Does sinus pressure cause blurred vision in one eye?

No: Blurring in one eye is typically a problem (from front to back of the visual system) with the tear film, cornea, anterior chamber, lens, vitreous, retina, orbit, optic nerve, and any connection to the visual cortex. Sinus fullness doesn't directly affect vision.

Blurry: Possibly. Extreme sinus congestion may cause blurred vision. In this case, a a decongestant may help. If the blurred vision persists, call your local ophthalmologist...