ACCURACY IN DETERMINING INTRAOCULAR-LENS DIOPTRIC POWER ASSESSED BY INTERLABORATORY TESTS

Purpose: To describe a testing program conducted by a standards group as a guide for setting international tolerances for intraocular lens ( IOL) dioptric power. Setting: Multicenter study. Methods: Seven biconv ex, poly(methyl methacrylate) IOLs ranging in power from 10.00 through 30.00 diopters (D) were circulated among nine participating laborator ies experienced in IOL optical measurements. Each laboratory performed repeated optical tests to determine dioptric power. These results wer e analyzed for repeatability and reproducibility in accordance with me thods specified by the International Organization for Standardization. Results: Intralaboratory repeatability was less than 0.5% of the diop tric power, and interlaboratory reproducibility, when following a norm alized procedure for correction and conversion, was less than 1.0% of the dioptric power. Conclusion: Tolerance limits of +/-0.30 D in the r ange 0 to 15.00 D, +/-0.40 D for 15.50 to 25.00 D, and +/-0.50 D for 2 5.50 to 30.00 D have been proposed as an international standard for IO Ls. The contribution of IOL power error within the limits of the stand ard are estimated to contribute less than 1.0% to the total error in p ostoperative refractive prediction.