Improving the preoperative prediction of the anterior pseudophakic distance for intraocular lens power calculation

PURPOSE: To establish a new formula for intraocular (IOL) power calculation. SETTING: Private practice, Lynwood, California, USA. DESIGN: Retrospective observational and prospective evaluation. METHODS: In this 2-part retrospective observational study followed by a prospective evaluation, the postoperative anterior pseudophakic distance (APD) was correlated with the ante-nucleus distance (AND), the nucleus thickness (NT) of the cataractous lens, and the axial length. An estimated APD (EAPD) equation was established and used prospectively in a new formula on eyes scheduled for cataract surgery. RESULTS: Correlations were made in 90 operated eyes, and the EAPD equation was used in a new formula on 110 eyes scheduled for cataract surgery. Using the new IOL power formula, the median absolute error was 0.28 D with 82.7% of the eyes within ±0.50 D and 100% within ±1.00 D. CONCLUSIONS: The new IOL power formula with its incorporated EAPD equation performed well. FINANCIAL DISCLOSURE: H.J.S. has a pending patent on this system and method for determining IOL lens power.