The risk factors for binocular diplopia after uncomplicated cataract surgery in adults were studied to analyse the patterns of ocular motility and clinical causes. This was a retrospective review of 40 patients; 25 female. Onset of diplopia was at a mean age of 73 years (54-88). Patients presented at a mean of 11.2 months (SD 12.6, range 1-55) after cataract surgery. Of 40 cases, 37 had diplopia immediately postoperative and in three, diplopia was delayed to five - six days postoperative. Mean follow-up was 8.4 months (0-53). Left surgery was in 28 and right surgery in 11. Most (37) had vertical diplopia and three had horizontal diplopia. Primary gaze mean horizontal angle was 1.7PD (0-10) and mean vertical angle was 8.4PD (0-25). Topical anaesthesia was used for 37 and general anaesthesia for three. The latter included a case of decompensated esophoria, exotropia due to CI associated with Parkinson’s disease and acquired Brown’s syndrome. All were treated with prisms. Topical cases included decompensated exophoria, vertical deviation due to acquired Brown’s syndrome, vertical deviation due to the surgery with reduced elevation after retrobulbar / peribulbar local anaesthetic injection. The latter were mainly left eyes whilst right eyes had mainly reduced depression. Prisms were given to 35 patients and provided improvement in diplopia. Seventeen went on to have strabismus surgery (16 single muscle). In operated cases, vertical deviation in primary gaze reduced from 14.2PS (SD 5.3) to 2.5PD (SD 5.4). The authors conclude the main risk factor was local anaesthesia and was more common in left eyes. They classified patterns of vertical deviation as 1, deficient elevation with or without over depression of the hypertropic eye (most common and due to inferior rectus contraction) and 2, associated with inferior rectus underaction or superior rectus restriction (common in right eyes).