Laser IOL Power Adjustment

Laser-adjustable intraocular lenses (IOLs) are now entering clinical studies and have the potential for in vivo diffractive adjustment into any distance or multifocal profile, according to Ronald R Krueger MD. Further developments in laser-adjustable lenses, as well as the already commercially available light-adjustable lenses, are likely, he added.

While the refractive performance of IOLs has improved greatly in recent years, the accuracy of fixed power lenses is still limited by factors including biometry problems, mechanical IOL positioning, and wound healing, Professor Krueger noted. Indeed, a EUREQUO study of more than a quarter million surgeries published in 2018 found that while about 73% of eyes fell within 0.50 D of target refraction, the absolute mean prediction error in spherical equivalent was 0.42 D.¹

Adjusting lenses after implementation has the potential to further reduce errors, Prof Krueger said. The Light Adjustable Lens (RxSight), which was approved in the US in 2017, has demonstrated how effective the approach can be, increasing the percentage of patients testing with 0.50 D to 98% in an early trial and 92% in the FDA approval trial.^2,3 About 75% of recent patients opt for blended vision or monovision, according to company research.⁴

Refractive Index Shaping

However, the Light Adjustable Lens requires a specific polymer lens designed to react to ultraviolet light to adjust its power. Lasers could alter the refractive power of any acrylic lens type and even induce multifocality through a process called Refractive Index Shaping (RIS).

RIS uses a 520-nm green femtosecond laser to create a thin layer of refractive index change, forming a diffractive Fresnel prism. Refractive index changes allowing corrections as fine as 0.10 D are made inside the IOL by laser bursts that do not reach ablation strength, so the shape of the lens is not affected and no photoablation occurs.

In an ongoing study by Pavel Stodůlka MD, PhD, 18 eyes of 9 patients implanted with monofocal Tecnis ZCB00 (Johnson & Johnson) lenses received a 40-second outpatient RIS treatment that changed their lenses into diffractive multifocal lenses. One month after treatment, patients had good near vision without sacrificing distance visual acuity, Prof Krueger said. While the early results are positive, more patients and longer follow-up are required to further test the concept.

Movable lenses

Another approach to lens adjustment is argon laser-directed lens movement, Prof Krueger said. A hydrophobic IOL incorporating a spring-loaded nitinol cradle is implanted in the eye. An argon laser then allows the lens to be moved forward or backward by selectively releasing spring tension to correct errors after implantation. The lens has been tested in rabbits, and a human trial is about to start, Prof Krueger said.

“The global trend for personalised medicine will fuel further development in laser and light adjustability in the future,” Prof Krueger concluded.

Prof Krueger made his comments at the 2025 ESCRS Annual Congress in Copenhagen.

Ronald R Krueger MD is McGaw Professor and Chair of the University of Nebraska Medical Center Department of Ophthalmology and Visual Sciences, and Director of the Stanley M Truhlsen Eye Institute, both of Omaha, Nebraska, US. ronald.krueger@unmc.edu

1. Lundstrom M, et al. J Cataract Refract Surg, 2018 Apr; 44(4): 447–452.

2. Hengerer FH, Dick HB, Conrad-Hengerer I. Ophthalmology, 2011 Dec; 118(12): 2382–2388.

3. Summary of Safety and Effectiveness Data. US FDA 2017. PMA P160055.

4. RxSight PMCS-002 Clinical Outcomes of Patients Bilaterally Implanted with LAL.