DeHe,
It sounds like you see the need for the OT but not the VT, I would go ahead with the OT and then see what happens. If there is a subtle vision issue, you can deal with it later. We were seeing issues in first grade -- lots of eye watering, headaches even with glasses, fatigue after close work and complaints about text moving on the page. One of the school's vision screenings caught the tracking issue and recommended further evaluation. We asked for options because DD was struggling. If your DS is not struggling with this, it's hard to justify the expense. At a minimum, I would ask for further explanation and/or a second opinion.
VT is not fun and it's a lot of work (especially if your program requires daily home exercises like ours did). You are trying to change ingrained patterns and coordinate muscles that probably have never worked together. If your kid does not understand the potential benefit (sometimes even if they do understand), it will be torture. I don't even know if I would attempt in with a 4 year old.
