Help-strabismus with my toddler

My 3 1/2 year old son has been recommended to have eye muscle surgery. We have been going to a pediatric opthmologist for 2 years. Ashton (my son) started wearing glasses to correct his strabismus and amblyopia. He started with glasses at 1 1/2, we have increased his prescription strength (so much that Ashton often looks over his glasses), did the atropine gtts for 2 months, and now we have worn an eye patch for 4 hours every day for the last 3 months. The eye patch has corrected his vision. But, his inward eye turn in constant and has not improved. The ped opthomologist is recommending surgery. I have read that vision therapy can help. Has anyone been successful with toddlers? Any recommendations/advice??