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Tecnis lens data support efficacy of aspheric IOLs
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MADRID, Spain — Studies showed the Tecnis aspheric lens restores vision and increases contrast sensitivity if implanted correctly, surgeons here said during a symposium at the Congress of the European Society of Ophthalmology.
Though the Tecnis lens (Pfizer) could reduce the depth of vision in eyes, one study showed that it corrects the spherical aberration typically present in older eyes and increases visual performance without compromising depth of focus, said Pablo Artal, MD, PhD.
Dr. Artal used wavefront technology to observe the effects of aberrations with customized IOLs. Like the young eye, aspheric lenses have a negative aberration, which compensates for corneal aberrations and increases contrast sensitivity, he explained.
The lens modifies the anterior surface with a lower lens power, which produces a crisper image, said Jack Holladay, MD. It creates negative spherical aberrations to compensate for the cornea.
Success with the lens, however, depends on precise implantation, Dr. Holladay said. First, the lens must be centered within 0.5 mm. The lens must be centered 0.15, 0.30 and 0.28 mm and must be tilted less than 7º. If implanted off-center, it may not perform properly, he said. It can be implanted upside-down with no affect on performance but would induce 1.37 D of myopia.
When compared to conventional silicone and acrylic lenses, contrast sensitivity was significantly better. There was only a slight difference in visual acuity, said both Roberto Bellucci, MD, and Mark Packer, MD.