A new peer-reviewed study published in BMC Ophthalmology presents the first independent optical bench evaluation of the Extend™ monofocal plus intraocular lens (IOL), providing an in-depth assessment of its optical performance under standardized laboratory conditions. The study was published in June 2026 and compared the Extend™ IOL with the TECNIS Eyhance (ICB00) using ISO-compliant optical benchmarking methods.
The research was conducted by Frederick Kremser, Weijia Yan, Prof. Ramin Khoramnia, Prof. Gerd U. Auffarth, and Dr. Grzegorz Łabuz at the David J. Apple International Laboratory for Ocular Pathology, Heidelberg University.
Unlike conventional enhanced monofocal IOLs that rely on higher-order aspheric surfaces or diffractive optics, the Extend™ IOL incorporates the Bessel beam principle through a central conical axicon surface. This unique optical design is intended to extend the functional range of vision while maintaining a single, far-dominant focal peak.
Using the OptiSpheric IOL PRO2 under International Organization for Standardization (ISO) conditions, the investigators evaluated modulation transfer function (MTF), point spread function (PSF), through-focus performance, and image quality. The results demonstrated optical performance comparable to the reference lens across all evaluated parameters. At a 3 mm aperture, the Extend™ IOL achieved an MTF of 0.38 ± 0.01 at 50 lp/mm, compared with 0.36 ± 0.01 for the TECNIS Eyhance. Both lenses produced identical distance visual acuity at far focus (−0.09 logMAR), with nearly overlapping through-focus visual acuity curves and comparable point spread function profiles.
The findings demonstrate that the Extend™ IOL delivers optical performance comparable to the established reference lens while employing a fundamentally different optical concept based on the Bessel principle.
We congratulate the authors on this important contribution to the scientific literature and thank them for advancing the understanding of next-generation enhanced monofocal IOL technologies.
Read the open-access publication: BMC Ophthalmology article
