In terms of vision, DS did the WISC IV which had block design and did fine on it (at age 6) but I'm not sure how WPPSI IV block design is different. DS had strabismus at the time due to a brain injury, with one eye not able to track all the way to the right. His block design score was lower than the other perceptual reasoning scores, but he also has fine motor issues which I think played a bigger role. He did a Grooved Pegboard test on the same day (putting pegs into a board and it was timed) and he scored below the first percentile. Meanwhile his block design score was a 13, I think. Not sure if this helps. You can look at any other subtests that involve visual processing and see if those scores are low as well. There is also a test called the Test of Visual Perceptual Skills which an OT did...you could ask about it.
