Comparison of different formulas for intraocular lens power calculation using a new optical biometer

To evaluate and compare the predictability of different formulas for intraocular lens (IOL) power calculation using a new optical biometer (Aladdin).

This prospective cross-sectional study included 70 eyes of 70 patients who underwent uneventful phacoemulsification with IOL implantation. Preoperative IOL power calculations were performed using the Aladdin optical biometer. Postoperative actual refractive errors and errors predicted by the SRK/T, SRK II, Holladay 1, Hoffer Q and Haigis formulas were analyzed. The mean estimation error (EE), mean absolute estimation error (AEE) and the percentage of eyes within ± 0.50 and ± 1.00 D of the target refraction for each of five formulas were calculated and compared. This analysis was also repeated in three groups formed based on axial length (AL) (group 1: <22.5mm, group 2: 22.5-24 mm, group 3: >24 mm).

In the overall study group, the smallest mean AEE was provided by the Holladay 1 formula, however there was no statistically significant difference in the mean AEE's predicted by the five formulas (P=0.34). The highest percentage of eyes within ± 0.50 and ± 1.00 D of the target refraction was also found by using Holladay 1 (71% and 97%). SRK/T provided smallest mean AEE for groups 1 (n=13) and 3 (n=16). In group 2 (n=41), the smallest mean AEE was obtained using Holladay 1.

Based on the Aladdin biometric data used in our study, better results can be obtained using SRK/T formula in eyes with short or long AL. The Holladay 1 formula may be preferred in eyes with moderate AL.