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S.D. McLeod, V. Portney, L.G. Vargas; Magnification Induced by Single Optic Intraocular Lenses Compared to a Dual Optic Accommodative Intraocular Lens Design . Invest. Ophthalmol. Vis. Sci. 2006;47(13):301.
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© ARVO (1962-2015); The Authors (2016-present)
The conjugation power of accommodative intraocular lens (IOL) systems based on the principle of forward optic axial displacement can be increased by a dual lens arrangement with a high plus power front optic coupled to an emmetropizing minus posterior optic. However, this arrangement that suggests a Galilean telescope might be associated with unwanted magnification. The purpose of this study was to compare image–object magnification produced by the dual optic arrangement versus a standard single optic IOL for a given pseudophakic eye configuration.
In a model eye optical system, a dual optic lens system based on the power assignment of the Visiogen Synchrony lens and a typical biconvex IOL located at physiological positions of 4.0 mm and 5.0 mm posterior to the inner surface of the cornea were analyzed in eyes with different axial lengths: short (22.2 mm), medium (23.25 mm) and long (25.5 mm). In order to produce the maximum possible optical magnification, separation between the anterior and posterior optics of the dual optic IOL was set at 1.5 mm. The corresponding lens configuration resulted in a near object position of approximately 4 D of vergence. The image–object magnifications were determined by an eye optical system coordinate transformation where the refraction surfaces were specified by the corresponding refraction matrices and interspaces between the surfaces by the translation matrices. The image–object magnifications for the same eye configuration were then compared between the ocular systems with the dual optic IOL and a conventional single optic IOL.
The image–object magnifications with the dual optic IOL varied from –0.0580 for a short eye, to –0.0727 for a long eye. In eyes with standard biconvex IOLs, the calculated image–object magnifications ranged from –0.0575 in short eyes to –0.0709 in the long eye. The magnification difference between the dual optic IOL and a typical biconvex IOL was 1% for a short eye, 2.2% for a medium length eye and 2.5% for a long eye.
In a theoretical eye optical system, the dual optic IOL modeled did not show significant magnification effects when compared with a typical biconvex IOL. This suggests that any improved visual function with the dual lens arrangement would not be attributable simply to magnification effects, and that this system is not expected to produce aniseikonia even if the fellow eye remains phakic or is corrected with a standard single optic intraocular lens.
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