ESCRS 2026: Why standard visual acuity tests miss multifocal IOL differences

At the 2026 Congress of the European Society of Cataract and Refractive Surgeons (ESCRS), held 11–15 September in London, Jascha Wendelstein, MD, argued that standard visual acuity testing may be too blunt an instrument to capture real differences between multifocal intraocular lenses (IOLs).

Benchmark new lenses against your own outcomes

Wendelstein, a cataract and refractive surgeon at the IROC Institute in Zurich, Switzerland, said surgeons should treat their own outcomes data as the benchmark for evaluating a new lens, rather than assuming newer technology automatically outperforms older options. He recommended comparing defocus curves directly against lenses already in use, and weighing real patient performance, before adopting something new into practice, then sticking with whichever lens performs best.

Standard letter charts miss the photopic-mesopic gap

Wendelstein said that when his group compared visual acuity measured with ETDRS letters to actual reading-speed performance, the letter-chart testing did not reveal the drop between photopic and mesopic conditions that reading-speed testing did, even at near point. He said the ETDRS letters are "too easy" to capture the smaller differences between lenses—the kind that leave a patient able to read, but not fully satisfied.

The case for functional visual acuity testing

For Wendelstein, reading speed is currently the best available proxy for functional visual acuity, because it combines visual acuity and contrast sensitivity in a way that reflects real-world performance. He said better tests are still needed to isolate these smaller differences between lenses, and that reading speed is "a good starting point" rather than a finished solution for functional visual acuity testing overall.

Looking ahead: distance and intermediate reading speed

Wendelstein said he wants to extend reading-speed testing beyond near vision. He is aiming to help develop new photopic and mesopic methods for assessing distance and intermediate reading speed as well, so that future comparisons between multifocal lenses are not limited to near-vision performance alone.