What is Amblyopia?
Amblyopia is a vision dysfunction which impairs the vision in one eye, owing to a lack of coordination between the eyes and the brain.
The condition is generated by various causes: Strabismic amblyopia (misaligned eyes), refractive amblyopia (nearsightedness, farsightedness, or astigmatism), deprivational amblyopia (disorders such as congenital cataract) and anisometropic amblyopia (unequal focus of the two eyes creating a chronic blur in the affected eye).
Amblyopia is estimated to affect 2.5%–5% of children, and is the most common cause of monocular visual impairment among young and middle-aged adults.
The prevailing amblyopia treatments are occlusion therapy or atropine penalization therapy, each of which involves significant shortcomings.
Occlusion (patching), the more traditional and prevalent treatment for binocular vision dysfunction , neutralizes the healthy eye in order to stimulate the weak eye. This amblyopia treatment requires 2 to 6 hours daily, and involves high levels of stress for children as well as their parents, especially at young ages when the child often simply pulls off the eyepatch. Only ~60% of the children actually reach normal vision with occlusion therapy.
Around 35% of children treated with occlusion therapy reach peak visual acuity and then regress due to lack of long-term adherence to the therapy by both children and parents. Patching may also cause irritation and allergy.
Atropine, a cholinergic antagonist, is administered in drops into the non-amblyopic eye, generating pupil dilation and reduced accommodation, therefore causing the amblyopic eye to function in near-vision tasks. Atropine drops may be hard to administer in children, and are associated with rare but severe side effects, from flushing and dry mouth to hyperactivity, tachycardia and even seizures. Atropine also brings relatively slower vision improvement.
Thanks to new insights on cortical processes relating to amblyopia, innovative treatment approaches are being developed,
relating to visual stimulation of both eyes, with the objective of improving binocularity as well as visual acuity in the amblyopic eye. These channels are being explored in case series or randomized controlled trials, while also attempting to adapt the treatments for children.