I have had surgery for macular pucker in my right eye that developed from a torn retina. In my left eye I have the same condition which is stable with some minor image distortion ( line is curved up in the center). I now have hypertropia. The image in my left eye is higher than my right resulting in double vision problems. I have observed that prism can correct the image for a split second, but the right eye if I stare at the image will drift down. Additional prism will start with my right eye image higher and with staring will drift down and merge. What is the cause of this drifting and is there a solution.