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PA Piers, U Mester, N Anterist, P Dillinger, S Norrby; How Wavefront-Based IOL Designs affect Pseudophakic Visual Quality . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2022.
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Purpose: To examine the relationship between ocular wavefront aberration, MTF and visual quality in eyes implanted with IOLs with two different optical designs. Methods: Thirty bi-lateral cataract patients were implanted with IOLs made from high refractive index silicone. Each patient received one conventional IOL, with positive spherical aberration, and one with negative spherical aberration (Pharmacia model Tecnis Z9000). The Z9000 was designed to balance the corneal spherical aberration measured in a cataract population. In order to assess visual quality, contrast sensitivity was measured using sine-wave grating targets under mesopic lighting conditions (6 cd/m2). Postoperative ocular and corneal wavefront aberration measurements were performed using a Hartmann-Shack wavefront sensor and a Zeiss Humphrey corneal topographer. Postoperative ocular MTF was calculated from the measured wavefront aberrations. Results: The Z9000 lens effectively compensates for the corneal spherical aberration and thus significantly reduces ocular wavefront aberration in pseudophakic eyes. The postoperative ocular wavefront aberration of the two populations (Z9000 eyes and eyes with conventional IOLs) differs only in the spherical aberration component. Contrast sensitivity at 6 c/deg is improved as a result of this decrease in ocular wavefront aberration. The magnitude of this improvement can be predicted using both the MTF calculated from the postoperative ocular wavefront aberration and the MTF predicted using a physiological eye model and ray tracing techniques. Conclusions: The correlation between ocular wavefront aberration and contrast sensitivity reveals the measurement of ocular and corneal wavefront aberration to be a valuable tool for IOL design.
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