Morphological appearance and size of contact zones of piggyback intraocular lenses

Purpose: To characterize the morphology, size, and change in size of the co ntact zone of piggyback intraocular lenses (IOLs) of different materials an d optic designs. Setting: Department of Ophthalmology, Vienna General Hospital, Vienna, Aust ria. Methods: In a prospective study, 9 eyes of 7 patients received piggyback IO Ls of the following materials: poly(methyl methacrylate) (PMMA), acrylic, h ydrogel, and silicone. The contact zone between the anterior and posterior IOLs was photodocumented from 1 day to 1 year after surgery using specular microscopy. The contact zone area was measured. Results: A contact zone was present with ail IOL materials studied. The are a of contact, however. differed significantly. With PMMA IOLs, the contact zone was small and surrounded by Newton rings, indicating the tiny gap betw een the IOLs. With IOLs of soft material, such as silicone and hydrogel, it was larger than with PMMA IOLs and had a slightly irregular shape. With fo ldable acrylic IOLs, it was regular, round, and slightly larger than with t he soft materials. The contact area enlarged primarily during the first 3 m onths after surgery. After 1 year, 2 eyes with acrylic piggyback IOLs had a membrane formation around the contact zone and 2 eyes developed Elschnig p earls between the IOLs. Conclusion: In piggyback IOL eyes, the shape and size of the contact zone w ere strongly dependent on the IOL material and optic design. Contact area e nlargement seemed to be induced by capsule shrinkage. Fibrous membrane form ation around the contact zone and Elschnig pearl formation between the pigg yback IOLs were long-term complications of this technique. J Cataract Refra ct Surg 2001; 27: 219-223 (C) 2001 ASCRS and ESCRS.