 1963;531026- 1032
PubMed
Hess  RFJacobs  RJ A preliminary report of acuity and contour interactions across the amblyope's visual field. Vision Res 1979;19 (12) 1403- 1408
PubMed
Levi  DM Crowding: an essential bottleneck for object recognition: a mini-review. Vision Res 2008;48 (5) 635- 654
PubMed
May  KAHess  RF Ladder contours are undetectable in the periphery: a crowding effect? J Vis 2007;7 (13) 9.1- 9.15
PubMed10.1167/7.13.9
Bex  PJMareschal  IDakin  SC Contrast gain control in natural scenes. J Vis 2007;7 (11) 12.1- 12.12
PubMed10.1167/7.11.12
Elder  JHGoldberg  RM Ecological statistics of Gestalt laws for the perceptual organization of contours. J Vis 2002;2 (4) 324- 353
PubMed
Fei-Fei  LIyer  AKoch  CPerona  P What do we perceive in a glance of a real-world scene? J Vis 2007;7 (1) 10
PubMed10.1167/7.1.10
Fowlkes  CCMartin  DRMalik  J Local figure-ground cues are valid for natural images. J Vis 2007;7 (8) 2
PubMed10.1167/7.8.2
Geisler  WSPerry  JSSuper  BJGallogly  DP Edge co-occurrence in natural images predicts contour grouping performance. Vision Res 2001;41 (6) 711- 724
PubMed
Hansen  BCEssock  EA A horizontal bias in human visual processing of orientation and its correspondence to the structural components of natural scenes. J Vis 2004;4 (12) 1044- 1060
PubMed
Simoncelli  EPOlshausen  BA Natural image statistics and neural representation. Annu Rev Neurosci 2001;241193- 1216
PubMed
David  SVVinje  WEGallant  JL Natural stimulus statistics alter the receptive field structure of V1 neurons. J Neurosci 2004;24 (31) 6991- 7006
PubMed
Gilbert  CDWiesel  TN Columnar specificity of intrinsic horizontal and corticocortical connections in cat visual cortex. J Neurosci 1989;9 (7) 2432- 2442
PubMed
Kruger  N Collinearity and parallelism are statistically significant second-order relations of complex cell responses. Neural Process Lett 1998;8117- 129
Sigman  MCecchi  GAGilbert  CDMagnasco  MO On a common circle: natural scenes and Gestalt rules. Proc Natl Acad Sci U S A 2001;98 (4) 1935- 1940
PubMed
VanRullen  RKoch  C Competition and selection during visual processing of natural scenes and objects. J Vis 2003;3 (1) 75- 85
PubMed
Ramsden  BMHung  CPRoe  AW Real and illusory contour processing in area V1 of the primate: a cortical balancing act. Cereb Cortex 2001;11 (7) 648- 665
PubMed
Zhan  CABaker  CL  Jr Boundary cue invariance in cortical orientation maps. Cereb Cortex 2006;16 (6) 896- 906
PubMed
Grill-Spector  KKushnir  TEdelman  SItzchak  YMalach  R Cue-invariant activation in object-related areas of the human occipital lobe. Neuron 1998;21 (1) 191- 202
PubMed
Marcar  VLLoenneker  TStraessle  AJaggy  SKucian  KMartin  E An fMRI study of the cerebral macro network involved in “cue invariant” form perception and how it is influenced by stimulus complexity. Neuroimage 2004;23 (3) 947- 955
PubMed
Sáry  GVogels  ROrban  GA Cue-invariant shape selectivity of macaque inferior temporal neurons. Science 1993;260 (5110) 995- 997
PubMed
Vuilleumier  PHenson  RNDriver  JDolan  RJ Multiple levels of visual object constancy revealed by event-related fMRI of repetition priming. Nat Neurosci 2002;5 (5) 491- 499
PubMed
Thorpe  SFize  DMarlot  C Speed of processing in the human visual system. Nature 1996;381 (6582) 520- 522
PubMed
Potter  MC Meaning in visual search. Science 1975;187 (4180) 965- 966
PubMed
VanRullen  RThorpe  SJ Is it a bird? is it a plane? ultra-rapid visual categorisation of natural and artifactual objects. Perception 2001;30 (6) 655- 668
PubMed
Walther  DBCaddigan  EFei-Fei  LBeck  DM Natural scene categories revealed in distributed patterns of activity in the human brain. J Neurosci 2009;29 (34) 10573- 10581
PubMed
Peelen  MVFei-Fei  LKastner  S Neural mechanisms of rapid natural scene categorization in human visual cortex. Nature 2009;460 (7251) 94- 97
PubMed
Biederman  ICooper  EE Evidence for complete translational and reflectional invariance in visual object priming. Perception 1991;20 (5) 585- 593
PubMed
Bar  MBiederman  I Localizing the cortical region mediating visual awareness of object identity. Proc Natl Acad Sci U S A 1999;96 (4) 1790- 1793
PubMed
Yantis  S Multielement visual tracking: attention and perceptual organization. Cogn Psychol 1992;24 (3) 295- 340
PubMed
Luck  SJVogel  EK The capacity of visual working memory for features and conjunctions. Nature 1997;390 (6657) 279- 281
PubMed
Cowan  N The magical number 4 in short-term memory: a reconsideration of mental storage capacity. Behav Brain Sci 2001;24 (1) 87- 114
PubMed
Cortese  FGoltz  HCHirji  ZCheyne  DOWong  AM Brain mechanisms of vision in human amblyopia: a magnetoencephalography (MEG) study [abstract]. Neuroimage 2008;41 ((suppl 1)) S18010.1016/j.neuroimage.2008.04.008
Hirji  ZACortese  FGoltz  HCCheyne  DOWong  AM Neural correlates of pattern perception in human amblyopia: an MEG study [ARVO e-abstract D973]. Invest Ophthalmol Vis Sci 2009;504707
Grant  SMelmoth  DRMorgan  MJFinlay  AL Prehension deficits in amblyopia. Invest Ophthalmol Vis Sci 2007;48 (3) 1139- 1148
PubMed
Webber  ALWood  JMGole  GABrown  B The effect of amblyopia on fine motor skills in children. Invest Ophthalmol Vis Sci 2008;49 (2) 594- 603
PubMed
Niechwiej-Szwedo  EGoltz  HChandrakumar  MHirji  ZACrawford  JDWong  AM Effects of anisometropic amblyopia on visuomotor behaviour, II: visually-guided reaching [published online November 4, 2010]. Invest Ophthalmol Vis Sci
PubMed
Niechwiej-Szwedo  EGoltz  HChandrakumar  MHirji  ZAWong  AM Effects of anisometropic amblyopia on visuomotor behaviour, I: saccadic eye movements. Invest Ophthalmol Vis Sci 2010;51 (12) 6348- 6354
PubMed

Figures

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Figure 1.

A sample of images used in the match-to-sample task.

Graphic Jump Location
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Figure 2.

Each trial consisted of a reference image displayed on the right side of the screen subtending a visual angle of 8°. Simultaneously, on the left side of the screen, 4 choices were shown in a 2 × 2 array, each within a circular aperture that was 5° in diameter. One of these 4 choices was identical to the reference image, whereas the other 3 resembled the reference image but were not identical to it. In this particular trial shown, the choice at the lower left was identical to the reference image on the right, and an overall correct response rate of 57% was obtained across all participants.

Graphic Jump Location
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Figure 3.

Performance by viewing eye showing the mean rates of correct, incorrect, and no responses during viewing with amblyopic, fellow, and normal eyes. Error bars represent 1 SD.

Graphic Jump Location
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Figure 4.

Performance by treatment outcomes of the amblyopic eye showing the mean rates of correct, incorrect, and no responses in the unsuccessfully treated, successfully treated, and normal groups. Error bars represent 1 SD.

Graphic Jump Location

Tables

References

American Academy of Ophthalmology,Amblyopia: Preferred Practice Pattern. San Francisco, CA American Academy of Ophthalmology2007;
Brown  SAWeih  LMFu  CLDimitrov  PTaylor  HR McCarty  CA Prevalence of amblyopia and associated refractive errors in an adult population in Victoria, Australia. Ophthalmic Epidemiol 2000;7 (4) 249- 258
PubMed
Hillis  A Amblyopia: prevalent, curable, neglected. Public Health Rev 1986;14 (3-4) 213- 235
PubMed
Preslan  MWNovak  A Baltimore Vision Screening Project. Ophthalmology 1996;103 (1) 105- 109
PubMed
Krueger  DEEderer  FReport on the National Eye Institute's Visual Acuity Impairment Survey Pilot Study. Bethesda, MD Office of Biometry and Epidemiology, National Eye Institute1984;
Vinding  TGregersen  EJensen  ARindziunski  E Prevalence of amblyopia in old people without previous screening and treatment: an evaluation of the present prophylactic procedures among children in Denmark. Acta Ophthalmol (Copenh) 1991;69 (6) 796- 798
PubMed
Buch  HVinding  TLa Cour  MNielsen  NV The prevalence and causes of bilateral and unilateral blindness in an elderly urban Danish population: the Copenhagen City Eye Study. Acta Ophthalmol Scand 2001;79 (5) 441- 449
PubMed
Attebo  KMitchell  PCumming  RSmith  WJolly  NSparkes  R Prevalence and causes of amblyopia in an adult population. Ophthalmology 1998;105 (1) 154- 159
PubMed
Levi  DMHarwerth  RS Spatio-temporal interactions in anisometropic and strabismic amblyopia. Invest Ophthalmol Vis Sci 1977;16 (1) 90- 95
PubMed
Hess  RFHowell  ER The threshold contrast sensitivity function in strabismic amblyopia: evidence for a two type classification. Vision Res 1977;17 (9) 1049- 1055
PubMed
Levi  DMWaugh  SJBeard  BL Spatial scale shifts in amblyopia. Vision Res 1994;34 (24) 3315- 3333
PubMed
Simmers  AJLedgeway  THess  RF McGraw  PV Deficits to global motion processing in human amblyopia. Vision Res 2003;43 (6) 729- 738
PubMed
Simmers  AJBex  PJ The representation of global spatial structure in amblyopia. Vision Res 2004;44 (5) 523- 533
PubMed
Simmers  AJLedgeway  THess  RF The influences of visibility and anomalous integration processes on the perception of global spatial form versus motion in human amblyopia. Vision Res 2005;45 (4) 449- 460
PubMed
Mansouri  BHess  RF The global processing deficit in amblyopia involves noise segregation. Vision Res 2006;46 (24) 4104- 4117
PubMed
Levi  DMYu  CKuai  SGRislove  E Global contour processing in amblyopia. Vision Res 2007;47 (4) 512- 524
PubMed
Hess  RF McIlhagga  WField  DJ Contour integration in strabismic amblyopia: the sufficiency of an explanation based on positional uncertainty. Vision Res 1997;37 (22) 3145- 3161
PubMed
Chandna  APennefather  PMKovács  INorcia  AM Contour integration deficits in anisometropic amblyopia. Invest Ophthalmol Vis Sci 2001;42 (3) 875- 878
PubMed
Wong  EHLevi  DM McGraw  PV Is second-order spatial loss in amblyopia explained by the loss of first-order spatial input? Vision Res 2001;41 (23) 2951- 2960
PubMed
Wong  EHLevi  DM Second-order spatial summation in amblyopia. Vision Res 2005;45 (21) 2799- 2809
PubMed
Mansouri  BAllen  HAHess  RF Detection, discrimination and integration of second-order orientation information in strabismic and anisometropic amblyopia. Vision Res 2005;45 (18) 2449- 2460
PubMed
Levi  DMSaarinen  J Perception of mirror symmetry in amblyopic vision. Vision Res 2004;44 (21) 2475- 2482
PubMed
Simmers  AJLedgeway  TMansouri  BHutchinson  CVHess  RF The extent of the dorsal extra-striate deficit in amblyopia. Vision Res 2006;46 (16) 2571- 2580
PubMed
Sharma  VLevi  DMKlein  SA Undercounting features and missing features: evidence for a high-level deficit in strabismic amblyopia. Nat Neurosci 2000;3 (5) 496- 501
PubMed
Asper  LJCrewther  DPCrewther  S Do different amblyopes have different attentional blinks [ARVO abstract]? Invest Ophthalmol Vis Sci 1 May2003;44S4094
Ho  CSPaul  PSAsirvatham  ACavanagh  PCline  RGiaschi  DE Abnormal spatial selection and tracking in children with amblyopia. Vision Res 2006;46 (19) 3274- 3283
PubMed
Leguire  LERogers  GLBremer  DL Amblyopia: the normal eye is not normal. J Pediatr Ophthalmol Strabismus 1990;27 (1) 32- 39
PubMed
Levi  DMKlein  SA Vernier acuity, crowding and amblyopia. Vision Res 1985;25 (7) 979- 991
PubMed
Cox  JFSuh  SLeguire  LE Vernier acuity in amblyopic and nonamblyopic children. J Pediatr Ophthalmol Strabismus 1996;33 (1) 39- 46
PubMed
Bedell  HEFlom  MCBarbeito  R Spatial aberrations and acuity in strabismus and amblyopia. Invest Ophthalmol Vis Sci 1985;26 (7) 909- 916
PubMed
Kovács  IPolat  UPennefather  PMChandna  ANorcia  AM A new test of contour integration deficits in patients with a history of disrupted binocular experience during visual development. Vision Res 2000;40 (13) 1775- 1783
PubMed
Chandna  AGonzalez-Martin  JANorcia  AM Recovery of contour integration in relation to logMAR visual acuity during treatment of amblyopia in children. Invest Ophthalmol Vis Sci 2004;45 (11) 4016- 4022
PubMed
Giaschi  DERegan  DKraft  SPHong  XH Defective processing of motion-defined form in the fellow eye of patients with unilateral amblyopia. Invest Ophthalmol Vis Sci 1992;33 (8) 2483- 2489
PubMed
Kelly  SLBuckingham  TJ Movement hyperacuity in childhood amblyopia. Br J Ophthalmol 1998;82 (9) 991- 995
PubMed
Hess  RFDemanins  R Contour integration in anisometropic amblyopia. Vision Res 1998;38 (6) 889- 894
PubMed
Ho  CSGiaschi  DE Stereopsis-dependent deficits in maximum motion displacement in strabismic and anisometropic amblyopia. Vision Res 2007;47 (21) 2778- 2785
PubMed
Levi  DMKlein  SAYap  YL Positional uncertainty in peripheral and amblyopic vision. Vision Res 1987;27 (4) 581- 597
PubMed
Pediatric Eye Disease Investigator Group, A randomized trial of atropine vs patching for treatment of moderate amblyopia in children. Arch Ophthalmol 2002;120 (3) 268- 278
PubMed
Hiscox  FStrong  NThompson  JRMinshull  CWoodruff  G Occlusion for amblyopia: a comprehensive survey of outcome. Eye (Lond) 1992;6 (pt 3) 300- 304
PubMed
Latvala  MLPaloheimo  MKarma  A Screening of amblyopic children and long-term follow-up. Acta Ophthalmol Scand 1996;74 (5) 488- 492
PubMed
Flynn  JTCassady  JC Current trends in amblyopia therapy. Ophthalmology 1978;85 (5) 428- 450
PubMed
Kutschke  PJScott  WEKeech  RV Anisometropic amblyopia. Ophthalmology 1991;98 (2) 258- 263
PubMed
Robinson  J Simple anisometropia and amblyopia. Br Orthopt J 1961;1813- 26
Lithander  JSjöstrand  J Anisometropic and strabismic amblyopia in the age group 2 years and above: a prospective study of the results of treatment. Br J Ophthalmol 1991;75 (2) 111- 116
PubMed
Epelbaum  MMilleret  CBuisseret  PDufier  JL The sensitive period for strabismic amblyopia in humans. Ophthalmology 1993;100 (3) 323- 327
PubMed
Fulton  ABMayer  DL Esotropic children with amblyopia: effects of patching on acuity. Graefes Arch Clin Exp Ophthalmol 1988;226 (4) 309- 312
PubMed
Mintz-Hittner  HAFernandez  KM Successful amblyopia therapy initiated after age 7 years: compliance cures. Arch Ophthalmol 2000;118 (11) 1535- 1541
PubMed
Stewart  CEMoseley  MJFielder  AR Defining and measuring treatment outcome in unilateral amblyopia. Br J Ophthalmol 2003;87 (10) 1229- 1231
PubMed
von Noorden  GKBinocular Vision and Ocular Motility: Theory and Management of Strabismus. 5th ed. St Louis, MO Mosby–Year Book1996;
Campbell  FWGreen  DG Monocular versus binocular visual acuity. Nature 1965;208 (5006) 191- 192
PubMed
Wiesel  TNHubel  DH Single-cell responses in striate cortex of kittens deprived of vision in one eye. J Neurophysiol 1963;261003- 1017
PubMed
Kiorpes  LKiper  DCO’Keefe  LPCavanaugh  JRMovshon  JA Neuronal correlates of amblyopia in the visual cortex of macaque monkeys with experimental strabismus and anisometropia. J Neurosci 1998;18 (16) 6411- 6424
PubMed
Movshon  JAEggers  HMGizzi  MSHendrickson  AEKiorpes  LBoothe  RG Effects of early unilateral blur on the macaque's visual system, III: physiological observations. J Neurosci 1987;7 (5) 1340- 1351
PubMed
Holopigian  KBlake  RGreenwald  MJ Selective losses in binocular vision in anisometropic amblyopes. Vision Res 1986;26 (4) 621- 630
PubMed
Baker  DHMeese  TSMansouri  BHess  RF Binocular summation of contrast remains intact in strabismic amblyopia. Invest Ophthalmol Vis Sci 2007;48 (11) 5332- 5338
PubMed
McKee  SPLevi  DMMovshon  JA The pattern of visual deficits in amblyopia. J Vis 2003;3 (5) 380- 405
PubMed
Lema  SABlake  R Binocular summation in normal and stereoblind humans. Vision Res 1977;17 (6) 691- 695
PubMed
Levi  DMHarwerth  RSManny  RE Suprathreshold spatial frequency detection and binocular interaction in strabismic and anisometropic amblyopia. Invest Ophthalmol Vis Sci 1979;18 (7) 714- 725
PubMed
Levi  DMHarwerth  RSSmith  EL Binocular interactions in normal and anomalous binocular vision. Doc Ophthalmol 1980;49 (2) 303- 324
PubMed
Pardhan  SGilchrist  J Binocular contrast summation and inhibition in amblyopia: the influence of the interocular difference on binocular contrast sensitivity. Doc Ophthalmol 1992;82 (3) 239- 248
PubMed
Hood  ASMorrison  JD The dependence of binocular contrast sensitivities on binocular single vision in normal and amblyopic human subjects. J Physiol 2002;540 (pt 2) 607- 622
PubMed
Kosslyn  SMFlynn  RAAmsterdam  JBWang  G Components of high-level vision: a cognitive neuroscience analysis and accounts of neurological syndromes. Cognition 1990;34 (3) 203- 277
PubMed
Vaina  LMGross  CG Perceptual deficits in patients with impaired recognition of biological motion after temporal lobe lesions. Proc Natl Acad Sci U S A 2004;101 (48) 16947- 16951
PubMed
Vaina  LMSoloviev  S First-order and second-order motion: neurological evidence for neuroanatomically distinct systems. Prog Brain Res 2004;144197- 212
PubMed
Levi  DM Visual processing in amblyopia: human studies. Strabismus 2006;14 (1) 11- 19
PubMed
Levi  DM Image segregation in strabismic amblyopia. Vision Res 2007;47 (13) 1833- 1838
PubMed
Grossberg  SPessoa  L Texture segregation, surface representation and figure-ground separation. Vision Res 1998;38 (17) 2657- 2684
PubMed
Popple  AVLevi  DM Amblyopes see true alignment where normal observers see illusory tilt. Proc Natl Acad Sci U S A 2000;97 (21) 11667- 11672
PubMed
Norcia  AMSampath  VHou  CPettet  MW Experience-expectant development of contour integration mechanisms in human visual cortex. J Vis 2005;5 (2) 116- 130
PubMed
Levi  DMKlein  SASharma  V Position jitter and undersampling in pattern perception. Vision Res 1999;39 (3) 445- 465
PubMed
Flom  MCWeymouth  FWKahneman  D Visual resolution and contour interaction. J Opt Soc Am 1963;531026- 1032
PubMed
Hess  RFJacobs  RJ A preliminary report of acuity and contour interactions across the amblyope's visual field. Vision Res 1979;19 (12) 1403- 1408
PubMed
Levi  DM Crowding: an essential bottleneck for object recognition: a mini-review. Vision Res 2008;48 (5) 635- 654
PubMed
May  KAHess  RF Ladder contours are undetectable in the periphery: a crowding effect? J Vis 2007;7 (13) 9.1- 9.15
PubMed10.1167/7.13.9
Bex  PJMareschal  IDakin  SC Contrast gain control in natural scenes. J Vis 2007;7 (11) 12.1- 12.12
PubMed10.1167/7.11.12
Elder  JHGoldberg  RM Ecological statistics of Gestalt laws for the perceptual organization of contours. J Vis 2002;2 (4) 324- 353
PubMed
Fei-Fei  LIyer  AKoch  CPerona  P What do we perceive in a glance of a real-world scene? J Vis 2007;7 (1) 10
PubMed10.1167/7.1.10
Fowlkes  CCMartin  DRMalik  J Local figure-ground cues are valid for natural images. J Vis 2007;7 (8) 2
PubMed10.1167/7.8.2
Geisler  WSPerry  JSSuper  BJGallogly  DP Edge co-occurrence in natural images predicts contour grouping performance. Vision Res 2001;41 (6) 711- 724
PubMed
Hansen  BCEssock  EA A horizontal bias in human visual processing of orientation and its correspondence to the structural components of natural scenes. J Vis 2004;4 (12) 1044- 1060
PubMed
Simoncelli  EPOlshausen  BA Natural image statistics and neural representation. Annu Rev Neurosci 2001;241193- 1216
PubMed
David  SVVinje  WEGallant  JL Natural stimulus statistics alter the receptive field structure of V1 neurons. J Neurosci 2004;24 (31) 6991- 7006
PubMed
Gilbert  CDWiesel  TN Columnar specificity of intrinsic horizontal and corticocortical connections in cat visual cortex. J Neurosci 1989;9 (7) 2432- 2442
PubMed
Kruger  N Collinearity and parallelism are statistically significant second-order relations of complex cell responses. Neural Process Lett 1998;8117- 129
Sigman  MCecchi  GAGilbert  CDMagnasco  MO On a common circle: natural scenes and Gestalt rules. Proc Natl Acad Sci U S A 2001;98 (4) 1935- 1940
PubMed
VanRullen  RKoch  C Competition and selection during visual processing of natural scenes and objects. J Vis 2003;3 (1) 75- 85
PubMed
Ramsden  BMHung  CPRoe  AW Real and illusory contour processing in area V1 of the primate: a cortical balancing act. Cereb Cortex 2001;11 (7) 648- 665
PubMed
Zhan  CABaker  CL  Jr Boundary cue invariance in cortical orientation maps. Cereb Cortex 2006;16 (6) 896- 906
PubMed
Grill-Spector  KKushnir  TEdelman  SItzchak  YMalach  R Cue-invariant activation in object-related areas of the human occipital lobe. Neuron 1998;21 (1) 191- 202
PubMed
Marcar  VLLoenneker  TStraessle  AJaggy  SKucian  KMartin  E An fMRI study of the cerebral macro network involved in “cue invariant” form perception and how it is influenced by stimulus complexity. Neuroimage 2004;23 (3) 947- 955
PubMed
Sáry  GVogels  ROrban  GA Cue-invariant shape selectivity of macaque inferior temporal neurons. Science 1993;260 (5110) 995- 997
PubMed
Vuilleumier  PHenson  RNDriver  JDolan  RJ Multiple levels of visual object constancy revealed by event-related fMRI of repetition priming. Nat Neurosci 2002;5 (5) 491- 499
PubMed
Thorpe  SFize  DMarlot  C Speed of processing in the human visual system. Nature 1996;381 (6582) 520- 522
PubMed
Potter  MC Meaning in visual search. Science 1975;187 (4180) 965- 966
PubMed
VanRullen  RThorpe  SJ Is it a bird? is it a plane? ultra-rapid visual categorisation of natural and artifactual objects. Perception 2001;30 (6) 655- 668
PubMed
Walther  DBCaddigan  EFei-Fei  LBeck  DM Natural scene categories revealed in distributed patterns of activity in the human brain. J Neurosci 2009;29 (34) 10573- 10581
PubMed
Peelen  MVFei-Fei  LKastner  S Neural mechanisms of rapid natural scene categorization in human visual cortex. Nature 2009;460 (7251) 94- 97
PubMed
Biederman  ICooper  EE Evidence for complete translational and reflectional invariance in visual object priming. Perception 1991;20 (5) 585- 593
PubMed
Bar  MBiederman  I Localizing the cortical region mediating visual awareness of object identity. Proc Natl Acad Sci U S A 1999;96 (4) 1790- 1793
PubMed
Yantis  S Multielement visual tracking: attention and perceptual organization. Cogn Psychol 1992;24 (3) 295- 340
PubMed
Luck  SJVogel  EK The capacity of visual working memory for features and conjunctions. Nature 1997;390 (6657) 279- 281
PubMed
Cowan  N The magical number 4 in short-term memory: a reconsideration of mental storage capacity. Behav Brain Sci 2001;24 (1) 87- 114
PubMed
Cortese  FGoltz  HCHirji  ZCheyne  DOWong  AM Brain mechanisms of vision in human amblyopia: a magnetoencephalography (MEG) study [abstract]. Neuroimage 2008;41 ((suppl 1)) S18010.1016/j.neuroimage.2008.04.008
Hirji  ZACortese  FGoltz  HCCheyne  DOWong  AM Neural correlates of pattern perception in human amblyopia: an MEG study [ARVO e-abstract D973]. Invest Ophthalmol Vis Sci 2009;504707
Grant  SMelmoth  DRMorgan  MJFinlay  AL Prehension deficits in amblyopia. Invest Ophthalmol Vis Sci 2007;48 (3) 1139- 1148
PubMed
Webber  ALWood  JMGole  GABrown  B The effect of amblyopia on fine motor skills in children. Invest Ophthalmol Vis Sci 2008;49 (2) 594- 603
PubMed
Niechwiej-Szwedo  EGoltz  HChandrakumar  MHirji  ZACrawford  JDWong  AM Effects of anisometropic amblyopia on visuomotor behaviour, II: visually-guided reaching [published online November 4, 2010]. Invest Ophthalmol Vis Sci
PubMed
Niechwiej-Szwedo  EGoltz  HChandrakumar  MHirji  ZAWong  AM Effects of anisometropic amblyopia on visuomotor behaviour, I: saccadic eye movements. Invest Ophthalmol Vis Sci 2010;51 (12) 6348- 6354
PubMed

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