Back to Freepaper Session

Accuracy of intraocular lens calculations in patients with high myopia

Session Details

Session Title: Cataract II

Session Date/Time: Saturday 15/02/2014 | 08:30-11:00

Paper Time: 09:50

Venue: Gallus Hall (Level -1)

First Author: : AnnaOrlicka-Mosiej POLAND

Co Author(s): :    Ewa Mrukwa-Kominek              

Abstract Details

Purpose:

The aim of this study was to analyze the accuracy of intraocular lens power calculations in patients with high myopia. In the calculations by Hoffer Q, Holladay 1, SRK/T, Haigis formulas was assessed the accuracy, predictability, and a tendency to postoperative hyperopic shift. The study also aimed to determine whether a correlation exists between axial length and postoperative refractive outcome and to determine the need for optimization of the lens constants separately for positive et negative lenses

Setting:

Department of Ophthalmology Silesian University of Medicine, Independant University Hospital Ceglana, Kaowice, ul Ceglana 35; 40-952 Katowice

Methods:

The research was based on 120 eyes of 104 patients with cataract and high myopia. Patients were divided into three groups according to the axial length measured before the operation, and into two groups depending on the type of the implanted intraocular lens. All patients underwent uncomplicated standard phacoemulsification with in-the –bag IOL implantation. The whole group was implanted with nine different IOLs. The calculation was performed in the IOL Master calculation software. The IOL power was calculated using the SRK/T formula. The lens constants are optimized and used in the calculations for all lenses except AR40M for which the constants AR40 E were used. Precision of calculations by Hoffer Q, Holladay 1, SRK/T, Haigis formulas compared on the basis of the absolute value of the difference in spherical equivalent refraction predicted and the actual, obtained 6 weeks after surgery. This value is defined as the mean absolute error (MAE). The mean difference in spherical equivalent refraction of predicted and actual, expressed as the mean error (ME) was calculated to show the tendency to overcorrection or undercorrection in the formulas

Results:

In the whole group the Haigis formula produced the lowest MAE, while the ME for all formulas was negative, except for the Haigis formula where this value was positive. In the group of patients with the eye length from 26.0 to 27.99 mm and from 28.0 to 29.99 mm the Haigis and SRK/T formulas produced the lowest MAE and ME only for them have been positive. In patients with the eye length above 30 mm, the Haigis formula produced the lowest MAE, while the ME for the calculations by all formulas were negative. In both groups of patients who were implanted lenses of the positive and negative (AR40M and MA60MA) the Haigis formula produced the lowest MAE, while the ME for the calculations by all formulas was negative for the AR40M and positive for the MA60MA

Conclusions:

In the whole group of patients with the eye length above 26 mm the most useful formula for IOL power calculations is the fourth-generation Haigis formula. The most useful formula for IOL power calculations in the group of patients with the eye length from 26.0 to 27.99 mm and from 28.0 to 29.99 mm is a third generation SRK/T formula and the fourth generation Haigis formula, while in patients with the eye length above 30 mm Haigis formula. For all 4 tested formulas, the longer the eye, the lower the accuracy of the calculations, and the greater the tendency to postoperative hyperopic shift. Optimization of the lens constants separately for eyes with positive and negative lenses helped to avoid postoperative hyperopic refractive error FINANCIAL INTEREST: NONE