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A. C. Kingston, G. E. Altmann; Depth of Field Comparison Between Aspheric and Spherical Intraocular Lenses. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5729.
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© ARVO (1962-2015); The Authors (2016-present)
The aim of this study is to compare the depth of field for three intraocular lens (IOL) designs in the presence of corneal aberrations, and IOL tilt and decentration. The three IOLs are spherical, negative spherical aberration aspheric, and aberration-free aspheric.
A Monte-Carlo simulation with (100) randomly created eye models was performed to assess IOL depth of field in the presence of corneal aberrations, and tilt and decentration of the IOL. Each IOL was inserted into the same (100) eyes. All three lens designs were evaluated through 3.0 and 5.0mm pupil diameters under photopic lighting conditions. Through-focus image quality was examined for object vergences from -0.75D to +2.00D in 0.25D increments.For each combination of lens design, object vergence, IOL tilt, decentration and set of corneal aberrations, the area under the modulation transfer function (MTF) curve was calculated. The MTF area was used to predict the retinal image quality at each focus position.
For a pupil diameter of 3.0 and 5.0mm, the aberration-free aspheric and spherical IOLs yielded equivalent depth of field. For a 3.0mm pupil the two lens designs also had equivalent image quality at distance. With a 5.0mm pupil diameter, the aberration-free aspheric had a slightly higher MTF peak over the spherical design. At both pupil diameter, the negative spherical aberration aspheric had a smaller depth of field and reduced image quality due to the induced coma caused by tilt and decentration.
Spherical aberration generally helps increase the overall depth of field for a given optical system. The aberration-free lens design has no intrinsic spherical aberration so it does not affect the eye's natural depth of field due to the corneal spherical aberration. Also, an IOL with spherical aberration produces coma when tilted or decentered with respect to the cornea. The coma yields lower MTF values. The aberration-free IOL is less affected by tilt and decentration.The aberration-free and spherical lens designs had equivalent depth of field at a 3.0 and 5.0mm pupil diameter. The aberration-free aspheric had slightly better image quality at distance with a 5.0mm pupil. The negative spherical aberration aspheric had poorer overall image quality and depth of field at both pupil diameters.
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