PURPOSE: To develop and test a formula for contact lens calculation in aphakic infants. This formula, termed the "aphakic Contact Lens" (aCL) formula, utilizes preoperative axial length and keratometry data. METHODS: This retrospective, consecutive, two-center study used data derived from a development cohort (Freiburg, Germany) to create and optimize the aCL formula in aphakic eyes. A separate validation cohort (Frankfurt, Germany) was used to validate its predictive performance. The accuracy of the aCL formula was compared against: retinoscopy, a previously reported formula (Trivedi and Wilson, TW), and the use of a + 32.0 diopter (D) CL. Performance was evaluated using the prediction error (PE), absolute prediction error (AE) and the number of eyes within a certain range from retinoscopy (± 0.5D, ± 1.0D, ± 2.0D). RESULTS: The aCL formula demonstrated comparable absolute prediction errors to retinoscopy (median AE 0.53D vs. 0.69D) and outperforms the TW formula or + 32D CL (median AE 3.25D and 2.63D). The number of eyes within ± 0.5D (38.3%) is lower compared to retinoscopy (50.0%), but comparable for ± 1.0D and better for ± 2.0D (61.7% vs. 66.7%, 83.3% vs. 72.2%). Both perform better than TW formula and + 32.0D (ranging from 0.0% for ± 0.5D to 33.3% for ± 2.0D). CONCLUSIONS: The aCL formula is a reliable and accurate tool for determining CL power in aphakic infants. It performed superior to other formula-based and default strategies and is comparable to a retinoscopy. Still, follow-up studies with larger cohorts are needed to validate this outcome.
Lwowski et al. (Mon,) studied this question.