S.M.
Hi J.,
My son has been wearing glasses since he was 2 months old. He is now 18 months and since he started so young he has no problem keeping them on since they have now become a part of him. He has metal framed glasses now but when he was younger he wore the plastic ones from solobambini.com, they were great. A great eyeglass shop that specializes in young children is "Eyes for Kids" in San Diego, they are located off of the 805 at Clairemont Mesa. They work a lot with little ones and might have some good advice to help you with your son keeping his glasses on.
You might want to talk with your opthamologist about contact lenses. I know this was an option for us but we didn't want to deal with it. But in your situation, it might be necessary.
Good luck!