Intraocular lens power calculation for eyes with high and low average keratometry readings: a comparison between various formulas

Session Details

Session Title: IOL Power Calculations

Session Date/Time: Sunday 11/09/2016 | 16:00-18:00

Paper Time: 17:26

Venue: Hall C2

First Author: : O.Reitblat ISRAEL

Co Author(s): :    A. Levy   G. Kleinmann   A. Abulafia   E. Assia           

Abstract Details

Purpose:

To compare the accuracy of different intraocular lens (IOL) power calculation formulas for eyes with average keratometry (k) readings greater than 46.00 diopters (D) and lower than 42.00D.

Setting:

Ein-Tal Eye Center, Tel-Aviv, Israel

Methods:

Consecutive cases of eyes having cataract extraction surgery with steep and flat preoperative corneal curvatures (K>46.00D and K<42.00D, respectively) with the Lenstar-LS900 device were enrolled. Refractive prediction errors for the Barrett Universal II, Haigis, Hoffer Q, Holladay 1, Olsen and SRK/T formulas were compared. Optimized K values for the SRK/T formula were back-calculated for each group. Validation was performed using an additional data set.

Results:

102 eyes (54, K>46.00D; 48, K<42.00D) were evaluated. For K readings over 46.00D, a myopic error was noted in calculations with the SRK/T formula (-0.33D, p<0.001) and a hyperopic error using the Olsen’s C-constant (0.23D, p<0.001). The percentage of eyes with an absolute error of ≤0.50D ranged from 59.35% (SRK/T) to 79.63% (Olsen A-constant). For corneas with a dioptric power below 42.00D, myopic errors were seen using the Hoffer Q, Haigis and Olsen-C formulas (-0.32D, p=0.015, -0.28D, p<0.001 and -0.10D, p=0.049, respectively) and a hyperopic error using the SRK/T formula (0.18D, p<0.001). The refractive prediction within ±0.50D ranged between 72.92% (Hoffer Q) and 100% (Barrett Universal II).

Conclusions:

IOL power calculation for eyes with flat and steep corneas requires the use of specific formulas for accurate postoperative refraction. An adjustment equation for optimized K values with SRK/T formulas is proposed.

Financial Disclosure:

NONE