Fig. 4. A. Iris retractor with hook at one end that retracts the pupillary margin. The hooked end is inserted into the anterior chamber through a limbal incision; then the hook is rotated 90° to engage the pupillary margin. The pupil becomes dilated as the retractor is drawn toward the limbus and held in place by the Silastic disc. B. Iris retractors are placed in the 1:30, 4:30, 7:30, and 10:30 meridians to produce a square-shaped pupil. (A and B, Freeman HM: Current management of giant retinal breaks and fellow eyes. In Glaser BM, Ryan SJ (eds): Surgical Retina, 2nd ed, pp 2313–2338. St. Louis, CV Mosby, 1994)