I'm not a brain surgeon but I do like to dabble.
Although my patient has no recollection of a knock to the head, led poisoning or any other such incident, they do indeed suffer recurring, intermittent double vision. They were advised by an actual expert to wear an eye patch, covering the good eye, and in theory this would remind the offending eye which direction it should be pointing in and thus restore normal balanced stereo vision.
As a precaution, I administered a course of bloodletting from a Cumberland sausage by way of a gill of leaches.
Step 1: Double Vision Eye Patch Spectacles Gizmo 1.
In this particular case identifying the problematic eye wasn't exactly straight forward. They both appeared to swivel independently and in their own orbits. For this reason I chose to adapt a pair of specs so that each eye could be covered and uncovered as necessary and until the wonky one had been noted.
I took one pair of really rubbish sunglasses and removed both lenses.
Step 2: Double Vision Eye Patch Spectacles Gizmo 2.
Using the removed lenses as templates, I cut two of the same shape from a piece of sturdy, black cardboard.
Step 3: Double Vision Eye Patch Spectacles Gizmo 3.
I applied a small blob of tacky blue stuff to the top corners of the frames to affix the patches as appropriate. The appliance was then attached to the patient.
Step 4: Double Vision Eye Patch Spectacles Gizmo 4.
The patient has reported a rapid and profound improvement.