We're likely to take a similar path this summer with DS8. We had hoped that having his vision addressed with patching two years ago would've helped the handwriting and fine motor will catch up on its own. But not so much.
Meanwhile, I've read a ton on this, particularly in trying to mark out how much is visual related and how much just the way his brain ticks. Dysgraphia literally would be a problem with writing, but specifically most of the references point to a core language processing issue that includes a spectrum of other flags like spelling problems and challenges in generated complex writing and such.
I think there is an interaction in there between the visual system and the neurological coding that can get thrown off if the eyes aren't working together during some critical growth phases. There may also be interactions with the brain's general organization; such that a kid wired more towards patterns rather than details has a harder time bouncing back or may be more likely to have a wider range of dysgraphia symptoms.
So, other than patching to rein his amblyopia in, we haven't gone towards vision therapy.
As to IQ, my DS8 didn't have the WISC, but on the SB5 which is designed to be half verbal and half non-verbal section he had at least a fifteen point increase in verbal compared to non-verbal components. But you'd likely need to look at the subsections on the WISC to determine if your son is similarly impacted. I'd expect things like block design to be significantly lower if it is the case.
