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Crystalline lens, aspheric IOL compensate for corneal spherical aberration
J Cataract Refract Surg. 2009;35(3):485-490.
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Aspheric IOLs showed tilt and decentration similar to that of natural young crystalline lenses, with the slight malposition of the IOLs partially compensating for horizontal coma.
“Tilt and decentration of [IOLs] are known to deteriorate image quality, particularly with aspheric IOLs,” the study authors said. They set out to evaulate tilt and decentration of an aspheric IOL and correlate those findings to the position of the crystalline lens in young patients.
The prospective study included 40 eyes of 20 phakic, mildly myopic patients with a mean age of 32 years, and 40 eyes of 20 pseudophakic patients with a mean age of 68 years. The pseudophakic patients underwent cataract surgery and received the Tecnis ZCB00 aspheric IOL (Abbott Medical Optics).
Investigators used Purkinje images to assess lens tilt and decentration, and wavefront analysis to correlate higher-order aberrations with lens malpositioning.
Study data showed crystalline lenses and IOLs had similar tilt and decentration. The IOL patients had a mean total spherical aberration of –0.05 µm. The phakic patients had a mean total spherical aberration of 0.07 µm.
The Tecnis aspheric IOL (AMO) performs as well as the young crystalline lens in terms of correcting spherical aberration and coma. Other studies have shown that the young eye has the best optical performance but decreases with age due to increasing aberrations in the crystalline lens. For the patient, it means we can implant the Tecnis IOL following cataract surgery and the patient can see as well as they did when they were young, if there is no retinal pathology.
– Jack T. Holladay, MD, MSEE
OSN Optics Section Editor