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P. Rosales, I. Jiménez–Alfaro, L. Llorente, S. Marcos; Complete Eye Models Predict Wave Aberrations in Post–Cataract Eyes . Invest. Ophthalmol. Vis. Sci. 2006;47(13):313.
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© ARVO (1962-2015); The Authors (2016-present)
To compare experimental wave aberrations in eyes implanted with intraocular lenses (IOLs) with predictions from computer model eyes using individual information of corneal topography, ocular biometry, lens geometry, tilt and decentration.
The study was performed on 16 eyes from 10 patients implanted with aspheric IOLs. Ocular aberrations were measured using a custom–built laser ray tracing system. Maximum pupil size ranged from 4.5 to 6 mm. Corneal topography was measured using videokeratoscopy, anterior chamber depth and axial length were measured using optical biometry. The lens geometry was provided by the manufacturer, and IOL tilt and decentration were measured using a custom–developed Purkinje imaging system. Computer eye models were programmed for each eye on an optical design program (Zemax). Wave aberrations were predicted using the values of IOL tilt and decentration for each eye as well as setting them to zero. The RMS of a difference map (predicted minus the measured wave aberration) was used as metric of the goodness of the prediction (RMS_diff).
1) Corneal aberrations were higher than total measured wave aberrations, although in most cases total wave aberrations were dominated by corneal aberrations 2) The experimental internal wave aberrations were dominated by negative spherical aberration, although in some cases other higher order aberrations were present. 3) Average RMS_diff was 0.61 µm. RMS_diff was lower when including tilt and decentration in 13 out of 16 eyes. When real tilt and decentration were not included RMS_diff increased by 10% (and 30% for coma and spherical aberration only). 4) Measured internal aberration was 0.39 µm, predicted internal aberration with measured tilt/decentration was 0.25 µm and predicted internal aberration with no tilt and decentration was 0.17 µm, indicating that the presence of tilt and decentration increases internal aberrations, and suggesting the presence of additional sources of internal aberrations.
Computer eye models with individual biometric data predict most of the features of wave aberrations measured in eyes with IOLs. The prediction improves when incorporating real estimates of IOL tilt and decentration. Anterior corneal surface non–rotationally aberrations are the major source of aberrations. Slight discrepancies may occur by contributions of posterior cornea or lens flexure.
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