Extreme myopia: IOL power calculation using recent formulas

Session Details

Session Title: Cataract
Session Date/Time: Friday 21/02/2020 | 10:30-13:00
Paper Time: 10:54
Venue: Fes 1.

First Author: M.Raimundo PORTUGAL
Co Author(s): J. Bernardes  C. Lobo  J. Murta           

Abstract Details

Purpose:

To comparatively evaluate the accuracy of newer intraocular lens (IOL) calculation formulas (Barrett Universal II, Kane, Ladas and Hill-RBF 2.0) and common established formulas (SRK/T and Holladay 1) after Wang-Koch (WK) adjustment in the prediction of postoperative refraction in extreme myopic eyes.

Setting:

Two clinical sites: (1) tertiary public hospital, Centro Hospitalar e Universitário de Coimbra (CHUC), Coimbra, Portugal; (2) private practice, Unidade de Oftalmologia de Coimbra (UOC), IDEALMED, Coimbra, Portugal.

Methods:

Retrospective study including 82 eyes with high myopia submitted to uncomplicated cataract surgery with implantation of an AcrySof MA60MA IOL (power range -5.00 to +5.00 diopters). All patients underwent optical biometry (Carl Zeiss IOLMaster 500 and IOLMaster 700, and Allegro Biograph) and the post-operative spherical equivalent for the same implanted IOL was estimated using SRK/T, Holladay 1, Barret Universal II, Kane, Ladas and Hill-RBF 2.0 formulas.  Outcomes included median absolute prediction error (MedAE) and the proportion of eyes within 0.25, 0.50 and 1.00 diopters (D) of this prediction.

Results:

The mean axial-length was 30.89 ± 1.85 mm. Fifty-eight eyes had a positive-diopter IOL implanted, fifteen eyes a negative-diopter and nine eyes a zero-diopter IOL. The mean post operatively spherical equivalent was -0.45 ± 0.79D.  The MedAE in order of lowest to highest was Hill-RBF 2.0 (0.31), Kane (0.33), Barrett (0.36), Holladay Iwk (0.37), SKR/Twk (0.37), SRK/TULIB (0.43), and Ladas (0.61). Hill-RBF yielded a prediction error within 0.25D, 0.50D and 1D of 43.1%, 70.6% and 94.1%, respectively, whereas Ladas yielded a prediction error within 0.25D, 0.50D and 1D of 15.2%, 38% and 81% of the eyes.

Conclusions:

Myopic eyes are a complex and singular subgroup in terms of IOL power calculation. Nonetheless, newer formulas like Barrett Universal II, Kane, Hill-RBF v2.0, SRK/Twk and Holladay Iwk showed that reasonably accurate outcomes are possible, with formulas reaching a prediction error percentage within ± 0.50D as high as 70.6%. Hill-RBF v2.0 showed the most consistent performance along the AL range with a global MedAE of 0.32D.

Financial Disclosure:

... receives consulting fees, retainer, or contract payments from a company producing, developing or supplying the product or procedure presented