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H. Zuluaga, S. O. Luque, F. Diaz Douton, M. Aldaba, M. Arjona, J. Pujol; Defocus Curve of Multifocal Intraocular Lenses Measured With a New Asymmetric Focus Double Pass System. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5743.
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© ARVO (1962-2015); The Authors (2016-present)
It is of great interest the measurement of the defocus curve in multifocal intraocular lenses (MIOL’s) that influence the success in the adaptation to this correction. The aim of this work was to develop a novel objective system for measuring the defocus curve of MIOL’s that can be used in vitro and in vivo conditions. It is based in a double pass system (DP) with independent first and second pass focus control.
The developed system permits to control independently the focus correction for the first and second pass by means of two different Badals. Symmetric and asymmetric pupil configuration can be used. The employed wavelength was 780nm. The best far vision correction was obtained by changing simultaneously both Badal systems. Intermediate and near vision were measured by moving only the second pass Badal. DP images were recorded while increasing defocus from far vision, in steps of 0.25D, up to 4D. The defocus curve was determined by extracting the FWHM from each of DP images. Measurements were performed in vitro using an artificial eye in three different designs of MIOL’s: A refractive (Amo NGX1), a diffractive (AcrySof ReSTOR SN60D3) and an aspheric diffractive (AcrySof ReSTOR SN6AD3). Entrance pupil diameter was 2mm and exit pupil diameters were 2mm and 4mm.
The measured addition was the difference of the two peaks showed by the defocus curve. The difference found with the announced by the manufacturer was less than 0.5D for the three measured lenses. The dependence of refractive MIOL with pupil size was observed while diffractives lenses showed similar behaviours for 2-2 and 2-4 pupil sizes.
A new robust and objective optical method to measure defocus curve of MIOLs has been developed. It is based on the DP image evaluation along different focuses of the MIOL and it has been applied for in vitro measurements of three different lens designs. This technique also could be applied in vivo for testing objectively the optical behaviour of intraocular lenses.
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