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IOL prediction error may be ‘unavoidable,’ despite precise method
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Some errors in IOL power calculation can be avoided with a new formula using simple, direct physical measurement, but an individual prediction error of between 0.5 D and 1 D seems to be unavoidable, a study found.
Paul-Rolf Preussner, MD, PhD, and colleagues at the University Eye Clinic in Mainz, Germany, used a patient cohort of 189 eyes to calibrate the prediction method and then applied the formula to a second cohort of 65 eyes. For more on the formula, called Okulix, click here.
Zero mean prediction errors for IOL position and refraction were obtained without adjusting the parameters and with partial coherence interferometry lengths or ultrasound lengths calibrated relative to the partial coherence interferometry values. Measured mean central IOL position for all IOL types was 4.58 mm. The difference in the individual central IOL position relative to the mean value depended only linearly on axial length, with the mean central IOL position as a free parameter.
To produce zero bias for long and short eyes, the parameter should be 4.6 ± 0.2 mm to obtain zero steepness of the prediction errors, the researchers said.
The study is published in the October issue of Journal of Cataract & Refractive Surgery.