For cataract surgeons leery of presbyopic intraocular lenses (IOLs), the visual results in the FDA study of the investigational Crystalens® HD (Bausch & Lomb, Rochester, NY) might reduce their level of skepticism. A fourth-generation of the Crystalens, the HD-100, features a proprietary change in the optic that is designed to maximize contrast at near without sacrificing the quality of distance and intermediate vision.
The company that brought Crystalens to market in 2003, eyeonics, which was subsequently acquired by Bausch & Lomb, tried to avoid the pitfalls of multifocality (generally some loss of best-corrected visual acuity and contrast sensitivity) by designing an IOL that would move forward in response to ciliary contraction, dynamically increasing the eye’s focusing power. Thanks to the work of Kevin Waltz and others, we now know that, with ciliary muscle contraction, the optic bends or “arches” (as well as the haptics), steepening the lens and increasing its accommodative effect.
My practice is one of 4 US sites where, with my co-investigator Roger Ohanesian, MD, an FDA clinical trial of the HD-100 is being performed. As our group reported at the 2008 American Society of Cataract and Refractive Surgery Symposium in Chicago, investigators performed unilateral implants of the HD-100 in 60 eyes with cataracts. (The contralateral eye was implanted with the third-generation Crystalens.)
It was common for our patients in the trial to say that they liked the vision in the Crystalens-HD eye better than that of the eye implanted with a third-generation Crystalens. One possible reason is greater contrast acuity from the redesigned optic.
Currently, many surgeons who implant Crystalens optimize the patient’s bilateral near acuity by targeting the nondominant eye for about -0.75 D of myopia, slightly diminishing their distance acuity. The results of the HD-100 trial suggest that we are likely to be one step closer to targeting emmetropia in both eyes. This is an exciting development for ophthalmology, one that we hope will move us closer to the day when presbyopic IOL designs will not require patients to sacrifice other aspects of their vision in order to gain functional near acuity.
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