Why do you think you would not be able to get both? It is entirely possible that both are appropriate. A child can both be gifted and have a disability / area of need.
OT cannot do vision therapy. You would need a developmental optometrist for that.
To get anything from the school, you need them to do their own educational eval. I'd share the report with them and ask them to assess the needs. Don't say "he needs OT," state what the needs are and what deficits have been identified, and how those are manifest in the school situation, as well as the need for different content. The book From Emotions to Advocacy gives good guidelines for this kind of letter.
DeeDee
