I think that will also be key information for understanding your DS. If there's no change, then you know there's something more than the vision going on, or that the VT wasn't effective.
As for additional testing, I think you need his actual level (evaluate on DRA until the teacher finds an "instructional" level) along with the DIBELS/AIMSweb. Note that DRA is not nationally normed, and therefore makes it difficult to compare to predicted performance from the WISC, which is why you might also want to do the reading portions of the WIAT as well if there are questions or discrepancies from the WISC and other reading assessments.
As for the writing, there are picture copying tests that help tease out the underlying cause of the reversals. I understand those less as DD didn't show her reversals in the testing (most severe in the first 3-4 weeks of school each year, even now in 5th grade).
