Both near and far objects may not be seen clearly. Anisometropia - A difference in the refractive power of the two eyes. Amblyopia is the leading cause of preventable blindness in children. Esotropia - Constant Strabismus is an error in the physical alignment of the eyes. These include corneal, lenticular, and vitreous opacities.
Opacities block light and blur images before they reach the retina.
A common example is a cataract , a lenticular opacity. This child was discovered to have a cataract in each eye. Copyright 1998 Vision Research Corporation.