HM-ZL Formula Calculator

An IOL power calculation formula for highly myopic eyes

Required Measurements
Please select a K Index.
mm
AL must be between 26 and 40 mm.
mm
ACD must be between 1.25 and 5.25 mm.
D
K1 must be between 30 and 60 D.
D
K2 must be between 30 and 60 D.
A Constant must be between 80 and 150.
D
Target refraction must be between -99 and 99 D.
a0 must be between -99 and 99.
a1 must be between -99 and 99.
a2 must be between -99 and 99.
years
mm
Will be calculated automatically if left empty
mm
Will be calculated automatically if left empty
About the HM-ZL Formula

The HM-ZL formula is a novel artificial intelligence-based formula for highly myopic eyes (axial length over 26.00 mm) developed by Zhu and Lu. The formula uses machine learning to provide accurate IOL power predictions for challenging cases.

Instructions

The HM-ZL formula requires compulsory information input of axial length, anterior chamber depth, flattest and steepest K values (namely the K1 and K2), A-constant, a0, a1, and a2 constants. Lens thickness (LT) and white to white distance (WTW) are now optional - if not provided, they will be automatically imputed using regression models trained on our dataset.

We recommend using the constants from the ULIB website (http://ocusoft.de/ulib/). A default refractive index of 1.3375 has been selected. If your device uses a different refractive index, please select the appropriate option from the drop-down menu.

The training dataset has updated to 31 Dec 2021; we will continue to include new data to improve the performance of the Zhu-Lu formula. If you have any questions or suggestions or want further information about the HM-ZL formula, please contact us at HM_ZLF@163.com.