hi. i am 78 yrs old and have had 3 very serious surgeries in the last 6 months; 2 of them heart related. i am now doing well for 2 months but occasionally get double vision when reading. images are vertical and each is clear. when i cover each eye, the image in the other eye is clear-no double vision. the episode usually lasts 2-3 minutes and then sight is back to normal. i have been to neuro and regular ophthalmologists and they find nothing wrong with my sight. all other medical tests are normal. no diabetes, high glucose, etc.