Double vision, nauseated at first, has to hold onto wall while in the house, falls without support. Had cat scan and it showed negative for stroke. On high blood pressure medicine. 56 yr. Old male. No answers from doctors so far. What could be the cau

I . I would recommend returning to the er as soon as possible. The combination of ataxia (staggering) and diplopia (double vision) would indicate a stroke in the brainstem, which would not be visible on a ct scan. A MRI is the diagnostic test of choice.
You . You may want to consider a visit to a neurologist with that combination of symptoms, especially if the double vision is only present with both eyes open at once. This would indicate a nerve problem with a nerve controlling one of the muscles that moves the eye.
Double . Double vision indicates that your two eyes are not alligned. This can be secondary to the muscles that control your eye movements or to the nerves that control the muscles. I recommend seeking a neuro-ophhthalmologist for a full workup.