I've also had chronic sinus symptoms, which have affected my vision. Like both of you, I had pain and pressure, which made me experience blurred vision. I spoke to numerous experts about this, and had tests done, and the consensus seemed to be that my vision was unchanged, according to objective metrics. I think this quite likely implies that the eye's visual acuity remains perfectly fine, but the fluid pressure affects the visual signal elsewhere -- for instance by putting pressure on optic nerves carrying the image to the brain.
At any rate, I've found that through frequent nasal irrigation, at first with a simple solution and now with Sinox (to much greater effect), I can do a decent job of managing my sinus comfort. Stress relief techniques can also help. The overall result is that I feel and see a lot better.
You might try nasal sprays and other options, to discover what works best for you!