a method for correlating spectacle and intraocular lens prescriptions M.J. Dunn, M.Sc., M.A.A. Santa Barbara, California There ar~ many methods for calculating the power of an mtraocular lens for secondary implantation 1-9, some of which are more complex than others. Generally, intraocular lenses are prescribed according to their dioptric power within the eye. In some cases (e.g.,. Rayner lenses of the Choyce Mark VIII design), the mtraocular lens is described in terms of an equivalent spectacle power needed to correct the aphakia. ~~e re~son for this i~ that many surgeons are more famlhar wIth t?e prescnption of aphakic spectacles than they are WIth the prescription of intraocular lenses. From time to time, the need for a correlation ~ethod has been presented by the ophthalmic profesSlOn. No clear~cut correl~ti?n currently exists, empirical or ~ther~ls~. The dIffICUlty of obtaining such a correlatlOn hes m the fact that two patients with the same sp~ctacle correction may actually require separate mtraocular lens corrections. The influence of the optical constants of the eye varies from patient to patient in a complicated manner. The best that can be expected is an approximate correlation between spec~acle and intraocular lens prescription, by selfconsIstent methods. This article develops such a correlation. Briefly, the method is as follows: A schematic model .is constructed for each of the two aphakic correctlOns, spectacle-corrected and intraocular-Iens~orrected. In each c.ase, the emmetropic prescription IS solved as a functlOn of the schematic variables of the aphakic eye. These variables are then permitted to rang~ over several values, and both the spectacle and the mtraocular lens prescription are calculated for each combination of variables. The prescriptions are then pl.otted together