What is the definition of amblyopia?

Amblyopia, commonly referred to as "lazy eye," is defined as decreased vision in one eye that arises due to a lack of proper coordination between the eye and the brain during early childhood development. This condition often occurs because the brain favors one eye over the other, leading to underdevelopment of the weaker eye. The disparity in visual acuity results from abnormal visual experiences during critical periods of visual development, which might be due to various factors such as strabismus (misalignment of the eyes), refractive errors, or other occlusions.

While other options present conditions that pertain to vision, they do not accurately describe amblyopia. Sudden loss of vision indicates a different set of conditions and is more acute rather than a gradual process associated with amblyopia. The inability to align eyes relates to strabismus, which can be a cause of amblyopia but is not the definition of the condition itself. Chronic eye pain does not correlate with amblyopia, as this condition primarily involves a discrepancy in visual processing rather than pain or discomfort. Thus, the correct choice captures the essence of amblyopia as a developmental issue affecting vision in one eye due to neural factors.