My name is Dr. Thomas Kohnen. I am Professor and Chair of the Department of Ophthalmology at Goethe University, where I specialize in cataract and refractive surgery. Presbyopia mitigating intraocular lenses use a variety of optical designs to create multiple points of focus or an extended focal range, with the goal of providing patients with good vision from near to distance. Selecting the right IOL for a patient’s individual needs is essential to their overall satisfaction, so it is important to understand the relative strengths of different designs. My colleagues and I conducted an Alcon-initiated bench study to simulate the halos produced by presbyopia mitigating IOLs with different optical designs. In our Alcon-initiated study, we used a bench setup to measure the halos produced by each IOL when presented with simulated vehicle headlights. Test IOLs were mounted in a model eye with matched corneal spherical aberration and an external pupil scaled to 4.5 mm. We measured halos produced by the IOLs using a pinhole target simulating a 100 mm diameter headlight at 30 m, using a 4x microscope objective. Using the collected images, we assessed halo size and intensity by calculating the area under the curve of light intensity plotted versus visual angle up to 3 degrees. Under these experimental conditions, we observed a range of results for the various presbyopia mitigating and monofocal IOLs. In general, the IOLs with a non-diffractive optical design produced less pronounced halos under simulated bench conditions than the diffractive IOLs. In addition, the variation in simulated bench halos across diffractive designs were relatively wide. Further studies will be needed to understand how these observations translate to the patient experience, but our results do provide important evidence that should be weighed by surgeons when choosing an IOL.
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