Breathe. In. Out. In. Out.
More information is always better than none. Having the results of this screening now gives you a framework to think about your child as well as a starting point from which to ask more questions.
Why was this screening done in the first place, and does this test (never heard of it) test for the types of struggles that you observe in your son? Do the screening results synch with what you observe about your child? Does the whole word discrimination struggle seem to align with anything you observe in his development?
How is his reading coming along? Is it outside the range of what you would expect considering his vision struggles?
How is he doing in school? What types of struggles do you observe? Something more than just reading? Are there writing struggles, and if so, of what nature?
Don't try to answer all those questions all at once. Please. Whittle away at those questions are you start to wrap your head around what struggles your son might or might not have.
I have found the getting the results of testing to be almost liberating, as they really did capture and describe why school was such a miserable place for my DD. She's been doing Orton-Gillingham for 4 months now and doing fabulously. For DD, has removed a lot of the difficulty DD had in expressing herself in writing to reveal an incredibly talented writer.