Abstract
Purpose :
To illustrate several myths that continue to prevail in IOL calculations even well into the 21st century. To analyze their origins and clarify how they can be debunked and how surgeons and patients alike can benefit from a rigorous analysis.
Methods :
Four myths are analyzed. The myth of the A constant. The myth of the Fedorov foundational IOL equation. The myth of the 30 degrees rotation of a toric IOL for total loss of astigmatism correction. And the myth of the “premium” multifocal IOL.
Results :
The mathematical origin of the A constant is illustrated in a rigorous context and its dependence on several variables demonstrated. This establishes a link between so called theoretical and regression methods and allows for more predictive approaches of outcomes. The myth of the Fedorov foundational equation is traced and the 1967 Fedorov equation is shown to be incorrect. The origin of the error is demonstrated. The 30 degrees rotation myth is also shown rigorously to be just that. The exact solution is presented, Finally a clear assessment of loss of contrast sensitivity and its evolution with time in cataract age patients is presented, debunking the persistent myth that multifocal IOL (under any other name) implantation is a benign intervention.
Conclusions :
A systematic and rigorous approach is taken to illustrate the persistence of several dominant myths in IOL power calculation in cataract surgery, and the clarification of the historical contexts and underlying assumptions that gave rise to such myths. Exact quantitative treatments are proposed to replace myths by science.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.