Clinical evaluation of six intraocular lens calculation formulas.

We examined the results of posterior chamber intraocular lens (IOL) implantation and evaluated six commonly used IOL power calculation formulas (original Binkhorst, modified Binkhorst, Colenbrander, Shammas, Hoffer, and SRK regression) to determine which ones produce the most accurate and predictable results. We found that the accuracy of the various formulas depends upon several factors, including the surgeon's technique, the type and style of posterior chamber IOL implanted, and the axial length of the eye being operated on. Furthermore, we found that the results using the different formulas vary in a consistent pattern. Surgeons must therefore evaluate their cases periodically to determine which formulas and IOL styles will provide their patients with the most accurate and satisfying results.