Essential parameters for IOL power calculation are
Keratometry and axial length of the eyeball
Keratometry and corneal thickness
Corneal thickness and axial length of the eyeball
Corneal thickness and anterior chamber depth
Calculation of IOL power (Biometry) : The most common method of determining IOL power uses a regression formula called 'SRK (Sanders, Retzlaff and Kraff) formula'. The formula is P = A - 2.5L - 0.9K where: P is the power of IOL, A is a constant which is specific for each lens type. L is the axial length of the eyeball in mm, which is determined by A-scan ultrasonography. K is average corneal curvature, which is determined by keratometry. The ultrasound machine equipped with A-scan and IOL power calculation software is called 'Biometer&;. Ref:- A K KHURANA; pg num:-196
Lens