EVALUATION OF BARRETT UNIVERSAL II, SRK-T AND HAIGIS FORMULAE FOR INTRA-OCULAR LENS POWER CALCULATION IN HIGHLY MYOPIC EYES USING OPTICAL BIOMETRY

To assess and compare the accuracy of Barrett Universal II, SRK-T and  Haigis formulae  for intraocular lens power calculation in high myopic eyes, using optical biometry.

Cairo University Hospitals,Cairo,Egypt.

This is a prospective, interventional study included 34 eyes  with axial length ≥ 26 mm of 34 patients ,who underwent uneventful phacoemulsification with implantation of one piece IOL in the bag aiming for – 1 diopter postoperative refraction after one month. The refractive prediction error (RPE) was calculated for each formula by subtracting the predicted refraction from the actual refraction postoperatively. The mean numerical error (MNE) and median absolute error (MedAE) were determined for each formula and compared.

The Barrett Universal II formula produced the lowest MNE

 (-0.11 D) close to zero and lowering the percentage to 44.1 % of eyes would have hyperopic outcomes. Furthermore, Barrett U II formula had the lowest MedAE (0.15 D; MAE of 0.45) followed by Haigis and SRK/T (0.40; MAE of 0.64 and 0.47; MAE of 0.63 respectively). There was a significant difference between Barrett Universal II and the two other formulae even when compared separately. Also, it met the benchmark criteria for postoperative refraction results as the percentage of eyes within ±0.50 D was 82.4 % which was statistically significant higher than the other two formulae.

Conclusion: The Barrett U

The Barrett Universal II formula reduced the percentage of hyperopic outcomes in eyes with high axial myopia. In addition, it had the most accurate predicted refraction for minus and low powered IOL.