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Hiroki Tanaka, Yu Kato, Takako Tachikawa, Osamu Katsumi, Kazuhiko Ohnuma, Toru Noda; Evaluation of Wavefront Aberrations Induced by Dislocation of Toric and Aspheric Intraocular Lenses and the Effects on Simulated Retinal Images. Invest. Ophthalmol. Vis. Sci. 2012;53(14):1377.
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© ARVO (1962-2015); The Authors (2016-present)
To calculate the wavefront aberrations induced by dislocation of toric and aspheric intraocular lenses (IOLs) and evaluate the effect on the retinal images.
Wavefront aberrations were calculated using optical calculation software (ZemaxTM) in a simulated model eye (corneal refractive power, 42.0 diopter [D]; corneal astigmatism [CA], 3 D; pupil diameter, 4.0 mm) in which two toric IOL models (spherical equivalent [SE] power, 20 D; astigmatism, 3 D at the corneal surface) with different spherical aberrations (SAs) (0 and -0.27 micrometer) were placed. When the IOL positions were shifted 0 to 0.5 mm in the X, Y, and Z directions and rotated around the optical axis (0-10 degrees), the EFFECTS? were calculated. The retinal images were simulated by a convolution procedure of the point spread functions according to the calculated wavefront aberration data in each condition and various sizes of Landolt’s rings.
The correctly positioned toric IOL with minus SA produced better quality retinal images and less SA than the IOL with null SA. Rotation of both toric IOLs caused residual astigmatism and concomitantly higher order aberrations, but the amount of the latter was below the level that would substantially affect the retinal images. Shifts in the X-Y directions increased the prism effect, Z(1,-1), Z(1,+1); the minus value of the SE, Z(2,0); astigmatism, (Z2,-2, Z2,+2); and coma (Z3,-1, Z3.+1), which caused retinal image degradation. The changes in aberrations and the effects on the retinal images were marked in toric IOL with minus SA and minimal in toric IOL with null SA. Shifts in the Z direction changed the SE, astigmatism, and SA values in both toric IOLs.
The toric IOL with minus SA to compensate for CA and the SA positioned correctly produced better retinal images because of less SA, but if dislocated, the amounts of induced astigmatism and coma are greater with more retinal image degradation compared with the IOL with null SA.
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