The optical performance of new multifocal intraocular lens designs is frequently assessed using the modulation transfer function (MTF). We discuss the relationship between the MTF and clinical measures of human visual function, such as threshold visual acuity and contrast sensitivity. Using in vitro MTF measurements of a human eye model containing a multifocal or monofocal intraocular lens, we predict relative changes in acuity and contrast sensitivity and outline the techniques using a simple model of human retinal threshold detection. Specific concepts introduced include the visual acuity graph, predicted visual acuity graph, and predicted contrast sensitivity function.