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Effect of corneal aberrations on intraocular lens power calculations


PURPOSE: To use ray tracing to determine the influence of corneal aberrations on the prediction of the optimum intraocular lens (IOL) power for implantation in normal eyes and eyes with previous laser in situ keratomileusis (LASIK).

SETTING: Hospital Universitario Virgen de la Arrixaca, Murcia, Spain.

DESIGN: Case series.

METHODS: The optimum IOL power was calculated by ray tracing using a patient-customized eye model in cataract surgery cases. The calculation can be performed with or without inclusion of the patient’s corneal aberrations. Standard predictions were also  generated using current state-of-theart IOL power calculation techniques. The results for all predictions were compared with the
optimum IOL power after cataract surgery.
RESULTS: For patients without previous LASIK (n Z 18), the standard approaches and the ray-tracing procedure gave a similar  mean absolute residual error and variance. The incorporation of corneal aberrations did not improve the accuracy of the ray-tracing prediction in these cases. For post-LASIK patients (n Z 10), the ray-tracing prediction incorporating corneal aberrations generated the most accurate results. The difference between the prediction with and without considering corneal aberrations correlated with the amount of corneal spherical aberration (r2 Z 0.82), resulting in a difference of up to 3.00 diopters in IOL power in some cases.

CONCLUSIONS: Ray tracing using patient-customized eye models was a robust procedure for IOL power calculation. The   incorporation of corneal aberrations is crucial in post-LASIK eyes, primarily because of the elevated corneal spherical aberration.
Financial Disclosure: Mrs. Canovas and Dr. Artal hold a provisional patent application on the ray-tracing procedure. Mrs. Canovas is an employee of Abbott Medical Optics Groningen B.V. No other author has a financial or proprietary interest in any material or  method mentioned

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