Which of the following instrument is not required to calculate the power of IOL?

Amplitude scan gives Axial length. Keratometer gives corneal curvature. Biometer is used to calculate the power of IOL. Axial length and corneal curvature are substituted in SRK formula for calculation of IOL. Pachymetry is used to calculate thickness of Cornea which is not used in SRK formula for calculation of IOL.