I present a simplified equation to calculate the iseikonic intraocular
lens power and the resultant refractive error needed to achieve iseik
onia with 5% tolerance limits. Iseikonic lens power calculations are i
ndicated in the presence of a unilateral cataract and a phakic fellow
eye. Iseikonia is often achieved by leaving the operated eye more myop
ic than the fellow eye. The induced myopia, with 5% tolerance limits,
ranges from -0.75 +/- 2.75 diopters (D) for a posterior chamber lens t
o -2.40 +/- 2.75 D for an anterior chamber lens.