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To evaluate the accuracy of IOL power calculation in eyes with prior refractive surgery using ray-tracing and the newly described C-constant for the prediction of IOL position

Poster Details

First Author: T.Olsen DENMARK

Co Author(s):    P. Jeppesen              

Abstract Details



Purpose:

To evaluate the accuracy of IOL power calculation in eyes with prior refractive surgery using ray-tracing and the newly described C-constant for the prediction of IOL position.

Setting:

University Eye Clinic

Methods:

A total of 38 consecutive eyes having lens surgery after previous cornea surgery for myopia were studied. The pre-laser refraction ranged from - 6 to - 14 D. All patients had laser biometry (Lenstar) of intraocular distances and Scheimpflug photography (Pentacam) measurement of the Total Refractive Corneal Power taking both the anterior and posterior curvatures of the cornea into account. The IOL power calculation was performed with the Olsen formula using ray tracing and the C-constant concept allowing for unbiased prediction of the IOL position in terms of preoperative anterior chamber depth and lens thickness only.

Results:

The mean numerical prediction error was + 0.05 D (+/- 0.82 D) (+/- SD), range - 1.8 D to + 2.0 D with a mean absolute error of 0.65 D. The mean numerical error was not significantly different from zero. The overall prediction accuracy was 79% within 1 D error.

Conclusions:

Ray tracing and the C-constant concept are promising tools for unbiased IOL power calculation in post-refractive surgery eyes requiring no 'equivalent K-readings' nor systematical off-set corrections. FINANCIAL INTEREST: One of more of the authors... gains financially from product or procedure presented

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