Amblyopia

Campos, Emilio C.

doi:10.1016/s0039-6257(95)80044-1

Cited by 99 publications

(72 citation statements)

References 99 publications

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“…A treatment that shares some common theoretical basis with the present treatment is the CAM stimulator (40)(41)(42). This instrument, used to be applied in conjunction with occlusion in children, is a rotating disk with black and white stripes aimed at exposing the visual cortex to various spatial frequencies.…”

Section: Discussionmentioning

confidence: 99%

Improving vision in adult amblyopia by perceptual learning

Polat

Ma-Naim

Belkin

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

379

385

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Practicing certain visual tasks leads, as a result of a process termed ''perceptual learning,'' to a significant improvement in performance. Learning is specific for basic stimulus features such as local orientation, retinal location, and eye of presentation, suggesting modification of neuronal processes at the primary visual cortex in adults. It is not known, however, whether such low-level learning affects higher-level visual tasks such as recognition. By systematic low-level training of an adult visual system malfunctioning as a result of abnormal development (leading to amblyopia) of the primary visual cortex during the ''critical period,'' we show here that induction of low-level changes might yield significant perceptual benefits that transfer to higher visual tasks. The training procedure resulted in a 2-fold improvement in contrast sensitivity and in letter-recognition tasks. These findings demonstrate that perceptual learning can improve basic representations within an adult visual system that did not develop during the critical period.A mblyopia is characterized by several functional abnormalities in spatial vision (for reviews see refs. 1-4), including reductions in visual acuity (VA), contrast-sensitivity function (CSF), and vernier acuity as well as spatial distortion (5), abnormal spatial interactions (6, 7), and impaired contour detection (8,9). In addition, amblyopic individuals suffer from binocular abnormalities such as impaired stereoacuity and abnormal binocular summation. The visual deficiencies are thought to be irreversible after the first decade of life (10-12), by which time the developmental maturation window has been terminated. The loss of vision is thought to result from abnormal operation of the neuronal network within the primary visual cortex, particularly of orientation-selective neurons and their interactions (13). The perceptual learning procedure described in this study was designed to train this network by efficiently stimulating these neuronal populations and effectively promoting their spatial interactions.Spatial interactions in human vision can be probed by contrast detection of a localized target in the presence of flankers (Fig. 1). These experiments show that the contrast threshold of a foveal Gabor signal (GS) is reduced in the presence of cooriented and coaligned (collinear) high-contrast GS flankers (14-18). The excitatory interaction is range-dependent and is maximal for target-flanker separation of approximately three times the GS wavelength. Smaller separations can raise the target threshold, depending on flanker contrast and phase (19). Singleunit recordings suggest that the underlying mechanisms reside within the primary visual cortex (20,21). Neuronal responses in the visual cortex are tuned for location, orientation, and spatial frequency. Recent evidence from studies in the cat and the monkey (20,(22)(23)(24)(25) shows that neuronal responses in the primary visual cortex are modulated by remote image parts, with both excitatory and inhibitory effects observ...

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Section: Discussionmentioning

confidence: 99%

Improving vision in adult amblyopia by perceptual learning

Polat

Ma-Naim

Belkin

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

379

385

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“…New indications for botulinum toxin treatment are being explored, and its use in e.g. the early treatment of infantile esotropia is under study (McNeer et al 1994;Campos 1995).…”

Section: Discussionmentioning

confidence: 99%

“…Although all types of strabismus in children have been successfully treated with botulinum toxin (Magoon 1984;Scott et al 1990;Ing 1993;McNeer et al 1994;Campos 1995), it has not been used in children in Scandinavia, except in a few very special cases.…”

mentioning

confidence: 99%

Treatment of strabismus and nystagmus with botulinum toxin type A, An evaluation of effects and complications

Lennerstrand

Nordbø

Tian

et al. 1998

Acta Ophthalmologica Scandinavica

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ABSTRACT.Purpose: Injection of botulinum toxin type A into eye muscles leads to a temporary paralysis and the effects have been evaluated in strabismus or nystagmus. Method: A total of 112 patients with different types of concomitant and paralytic strabismus and acquired nystagmus were treated with botulinum toxin, according to well-established indications. Results: The lasting effects of the injections on strabismic angle were largest in esotropia, consecutive exotropia and abducens palsy, and amounted to, on an average, 12 prism diopters or 6 degrees. The larger the strabismus the better was the effect. Repeated injections reduced the angle further. In complex nystagmus forms retrobulbar injections could be used. The side effects were mostly due to spread of botulinum toxin to the levator, producing ptosis (8%), or the inferior rectus muscle, causing vertical strabismus (10%). On an average 42% of the patients were later operated for strabismus and nystagmus. Conclusion: Injection of botulinum toxin A into eye muscles is a valuable adjunct to surgery in the treatment of strabismus and nystagmus.

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“…Pattern visual evoked potential (PVEP) test results of human eyes with amblypia showed attenuated amplitudes and prolonged latencies in studies. [1][2][3] Although the loss of visual acuity in amblyopia is considered to be cortical in origin, it remains unclear whether the retina is also affected in patients with amblyopia. [4][5][6][7][8] Functionally, suppression of eye with amblyopia causes loss of binocular neuron function in the visual cortex [9,10].…”

Section: Introductionmentioning

confidence: 99%

Electrophysiologic evaluation of amblyopia

Hamurcu¹,

Çelik²,

Saricaoğlu³

et al. 2017

Eye Care Vis

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Purpose: To compare amblyopic eyes and other eyes of the unilaterally amblyopic patients in the terms of pattern visual evoked potentials (pVEP), pattern electroretinogram (pERG) and flash electroretinogram(fERG) tests. Methods:This study was performed at Ankara Numune Training and Research Hospital between November-2015 and August-2016. Forty-one patients above the age of 15 with anisometropic amblyopia were evaluated for their amblyopic and other eyes. The patients were tested by Metrovision brand monpack model visual electrophysiology device for pVEP, fERG and pERG tests. Mean latance and amplitudes were examined statistically.Results: A statistically significant difference was found in decrease of P100 amplitude (p<0.05) and increase of P100 latency (p<0.01) of amblyopic eyes in all 5 patterns pVEP recorded. In pERG results P50 and N95 wave amplitudes were decreased in amblyopic eyes (p<0.01) but there was no statistical difference in latency period between amblyopic eyes and other eyes (p>0.05). In fERG results, rod response b wave amplitudes was lower and latency was increased in amblyopic eyes (p<0.01). However cone responses were no statistical difference in amblyopic and other eyes (p>0.05). Conclusion:According to our results, amblyopia is not only a cortical pathology. Also cortico-retinal pathologies that can not be detected by routine opthalmologic examination may accompany amblyopia. pERG, fERG and pVEP are objective methods for diagnosis and follow up of amblyopic patients and valuable guides for clinicians.

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Amblyopia

Cited by 99 publications

References 99 publications

Improving vision in adult amblyopia by perceptual learning

Improving vision in adult amblyopia by perceptual learning

Treatment of strabismus and nystagmus with botulinum toxin type A, An evaluation of effects and complications

Electrophysiologic evaluation of amblyopia

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