**1. Introduction**

Secondary intraocular lens implantation is defined as implantation of an intraocular lens following an initial surgery that resulted in aphakia or a deficient intraocular lens. The indications for secondary intraocular lens insertion have evolved with improved surgical outcomes of modern cataract surgery. Newer surgical techniques and lenses has also advanced the field of secondary intraocular lenses. The first wave of secondary intraocular lenses to be implanted was the anterior chamber intraocular lens (ACIOL) [1]. Secondary intraocular lenses can now be implanted in a variety of anatomic locations with different techniques used to support the lens (sutured, iris claw, etc.). Specifically, sutured IOL and intrascleral fixation techniques have been gaining popularity. Szigiato et al. found a 538% increase in secondary sutured IOL techniques from 2000 to 2013 [2]. However, with the advent of several new techniques there is no clear guidance for the best technique for secondary IOL placement. This chapter aims to discuss the variety of secondary intraocular lenses, the indications for use, and surgical considerations.
