I would second polarbear. Our DS passed his conventional ophthalmologist exams with flying colors, including an extra convergence check I requested because I had convergence issues myself as a child. So I set that worry aside. When he began to refuse seatwork this year we learned the letters were dancing on the page. The developmental optometrist picked up major issues with convergence, accommodation, and tracking. He has been reading well beyond grade level - but with far too much effort.
I was highly skeptical myself (and my DH more so) until sitting in on the exam and watching the optometrist systematically zero in on where DS was having trouble.
