Simplified updates on the pathophysiology and recent developments in the treatment of amblyopia: A review

Abstract

Amblyopia is the most common cause of monocular visual impairment affecting 2-5% of the general population. Amblyopia is a developmental cortical disorder of the visual pathway essentially due to abnormal visual stimulus, reaching the binocular cortical cells, which may be multivariate. Ganglion cells are of two types: parvocellular (P cells) and magnocellular (M cells); they are the first step where the light energy is converted in to neural impulse. P cells are involved in fine visual acuity, fine stereopsis, and color vision and M cells are involved in gross stereopsis and movement recognition. Strabismus, refractive error, cataract, and ptosis, occurring during critical period are highly amblyogenic. The critical period extends from birth to 7--8 years. The earlier the clinically significant refractive error and strabismus are detected and treated, the greater the likelihood of preventing amblyopia. Treatment for amblyopia in children includes: optical correction of significant refractive errors, patching, pharmacological treatment, and alternative therapies which include: vision therapy, binocular therapy, and liquid crystal display eyeglasses are newer treatment modalities for amblyopia. Age of starting the treatment is not predictive of outcome, instituting treatment on detection and early detection plays a role in achieving better outcomes. This review aims to give a simplified update on amblyopia, which will be of use to a clinician, in understanding the pathophysiology of the complex condition. We also share the cortical aspects of amblyopia and give recent developments in the treatment of amblyopia.

Looking beyond occlusion: A novel perspective for amblyopia treatment

“…For many decades the most widely used treatment modality for amblyopia has been patching or optical or pharmaceutical penalization of the unaffected eye to stimulate visual development in the affected eye. [ 1 15 ] Of these, patching is the most popular, but is found to be successful in only 50%–75% of patients due to compliance issues and the inherent difficulties of patching the normal eye when the amblyopic eye has very poor vision. The recovery of stereopsis is also questionable with patching.…”

“…Amblyopia is a developmental disorder of the occipital cortical binocular cells, due to abnormal action potentials (in time or amplitude) reaching the binocular cortical cells from the retina of one or both eyes, during early development. [ 1 ] Occlusion therapy has been the most popular treatment option for amblyopia for many decades. [ 1 2 3 ] The results have been variable and inconsistent due to differences in age, etiology, and initiation and duration of treatment.…”

“…[ 1 ] Occlusion therapy has been the most popular treatment option for amblyopia for many decades. [ 1 2 3 ] The results have been variable and inconsistent due to differences in age, etiology, and initiation and duration of treatment. [ 4 ] Moreover, monocular occlusion may not actively improve the binocular cooperation and stereopsis.…”

Abnormal interhemispheric functional connectivity in patients with strabismic amblyopia: a resting-state fMRI study using voxel-mirrored homotopic connectivity

“…In addition, these areas showed activity in various strabismus studies. Therefore, impairment of SA function leads to abnormalities in the spatial characteristics of cortical neurons and involves multiple brain regions, resulting in a combination of multi-directional and multi-level damage to visual nerves [ 11 ]. The study conducted by Rossion et al [ 12 ] revealed that functional impairment of SA is associated with abnormalities in the spatial characteristics of cortical neurons and involves multiple brain regions.…”

Effect of regulation of the NRG1/ErbB4 signaling pathway on the visual cortex synaptic plasticity of amblyopic adult rats

“…Amblyopia could result in reduced visual acuity in one eye, decreased stereovision ability, and impaired binocular interactions. [1] Amblyopia treatment can be optimized during the early critical period of visual cortex development.…”