Purpose
The aim of this study was to compare the predictability of different intraocular lens (IOL) power calculation formulas [Sanders–Retzlaff–Kraff (SRK) II formula, SRK-T formula, Haigis formula, Hoffer formula] in axial hyperopic patients [axial length (AL) <22 mm] undergoing cataract surgery using IOL master.
Patients and methods
This study comprised 40 eyes of 26 patients who presented with cataract and axial eye length less than 22 mm. Before phacoemulsification and IOL implantation, AL measurement, keratometry measurement and anterior chamber depth measurement using the IOL master were done. IOL power was calculated using four different formulas (SRK-II, SRK-T, Haigis, Hoffer ). Actual stabilized postoperative refraction (spherical equivalent) 1 month after surgery was measured and the accuracy of the four different formulas was compared. Differences between actual postoperative refraction and predicted refraction using the different formulas were analyzed. value less than or equal to 0.05 was considered statistically significant. Furthermore, the percentage of eyes with mean absolute prediction error (MAE) within ±0.5 and ±1.0 diopter (D) for each formula was estimated, as well as the correlation coefficient () between the AL and MAE for each formula.
Results
There was a significant difference between the MAE of the four formulas, except there was no significant difference between the MAE of SRK-T and SRK-II. The Haigis formula had a smallest MAE of 0.47±0.36 D, then Hoffer with a MAE of 0.87±0.51 D, and then SRK-T with a MAE of 1.38±0.89 D. The SRK-II had the largest MAE of 1.70±1.06 D. The Haigis formula predicted more eyes with MAE within ±0.5 and ±1.0 D of the predicted spherical equivalent compared with other formulas. The correlation between AL and AE has shown a negative value and value of less than 0.05 for all formulas.
Conclusion
The Haigis formula provides more accurate results concerning the postoperative target of refraction in eyes with an AL of less than 22.0 mm. Hoffer could be also used as an alternative.