Sinus infection may cause dizziness and blurred vision. It is a common phenomenon. If you suffer from colds or allergies, you may experience dizziness too. Dizziness is the state of lightheadedness. If sinus infection reaches a point, it may lead to migraine or headache. So you'd better see the doctor immediately.
Sinus infection can be associated with dizziness. You may have the feeling of instability which will cause nausea sometimes. If the infection is in the maxillary sinus, the change of the vision may lead to dizziness. If not treated it immediately, sinus infection may lead to blurred vision.