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Abstract :
[en] Purpose
To describe the optical performances of 3 types of diffractive hydrophobic intraocular lenses (IOLs): monofocal achromatic, bifocal and trifocal, using various visible wavelengths.
Methods
3 IOLs were measured with an optical bench (PMTF,LambdaX,Nivelles, Belgium) to determine modulation transfer function (MTF) and point spread function (PSF). Measurements were performed at 480 nm,546 nm,650 nm using an aberration free cornea and aspheric artificial cornea generating +0.28µm positive spherical aberration by ISO11979-2 guidelines. Through-focus MTF was recorded for various pupil apertures. Evaluation of halos was performed from PSF measurements obtained at each focal spot location. Images of USAF targets were recorded with simulated distances from 1m to 25cm. Amplitude of off-axis peaks of radial profile of PSF enabled to quantify percentage of energy within the halos.
Results
The monofocal and the bifocal IOLs presented 2 peaks on the through-focus MTF in green light: intermediate vision (at +1.75D) for the monofocal achromatic lens, and far and near vision (at +4D) for the bifocal IOL of the same material. Three peaks (Distance, Intermediate at +1.75D, Near at +3.5D) were recorded with the trifocal IOL at any wavelength. The achromatic monofocal IOL was monofocal for far vision with red light and monofocal for near vision with blue light. The influence of the cornea models was limited. The amount of halos were comparable between lenses (3 to 5 % of the enclosed central light energy).
Conclusion
The achromatic diffractive IOL behaved like a bifocal IOL with an intermediate addition foci in green light. The bifocal and trifocal IOL induced similar chromatic effects for the near (bifocal, trifocal) and intermediate (trifocal) foci.
