Altered white matter in early visual pathways of humans with amblyopia

Allen, Brian; Spiegel, D.; Thompson, Benjamin; Pestilli, Franco; Rokers, Bas

doi:10.1016/j.visres.2014.12.021

Cited by 62 publications

(68 citation statements)

References 66 publications

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“…4,7,8 The magnitude of the increase in mean diffusivity of the optic radiation was roughly consistent with our previous study (about 10% greater compared to controls). We previously suggested this finding provides cursory evidence of a feedback, rather than feedforward, model of cortical abnormality in amblyopia.…”

Section: Thalamocortical and Corticocortical White Matter In Amblyopiasupporting

confidence: 91%

“…V1 and hMTþ were identified using the automatic cortical segmentation toolbox in the open source FreeSurfer software package. [24][25][26] Fiber Tracking and Cleaning Fiber tracking and cleaning was conducted in a protocol identical to that described by Allen et al 7 To summarize, tissue orientation was estimated in each voxel using constrained spherical deconvolution (CSD; lmax ¼ 6), and the white matter connections between specified ROI pairs were estimated using probabilistic tractography. In addition to the automatic cleaning step, each participant's optic nerve and optic tract estimates were overlaid on an anatomical T1 and manually pruned by an experienced neuroanatomist to ensure the fiber estimates were contained within the ground-truth anatomy.…”

Section: Data Preprocessingmentioning

confidence: 99%

“…[4][5][6] Visual white matter is also abnormal in amblyopia, particularly in fascicles connecting the thalamus to the visual (striate and extrastriate) cortex, such as the optic radiation. 7,8 These structural abnormalities appear to have downstream consequences, affecting not only the way visual information is processed in the cortex but also how that information is integrated in thalamocortical feedback networks. These abnormalities can vary by etiology and sometimes scale with the degree of perceptual loss, although these relationships are not always clear.…”

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confidence: 99%

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Retinothalamic White Matter Abnormalities in Amblyopia

Allen

Schmitt

Kushner

et al. 2018

Invest. Ophthalmol. Vis. Sci.

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PURPOSE. Amblyopia is associated with a broad array of perceptual and neural abnormalities in the visual system, particularly in untreated or unsuccessfully treated populations. Traditionally, it has been believed that the neural abnormalities are confined to the visual cortex and subcortex (e.g., lateral geniculate nucleus). Here, we investigate the presence of neuroanatomical abnormalities earlier in the visual stream, in the optic nerves and tracts, of participants with two predominant forms of amblyopia.METHODS. We used diffusion magnetic resonance imaging and probabilistic tractography to compare the microstructural properties of five white matter visual pathways between 15 participants with amblyopia (eight anisometropic, five strabismic, and two exhibiting both etiologies), and 13 age-matched controls.RESULTS. Participants with amblyopia exhibited significantly smaller mean fractional anisotropy in the optic nerve and optic tract (0.26 and 0.31 vs. 0.31 and 0.36 in controls, respectively). We also found greater mean diffusivity in the optic radiation compared to controls (0.72 lm 2 /s vs. 0.68 lm 2 /s, respectively). Comparing etiologies, the abnormalities in the precortical pathways tended to be more severe in participants with anisometropic compared to strabismic amblyopia, and anisometropic participants' optic nerves, optic tracts, and optic radiations significantly differed from control participants' (all, P < 0.05). CONCLUSIONS.The results indicate that amblyopia may be associated with microstructural abnormalities in neural networks as early as the retina, and these abnormalities may differ between amblyopic etiologies.

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Section: Thalamocortical and Corticocortical White Matter In Amblyopiasupporting

confidence: 91%

Section: Data Preprocessingmentioning

confidence: 99%

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confidence: 99%

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Retinothalamic White Matter Abnormalities in Amblyopia

Allen

Schmitt

Kushner

et al. 2018

Invest. Ophthalmol. Vis. Sci.

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“…12 In addition to changes in neural responses, structural neuroimaging has helped us understand the biological underpinnings of the behavioral differences in terms of changes in the structure of either grey matter [13][14][15][16][17][18][19] or white matter. [19][20][21][22][23] Grey matter contains cell bodies and is where neural computations take place. Structural changes in grey matter have been quantified via voxel-based morphometry (VBM), a technique that quantifies differences in brain shape between patients and controls.…”

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confidence: 99%

The Structural Properties of Major White Matter Tracts in Strabismic Amblyopia

Duan

Norcia

Yeatman

et al. 2015

Invest. Ophthalmol. Vis. Sci.

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PURPOSE. In order to better understand whether white matter structural deficits are present in strabismic amblyopia, we performed a survey of the tissue properties of 28 major white matter tracts using diffusion and quantitative magnetic resonance imaging approaches.METHODS. We used diffusion-based tensor modeling and a new quantitative T1 protocol to measure fractional anisotropy (FA), mean diffusivity (MD), and myelin-sensitive T1 values. We surveyed tracts in the occipital lobe, including the vertical occipital fasciculus (VOF)-a newly rediscovered tract that bridges dorsal and ventral areas of the occipital lobe, as well as tracts across the rest of the brain. RESULTS.Adults with long-standing strabismic amblyopia show tract-specific elevations in MD. We rank-ordered the tracts on the basis of their MD effect-size. The four most affected tracts were the anterior frontal corpus callosum (ACC), the right VOF, the left inferior longitudinal fasciculus (ILF) and the left optic radiation. CONCLUSIONS.The results suggest that most white matter tissue properties are relatively robust to the early visual insult caused by strabismus. However, strabismic amblyopia does affect MD, not only in occipital tracts, such as the VOF and optic radiation, but also in long range association tracts connecting visual cortex to the frontal and temporal lobes (ILF) and connecting the two hemispheres (ACC).

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“…Such poor correlation may be due to a chronically blurred image in one eye (anisometropia), a turned eye (strabismus), or deprivation of one or both eyes (1) . In anisometropic amblyopia, the connections between the retina and cortex do not form an accurate cortical topographic map, as in a normal subject, which results in widespread visual loss in the affected eye (2)(3)(4) .…”

Section: Introductionmentioning

confidence: 99%

Dysfunction in the fellow eyes of strabismic and anisometropic amblyopic children assessed by visually evoked potentials

Andrade¹,

Berezovsky²,

Sacai³

et al. 2016

Arquivos Brasileiros De Oftalmologia

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Approved by the following research ethics committee: Federal University of São Paulo (approval n o 0503/08). ABSTRACTPurpose: To evaluate visual acuity and transient pattern reversal (PR) visual evoked potentials (VEPs) in the fellow eyes of children with strabismic and/or anisometropic amblyopia. Methods: Children diagnosed with strabismic and/or anisometropic amblyopia were recruited for electrophysiological assessment by VEPs. Monocular grating and optotype acuity were measured using sweep-VEPs and an Early Treatment Diabetic Retinopathy Study chart, respectively. During the same visit, transient PR-VEPs of each eye were recorded using stimuli subtending with a visual angle of 60' , 15' , and 7.5' . Parameters of amplitude (in μV) and latency (in ms) were determined from VEP recordings. Results: A group of 40 strabismic and/or anisometropic amblyopic children (22 females: 55%, mean age= 8.7 ± 2.2 years, median= 8 years) was examined. A control group of 19 healthy children (13 females: 68.4%, mean age= 8.2 ± 2.6 years, median= 8 years) was also included. The fellow eyes of all amblyopes had significantly worse optotype acuity (p=0.021) than the control group, regardless of whether they were strabismic (p=0.040) or anisometropic (p=0.048). Overall, grating acuity was significantly worse in the fellow eyes of amblyopes (p=0.016) than in healthy controls. Statistically prolonged latency for visual angles of 15' and 7.5' (p=0.018 and 0.002, respectively) was found in the strabismic group when compared with the control group. For the smaller visual stimulus (7.5'), statistically prolonged latency was found among all fellow eyes of amblyopic children (p<0.001). Conclusions:The fellow eyes of amblyopic children showed worse optotype and grating acuity, with subtle abnormalities in the PR-VEP detected as prolonged latencies for smaller size stimuli when compared with eyes of healthy children. These findings show the deleterious effects of amblyopia in several distinct visual functions, mainly those related to spatial vision. Keywords

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Altered white matter in early visual pathways of humans with amblyopia

Cited by 62 publications

References 66 publications

Retinothalamic White Matter Abnormalities in Amblyopia

Retinothalamic White Matter Abnormalities in Amblyopia

The Structural Properties of Major White Matter Tracts in Strabismic Amblyopia

Dysfunction in the fellow eyes of strabismic and anisometropic amblyopic children assessed by visually evoked potentials

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