I am a glaucoma specialist but deal with patients who have diplopia (double vision) after many eye surgeries, including cataract surgery. First, we must assume that the surgery was performed correctly and the IOL implant (new lens replacing the cataract) is properly in place. Any competent eye doctor can make that assessment. Second, was the patient left with a large spectacle prescription difference between the eyes? If the power of the IOL was incorrectly calculated and a large difference results after lens implantation, than double vision will result. A surgical lens exchange may alleviate the problem. What was the vision like prior to cataract formation?If there was a prior problem (strabismus (crossed eyes), anisometropia (large difference in spectacle prescription between eyes), amblyopia (lazy eye), or a multitude of neurological problems the removal of a cataract could open the proverbial "can of worms". I would suggest seeking the opinion of a well respected optometrist or ophthalmologist in your community to determine the cause of the diplopia. Only then can a reasonable solution be found. The solution may well be "special lenses" prescribed by an expert in this problem. Good luck!