Amblyopia is a developmental disorder that affects the spatial vision of one or 
both eyes in the absence of an obvious organic cause; it is associated with a 
history of abnormal visual experience during childhood. Subtypes have been 
defined based on the purported etiology, namely, strabismus (misaligned eyes) 
and/or anisometropia (unequal refractive error). Here we consider the usefulness 
of these subclassifications.