Rethinking astigmatism analysis for intraocular lens-based surgery (Also contains link to download Astigmatism Double Angle Plot Tool)
Astigmatic change analysis after IOL-based surgery (cataract surgery with IOL, or refractive lens exchange) is challenging for several reasons. There is a range of analytical approaches, analyzing astigmatic change after an IOL surgery is necessarily more complex than in corneal refractive surgery, and there are 4 scenarios in which cataract surgery alters ocular astigmatism (nontoric IOL without corneal relaxing incisions, nontoric IOL with corneal relaxing incisions, toric IOL without corneal relaxing incisions and toric IOL with corneal relaxing incisions).
In this guest editorial from the Journal of Cataract & Refractive Surgery®, October 2018, the authors explore this controversial subject and suggest standardised terminology and outcome report standards for, and a hybrid approach to, analyzing astigmatic change following IOL-based surgery.
An astigmatism double-angle plot tool is also available for download (see links to the right), as well as instructions for its use. The authors argue the benefits of this method, as astigmatism is a vector—with a magnitude and an orientation—that therefore requires doubling of the angle to transform the astigmatism data into 360-degree Cartesian coordinates.