My DS12 was diagnosed with convergience insuff when he was 1 1/2 years old. The pediatrician said he had a lazy eye and the Opthamologist said there was nothing wrong. I knew something wasn't right so I brought him to Pediatric Optometrist and then he was diagnosed properly. He started vision therapy in small doses at home, using a straw then as he got older we used more intense therapy at home.
I can say that this really really helped my son. Today he's 12 and he's an amazing reader and writer. I was lucky that he started early and was able to do most therapy at home inexpensively. We did not use any of those special glasses. Vision therapy is very time consuming but does produce results, at least in our case. He still has convergience issues but we keep a set of beads(used in VT) that he will use occasionally to remind his brain to use his eyes as a team. When he's over tired or sick the CI will pop up again.
All in all we were happy with the results of Vision therapy.