<prompt> Essential parameters for IOL power calculation areKeratometry and axial length of the eyeballKeratometry and corneal thicknessCorneal thickness and axial length of the eyeballCorneal thickness and anterior chamber depth  <response>: 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 