Sounds like your local folks don't specialize in the relevant area in this case.

What you'd look for is someone in developmental optometry with the letters "COVD" after their name.

You can find such a specialist at the "Locate a Doctor" link at http://www.covd.org/Home/ParentResourceCenter/SymptomsChecklist/tabid/279/Default.aspx

In a typical eye exam, they check each eye independently. A developmental optometrist will also explore how the eyes work together (or fail to!) and how the brain processes the information from the eyes. My child passed the local eye doctor tests just fine, and read above grade level, but had strange things going on. A COVD could test and identify what those were.

The good news is that these sorts of things are treatable through therapy (the bad news is that vision therapy is not fun and most find it very tiring). However, these are things that can be improved and then life is much easier. (There are a number of older discussions on here about "vision therapy" if you want to search and learn more.)

Most children with these problems are picked up through achievement problems (e.g. child cannot read). Gifted children can compensate for some of these challenges. A good doctor will listen to you and your child, and test appropriately. Given what you have described, this sort of testing may be very helpful.

You can look at a list of symptoms at http://www.covd.org/Home/ParentResourceCenter/SymptomsChecklist/tabid/279/Default.aspx You can observe if your son engages in other behaviors, such as turning his head to read with one eye, rubbing his eyes, etc. Keep in mind that this list is not developed for PG kids, so some items are not such good indicators as they would be in a more general population.

Many insurance plans will cover some or all of this testing. Some will cover vision therapy as well.