Vision changes related to sinusitis warrant serious medical attention.
An infectious process involving the paranasal sinuses and orbits, can affect the optic nerve, leading to optic neuritis, an inflammation of optic nerve.
Its main symptom is decreased vision clearness, that may stay as permanent change.
Another condition to be taken in consideration is optic neuropathy.
Blurred vision and progressive vision loss associated with pain around the eye, may indicate compressive optic neuropathy due to a sinus infection (collection of pus from sinus reaches and presses on the nerve).
This optic neuropathy can resemble the optic neuritis.

So, the answer to your question, will be yes, sinus infection can lead to blurred vision, that in some cases remain permanent.

Best wishes!
Marija