Intraocular lens power calculations for multifocal intraocular lenses.
We performed calculations for anterior and posterior chamber intraocular lenses, determining the necessary power for emmetropia and 3 diopters of myopia for various axial lengths and corneal powers. Our results demonstrate that to achieve an effective add of 3.00 diopters at the spectacle plane (reading distance of 33 cm), the fabricated add (labeled add) on an intraocular lens must vary from 3.3 diopters for an anterior chamber lens in a patient with a flat cornea, to 5.1 diopters for a posterior chamber lens in a patient with a steep cornea. For most patients, targeting for an effective add of 3 diopters is appropriate, but factors such as availability of fabricated adds from the manufacturer and unusual patient requirements for near vision, may alter this target. We reviewed alternatives with monofocal lenses, such as monovision and compound myopic astigmatism.