<prompt> To check power of IOL, which formula is commonly used: March 2010Hoffer formulaHolladay formulaSRK formulaNone of the above  <response>: Ans. C: SRK formula Sanders-Retzlaff-Kraff SRK formula is the widely used formula for calculating the power of the intraocular lens to be implanted. It is based on a statistical correlation between calculated and observed refractive error after intraocular implantation. 