A slide rule for calculating the power of an intraocular lens.

We have designed a slide rule to calculate the emmetropizing and iseikonizing power of an intraocular lens (IOL). Like the dial biometer currently used for these calculations, the slide rule is inexpensive, easy to use, simple, and a compact pocket size. It can, however, also be used to calculate postoperative refractive error, corneal power when various keratometers are used, and conversion of refractive correction at the spectacle frame to that at the cornea, or vice versa. All the calculated data are within the accuracy suitable for clinical work.