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Ray tracing yields more accurate IOL power calculations in post-LASIK patients
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Ray tracing used to measure corneal aberrations was effective in making IOL power calculations in eyes with or without previous refractive surgery, a study found.
“The incorporation of corneal spherical aberration is crucial for the accurate prediction of the IOL power in eyes that have had refractive surgery,” the study authors said.
The study included 10 patients who had undergone previous LASIK and 18 patients who had not had LASIK. All patients underwent small-incision cataract surgery and implantation of a Tecnis ZA9003 aspheric monofocal IOL (Abbott Medical Optics).
Ray tracing using a patient-customized eye model was used to calculate optimum IOL power.
“The calculation can be performed with or without inclusion of the patient’s corneal aberrations,” the authors said.
Standard IOL power calculation techniques were used to generate standard predictions. Investigators compared predicted IOL power calculations with optimum IOL power.
In patients without previous LASIK, study data showed that standard calculation techniques and ray tracing resulted in similar mean absolute residual error and variance. The inclusion of corneal aberrations did not result in more accurate ray tracing prediction.
The maximum difference between ray tracing predictions was 0.5 D.
In patients with previous LASIK, the ray tracing technique using corneal aberrations produced more reliable power predictions compared with standard methods.
“The difference between the prediction with and without considering corneal aberrations correlated with the amount of corneal spherical aberration, resulting in a difference of up to 3 D in IOL power in some cases,” the authors said.
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