I didn't read this whole thread, only a few of your posts, but had a couple things to say.

DD had similar WISC IV scores (except PRI and VCI were reversed) when she was 8. PSI was 94. GAI without extended norms was 150. Psych who specialized in gifted kids said it took her an hour or hour and a half longer than other kids to do the test and the "slow processing speed" was apparent. DD is extremely slow when it comes to academic work. She can't seem to do anything academic in a timely fashion, except for the fact that she is a fast and fluent reader. It took her probably 5X longer than the rest of the class to do a cursive packet. Her spec. ed teacher was elated when she finally got it done about 2 months later than everyone else. DD has ADHD--combined type and executive dysfunnction and it is extremely obvious. That being said, she did do just the PSI part of the WISC IV a year after the original test and her score went up to, I think, 118. I don't know if that was her "real" score or if the school psych was so incompetent she didn't administer or score it properly. But if it was accurate, that was a huge jump in 1 years time. So I think you may be over-thinking the score. I would not worry about it unless your DD exhibits symptoms like my DD. Her WJ scores were also not anything that you would expect from a child who scored a 150 GAI on the WISC (110 or below was considered an extreme discrepancy in the regression tables, at least in terms of qualifying for services based on having a learning disorder).

DS had a very extreme case of vision issues when he was in kindergarten. He had a traumatic brain injury and one eye was literally stuck turned inward, and didn't track at all for months. Prism glasses would have been useless because the convergence issue was way too severe and he had extreme double vision. Like two identical clocks on the wall 5 feet apart. Two identical books side by side when he read. He would reach for a balloon ribbon and grab at air, the "double" about a foot away from where the real balloon was. He was somehow able to read fluently with an eye that didn't move even when we patched his normal eye. I don't think it was all that easy or comfortable for him but he was able to do it. So when I hear people say that their child has reading difficulty because of their visual convergence issues, I am very skeptical. His eyes are now aligned but he has obvious tracking issues when he's examined. His eyes look like they are moving independently, kind of like a lizards (this is not obvious except when he is asked to track a moving object and people are watching his eyes). He claims that he has no problems seeing the words on the page and he reads books with tiny print very quickly. Reading achievement scores are always 98th-99th percentile, similar to his cognitive ability. I am not sure if any of that info is relevant to your situation but thought I'd share our experience. Vision therapy has been suggested to me but I have no proof that his vision tracking issues are affecting him and would not shell out any money unless insurance paid for it.