Piggyback intraocular lens with exchangeable optic.

The exchange of a posterior chamber intraocular lens (IOL) is difficult if the lens is transsclerally or iris fixated or if a large posterior capsulotomy exists. A piggyback IOL system was developed that allows adjustment of refraction in situ without removing the primarily implanted IOL. The system comprises a posterior chamber IOL and a separate, exchangeable optic. Three succeeding designs were implanted in human, donor eyes. The piggyback system's optical performance exceeded the requirements for conventional posterior chamber IOLs. Thus, the lens could be used in eyes in which postoperative refraction is likely to change or is incorrect (e.g., in children or cases of combined cataract extraction and corneal implantation.