Amblyopia, also called lazy eye, is a disorder of sight in which the brain fails to process inputs from one eye and over time favors the other eye. It results in decreased vision in an eye that otherwise typically appears normal. Amblyopia is the most common cause of decreased vision in a single eye among children and younger adults. Symptoms Symptoms of amblyopia can be hard to notice. Kids with amblyopia may have poor depth perception - they have trouble telling how near or far something is.