Extraocular muscle imbalance and diplopia after retina surgery have been previously reported, but the etiology is still controversial. In order to better understand the cause of strabismus after retinal surgery, the authors retrospectively studied 30 patients with persistent strabismus following retinal surgery and combined the result about seven patients of strabismus after retinal surgery in the previous report. Results showed multiple etiologies for the strabismus. Causes of strabismus included fat adherence syndrome (14 patients), non-specific restrictive adhesion (11), displacement of superior oblique tendon (2), scleral explant interfering with ocular motility (1), lost or slipped muscle with adhesion (2), sensory strabismus (2), macular pucker causing ectopic fovea (2), and previous strabismus before the retinal surgery (3). Knowledge of the varieties of abnormalities that can cause strabismus and diplopia will help both the retina and strabismus surgeon prevent and treat strabismus after retinal surgery.