Problems of Organic Lesions in Functional Amblyopia

Sachsenweger, R

doi:10.1159/000390816

Cited by 10 publications

(8 citation statements)

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“…Amblyopia has been found to be the first, second, or third leading cause of visual impairment in adults of various age distributions (Sachsenweger, 1968; National Eye Institute. Office of & Epidemiology, 1984; Klein et al, 1995; Attebo et al, 1996; Robaei et al, 2005; Robaei et al, 2006; Gilbert et al, 2008).…”

Section: Prevalencementioning

confidence: 99%

The relationship between anisometropia and amblyopia

Barrett

Bradley

Candy

2013

Progress in Retinal and Eye Research

139

121

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This review aims to disentangle cause and effect in the relationship between anisometropia and amblyopia. Specifically, we examine the literature for evidence to support different possible developmental sequences that could ultimately lead to the presentation of both conditions. The prevalence of anisometropia is around 20% for an inter-ocular difference of 0.5D or greater in spherical equivalent refraction, falling to 2-3%, for an inter-ocular difference of 3D or above. Anisometropia prevalence is relatively high in the weeks following birth, in the teenage years coinciding with the onset of myopia and, most notably, in older adults starting after the onset of presbyopia. It has about one-third the prevalence of bilateral refractive errors of the same magnitude. Importantly, the prevalence of anisometropia is higher in highly ametropic groups, suggesting that emmetropization failures underlying ametropia and anisometropia may be similar. Amblyopia is present in 1-3% of humans and around one-half to two-thirds of amblyopes have anisometropia either alone or in combination with strabismus. The frequent co-existence of amblyopia and anisometropia at a child’s first clinical examination promotes the belief that the anisometropia has caused the amblyopia, as has been demonstrated in animal models of the condition. In reviewing the human and monkey literature however it is clear that there are additional paths beyond this classic hypothesis to the co-occurrence of anisometropia and amblyopia. For example, after amblyopia secondary to either deprivation or strabismus has emerged, anisometropia often follows. In cases of anisometropia with no apparent deprivation or strabismus, questions remain about the failure of the emmetropization mechanism that routinely eliminates infantile anisometropia. Also, the chronology of amblyopia development is poorly documented in cases of ‘pure’ anisometropic amblyopia. Although indirect, the therapeutic impact of refractive correction on anisometropic amblyopia provides strong support for the hypothesis that the anisometropia caused the amblyopia. Direct evidence for the aetiology of anisometropic amblyopia will require longitudinal tracking of at-risk infants, which poses numerous methodological challenges. However, if we are to prevent this condition, we must understand the factors that cause it to develop.

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Section: Prevalencementioning

confidence: 99%

The relationship between anisometropia and amblyopia

Barrett

Bradley

Candy

2013

Progress in Retinal and Eye Research

139

121

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“…Amblyopia is clinically important because it is the most frequent cause of vision loss in infants and young children (Sachsenweger, 1968) aside from refractive error. Amblyopia is also of basic interest because it reflects the neural impairments that occur when normal visual development is disrupted, providing an ideal model for understanding when and how brain plasticity may be harnessed for recovery of function.…”

Section: Introductionmentioning

confidence: 99%

Stereopsis and amblyopia: A mini-review

2015

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Amblyopia is a neuro-developmental disorder of the visual cortex that arises from abnormal visual experience early in life. Amblyopia is clinically important because it is a major cause of vision loss in infants and young children. Amblyopia is also of basic interest because it reflects the neural impairment that occurs when normal visual development is disrupted. Amblyopia provides an ideal model for understanding when and how brain plasticity may be harnessed for recovery of function. Over the past two decades there has been a rekindling of interest in developing more effective methods for treating amblyopia, and for extending the treatment beyond the critical period, as exemplified by new clinical trials and new basic research studies. The focus of this review is on stereopsis and its potential for recovery. Impaired stereoscopic depth perception is the most common deficit associated with amblyopia under ordinary (binocular) viewing conditions (Webber & Wood, 2005). Our review of the extant literature suggests that this impairment may have a substantial impact on visuomotor tasks, difficulties in playing sports in children and locomoting safely in older adults. Furthermore, impaired stereopsis may also limit career options for amblyopes. Finally, stereopsis is more impacted in strabismic than in anisometropic amblyopia. Our review of the various approaches to treating amblyopia (patching, perceptual learning, videogames) suggests that there are several promising new approaches to recovering stereopsis in both anisometropic and strabismic amblyopes. However, recovery of stereoacuity may require more active treatment in strabismic than in anisometropic amblyopia. Individuals with strabismic amblyopia have a very low probability of improvement with monocular training; however they fare better with dichoptic training than with monocular training, and even better with direct stereo training.

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“…Some large-scale studies of selected population show its prevalence to be 1-3.2% [2][3][4][5][6][7][8]. It is the commonest cause for unilateral blindness in the world [9]. The importance of amblyopia lies in the number of life years of blindness and the very little comparative cost requirement to detect, evaluate, and manage it compared with other ocular diseases [9].…”

Section: Introductionmentioning

confidence: 99%

“…It is the commonest cause for unilateral blindness in the world [9]. The importance of amblyopia lies in the number of life years of blindness and the very little comparative cost requirement to detect, evaluate, and manage it compared with other ocular diseases [9]. The principal mechanisms causing amblyopia are deprivation of form sense of vision and abnormal binocular interaction during the critical or sensitive period of visual development [2].…”

Section: Introductionmentioning

confidence: 99%