At APACRS 2025, Professor Thomas Kohnen delivered the Arthur Lim Lecture, tracing the evolution of phakic IOLs and their growing place alongside lasers and lens extraction.
At APACRS 2025 in Ahmedabad, Professor Thomas Kohnen (Germany) took the podium for the prestigious Arthur Lim Lecture, guiding the audience on a tour through the past, present and future of phakic intraocular lenses (IOLs).
Once considered a niche tool for select cases, phakic IOLs are now reshaping how surgeons manage high myopia, presbyopia and the tricky group of young patients caught between laser correction and refractive lens exchange. With data, history and sharp clinical insight, Prof. Kohnen showed how these lenses are no longer on the sidelines but moving into the mainstream of refractive care.
From Frankfurt to Ahmedabad
In front of a packed auditorium at APACRS 2025, Prof. Kohnen delivered the Arthur Lim Lecture, an honor reserved for pioneers who have shaped cataract and refractive surgery. Chair of Ophthalmology at Goethe University and Editor-in-Chief of the Journal of Cataract & Refractive Surgery, he brought more than 25 years of surgical experience, 2,500 phakic IOL cases, and a research legacy of over 300 publications to the stage.
His talk, Bridging Laser and Lens Extraction: The Evolution of Phakic IOLs, traced the arc of innovation from historical milestones to AI-guided precision. “You only see what you know,” Prof. Kohnen reminded the audience, a fitting Goethe line from Frankfurt, shared with a global gathering in Ahmedabad.
The global squeeze of myopia
To set the stage, Prof. Kohnen spotlighted the global myopia epidemic. By 2050, half the world’s population may be myopic, he warned. In India alone, more than half of all visual impairment stems from uncorrected refractive error. He illustrated the lived reality with striking simulations from a barely noticeable blur at –1.0 D to just 6% functional vision at –8.0 D.
His message was that high myopia dramatically reduces quality of life and demands solutions beyond laser correction or lens extraction. “We always will have these patients,” Kohnen cautioned. “Even with the best diagnostics and AI, we cannot 100% predict ectasia.” For many, phakic IOLs provide the missing piece.
READ MORE: The Myopia Enigma
Lasers as a foundation with limits
Prof. Kohnen next turned to the well-trodden ground of corneal refractive surgery: photorefractive keratectomy (PRK), laser-assisted in situ keratomileusis (LASIK), small incision lenticule extraction (SMILE), and newer lenticule-based platforms like KLEX and CLEAR. These techniques have become routine, yet they come with caveats: small optical zones, the lingering threat of ectasia and the complications they pose for future IOL calculations.
Even sophisticated AI-driven prediction models only improve, but not eliminate, the risks. “Although we have very good diagnostics, we still cannot 100% predict it,” Prof. Kohnen noted, emphasizing that corneal biomechanics differ too much from patient to patient. For that reason, he argued, the field still needs surgical alternatives that preserve corneal integrity. Enter phakic IOLs.
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Why lens exchange can be risky business
Refractive lens exchange (RLE) has roots stretching back to Vienna in the 1890s, but in today’s refractive landscape it’s still a contentious option. Prof. Kohnen cautioned against its use in young high myopes, especially those with long axial lengths or signs of peripheral retinal pathology. “You remove the lens, you create space, and the vitreous comes forward,” he explained. “That is one problem we don’t like to see—retinal detachment.”
In these cases, the risk of detachment may double, making RLE unsuitable as a first-line intervention. For patients with lattice degeneration or similar peripheral changes, Prof. Kohnen advised against RLE entirely.
A tour through phakic history
The heart of the lecture was the evolution of phakic IOLs themselves. Prof. Kohnen walked attendees through three distinct generations:
- Iris-fixated lenses, such as the Artisan (Ophtec; Groningen, Netherlands), were early innovators but raised concerns about endothelial cell loss and pigment dispersion.
- Angle-supported lenses showed initial promise but were ultimately withdrawn due to high explantation rates and long-term endothelial complications.
- Posterior chamber lenses, particularly the Visian ICL (Staar Surgical, California, United States), proved to be the breakthrough, especially after the addition of the KS-AquaPORT, which reduced anterior subcapsular opacification.
“With the advent of the AquaPORT, this lens became safe,” said Prof. Kohnen. Five-year data now show cataract formation rates under 1%. Today, more than 3 million ICLs have been implanted globally, making them the leading choice for phakic IOL surgery.
Posterior chamber and the power of precision
Posterior chamber phakic IOLs now dominate the field, offering excellent uncorrected visual acuity, minimal disruption to ocular anatomy, and an invisible cosmetic profile. According to Prof. Kohnen, their success hinges on accurate vault prediction, which has come a long way from early white-to-white sizing.
Today, sulcus-to-sulcus imaging and AI-based tools like the ICL Guru (Revai; California, United States) and the LASSO formula (Least Absolute Shrinkage and Selection Operator) enable 97% accuracy in sizing. “Artificial intelligence allows us to predict in 97% of cases,” Prof. Kohnen said. “It is a great strategy for us to become better.”
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Toric customization has also become standard, with 80–90% of posterior chamber phakic IOLs correcting astigmatism. But he issued a word of caution: “The machines sometimes don’t recognize phakic lenses and think it’s the natural crystalline lens”—a mistake that can skew cataract biometry.
Into presbyopia and reversibility
Prof. Kohnen also touched on emerging applications in presbyopia. Newer phakic IOLs, such as the EVO Viva (Staar Surgical, California, United States) and the Artisan Presbyopia (Ophtec; Groningen, Netherlands), use extended depth of focus (EDOF) optics to address distance and near vision simultaneously. Glare and halos remain concerns, but these designs are a promising step toward presbyopia correction in younger patients.
READ MORE: Ophtec’s Phakic IOL for Presbyopia Receives CE Mark Approval
For extreme myopia, bioptics (pairing ICL implantation with LASIK) still plays a role. Most notably, phakic IOLs offer something few other surgical options can: reversibility. “These lenses can be removed if needed,” said Prof. Kohnen. With some now approved for myopia as low as –1.0 D, the landscape of refractive options is expanding.
“You only see what you know.”
Prof. Kohnen closed the Arthur Lim Lecture by positioning phakic IOLs not as a backup plan, but as a central pillar in refractive care that stands alongside lasers and lens extraction rather than apart from them. “It is a reversible option in refractive surgery,” he said. “More patients can be helped. It broadens our spectrum.”
From AI-based vault prediction to expanded indications in high myopia, Prof. Kohnen’s lecture made it clear that phakic IOLs are no longer on the fringe. They’ve moved to the center of the refractive stage.
Editor’s Note: The 37th annual meeting of the Asia-Pacific Association of Cataract and Refractive Surgeons (APACRS 2025) is being held from 21-23 August in Ahmedabad, India. Reporting for this story took place during the event. This content is intended exclusively for healthcare professionals. It is not intended for the general public. Products or therapies discussed may not be registered or approved in all jurisdictions, including Singapore.