Modern IOL calculation formulas remain the best choice

Modern intraocular lens (IOL) power calculations using the latest-generation formulas remain the best choice for ophthalmic surgeons today, Graham Barrett MD, Australia, argued during the Journal of Cataract and Refractive Surgery Symposium ‘Controversies in Cataract and Refractive Surgery’ session yesterday.

Dr Barrett, who created the widely-used Barrett formulas (based on Gaussian formulas) for IOL power calculation, maintained that artificial intelligence does not replace nor is better than traditional formulas.

He said that using the latest-generation traditional formulas with the more accurate data and measurements we have access to today, and utilising additional parameters has made calculations better and more accurate. Looking to the future, he said that formulas could add parameters like age and race to further refine accuracy.

Dr Barrett cited a number of comparison studies of various formulas to support his argument, including data comparing the prediction accuracy of 297 consecutive cases using two or three parameters (older traditional formulas) versus five parameters (Barrett Universal II formula), which showed superior predictions for his formula across all measurements.

“I think there is a misconception that the tag ‘AI’ endows some magic to the process of assessing data to refine outcomes,” he commented, adding that no one really understands what happens exactly inside the “black box” of artificial intelligence algorithms.

Dr Barrett said while there were benefits to both approaches, he believes the latest traditional theoretical formulas utilising paraxial ray tracing and polynomial regression are superior. The best formulas “should be flexible enough to be able to utilise more useful information and add in new parameters as they become available” to further improve their accuracy, he said.

Concluding, Dr Barrett said theoretical formula versions that utilise “every drop of knowledge” are the best choice for the most accurate IOL power calculations across the range of surgical needs.

Tags: iol power calculation