My niece had an inherited congenital defect where one eye was weaker than the other, which if untreated, she would have eventually gone blind in the weaker eye.

My niece had an inherited congenital defect where one eye was weaker than the other, which if untreated, she would have eventually gone blind in the weaker eye. Fortunately it was discovered in time. For quite some time she wore a patch over her good eye, until the bad eye strengthened itself to carry its share of the load. I dont know if the defect was in the eye itself or in the neural pathways, but I suspect it was the eye itself and the strengthening was in the neural pathways.