2020–2021 BCSC Basic and Clinical Science Course™
3 Clinical Optics
Chapter 6: Intraocular Lenses
Optical Considerations for Intraocular Lenses
Piggyback and Supplemental Intraocular Lenses
When an IOL is inserted into an eye that already has an IOL in place, the second IOL is called a piggyback IOL. The piggyback IOL can be inserted at the time the first IOL is implanted to produce a high power that is commercially unavailable. It can also be inserted secondarily to correct a postoperative refractive error. Computer programs can be used to calculate the power of the second IOL and to make adjustments, which may be needed if the posterior IOL is displaced posteriorly. However, these adjustments are minor, and using one of the following formulas is the easiest way to calculate them:
where P is the needed power in the piggyback lens, and error refers to the residual refractive error that needs to be corrected.
Excerpted from BCSC 2020-2021 series : Section 3 - Clinical Optics. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.