New-approach formula for IOL power calculation in keratoconus

Session Details

Session Title: Presented Poster Session: Cataract Surgery Special Cases

Venue: Poster Village: Pod 1

First Author: : V.Camps SPAIN

Co Author(s): :    V. Mateo   R. Fikry Riad   E. Caravaca-Arens   F. Labib   M. Caballero   D. Piñero        

Abstract Details

Purpose:

To obtain an expression of the adjusted IOL power (PIOLadj) in keratoconus eyes associated to minimal errors in IOL power calculation.

Setting:

University of Alicante (Spain)

Methods:

The following IOLs were implanted: Acrysof IQ Toric, Acrysof SA60AT in 9 eyes, Sensar in 3 eyes, Tecnis 1 in 4 eyes and Tecnis Toric in 2 eyes. The PIOLadj is based in Gauss equations, using and adjusted keratometric index (nkadj) specific for keratoconus eyes. From this nkadj, an adjusted keratometric corneal power is calculated (Pkadj). The PIOLadj calculation was performed after estimating the ELP (effective lens position) using a mathematical expression obtained by multiple regression analysis (named ELPadj). Comparison between the PIOLadj and the real intraocular power implanted in each patient (PIOLreal) was carried out.

Results:

This retrospective study included a total of 25 eyes of 25 patients with ages ranging from 20 to 76 years old. No significant differences between PIOLreal and PIOLadj were found. However, differences could be clinically relevant up to of 2.54 D as PIOLreal increases. But, in the range of PIOLreal between 0 and 20 D, differences were lower than 1.5 D, being most of them below 1 D.

Conclusions:

A new formula of IOL power calculation (PLIOadj) based on the use of an adjusted keratometric power (Pkadj) that consider a variable keratometric index due to the influence of the posterior corneal surface (nkadj) and adjusted effective lens position (ELPadj) is useful for estimating IOL power in low to moderate keratoconus, with more limitation in the most advanced keratoconus. Financial disclosure: The authors have no proprietary or commercial interest in the medical devices that are involved in this manuscript.

Financial Disclosure:

None