Intraocular lens (IOL) calculation in very long eyes

Session Details

Session Title: IOL Power Calculations, Post-LASIK & Extreme Eyes

Session Date/Time: Tuesday 25/09/2018 | 14:00-16:00

Paper Time: 15:34

Venue: Room A2

First Author: : P.Preußner GERMANY

Co Author(s): :    P. Hoffmann   J. Wahl                 

Abstract Details

Purpose:

To demonstrate the reason for the (hyperopic) bias in IOL calculation in very long eyes and to show a simple solution how to avoid it.

Setting:

University eye hospital Mainz, Germany, eye clinic Castrop-Rauxel, Germany and eye clinic of the Horst-Schmidt-Klinikum Wiesbaden, Germany

Methods:

93 eyes with uncomplicated cataract surgery, retrospectively selected for axial length >28mm (mean 31.01+-1.66mm, min. 28.29mm, max. 37.56mm) were evaluated. 10 were implanted with AMO Sensar AR40M, 83 with Alcon MA60MA. Prediction errors were calculated with Haigis, SRK/T, Hoffer Q and Holladay I formulas and with OKULIX raytracing.

Results:

For the calculation methods in the said sequence the mean prediction errors are 0.48D, 0.69D, 0.94D, 0.88D and -0.02D for the eyes with an AMO Sensar AR40M, and 0.74D, 0.85D, 1.40D, 1.20D and 0.01D for the eyes with an Alcon MA60MA. But when the assumed ratio of posterior to anterior corneal radii is changed from the Gullstrand to the Liou and Brennan eye model, resulting in a fictitious corneal refractive of 1.327, the mean prediction errors of the formulas are -0.09D, -0.08D, -0.10D and 0.08D for the AMO and 0.15D, 0.05D, 0.32D and 0.37D for the Alcon IOL.

Conclusions:

The choice of a state-of-the-art eye model avoids the underestimation of corneal power and thus the hyperopic outcome in eyes in which an adjustment by a fictitious effective lens position (e.g. A-constant and other so-called formula constants) is not possible because of the negligible impact of the IOL position on the refraction.

Financial Disclosure:

... gains financially from product or procedure presented