ASCRS 2026: The emerging concept of tolerance to refractive error in IOL designs

George O. Waring IV, MD, FACS, of the Waring Vision Institute in Mount Pleasant, SC, highlighted an emerging concept in intraocular lens design—tolerance to refractive error—during his presentation at the American Society of Cataract and Refractive Surgery (ASCRS) 2026 annual meeting, held April 10–13 in Washington, DC. The presentation focused on how this concept may expand current functional frameworks for presbyopia-correcting IOLs and improve understanding of lens performance in the presence of residual refractive error.

Waring structured the talk around three key points. First, he situated the discussion within the functional vision framework advanced by Daniel H. Chang, MD, and the Global Functional Vision Working Group, centered on the QRS concept of “quality, range, and symptoms.” He noted that this collaborative effort involving ESCRS, ASCRS, the Latin American Society of Cataract and Refractive Surgery (LATAMSCRS), and other international organizations aims to “categorize these on a functional basis.” Building on this, the group is now studying an additional component—“the TQRST or tolerance”—to broaden the categorization of simultaneous vision IOLs, including both partial and full depth-of-field designs.

Second, Waring reviewed how contemporary IOL design has evolved beyond traditional optical refinements such as controlling spherical and chromatic aberration. He noted that newer lenses are now being “purpose-designed from the ground up to be more tolerant to changes in effective lens position or other human factors that we can’t totally account for.” In collaboration with Karolinne Rocha, MD, PhD, and research groups at the Medical University of South Carolina, Waring’s team has been evaluating tolerance to refractive error across different astigmatic meridians, including “with-the-rule, oblique, and against-the-rule induction of cylinder.”

The third focus was performance findings. “What were our findings?” he asked, summarizing several key observations from their work. As expected, lenses generally performed better in the presence of with-the-rule astigmatism, and less well with oblique or against-the-rule astigmatism. He reported that “the enhanced monofocal groups tend to be the most resilient in the presence of residual astigmatism,” while some full depth-of-field lenses also demonstrated robust performance under these conditions.

Waring also noted that certain lenses continue to perform well despite residual astigmatism or myopic or hyperopic defocus, an area he described as relatively new in the literature. Importantly, he linked tolerance not only to visual acuity but also to patient experience, noting that it appears to affect “symptoms, the S of the QRS framework.”

He concluded by discussing the possible optical basis for this resilience, including redistribution of light and enhanced contrast sensitivity in regions outside the intended focal point. The next phase of this work, he said, is to “broaden the library and categorization” of how different lenses perform in the setting of residual astigmatism.