The following is a summary of “Comparison of a new implantable collamer lens formula to standards formulas using spectral domain optical coherence tomography,” published in the September 2023 issue of Ophthalmology by Eldanasoury et al.

Researchers performed a retrospective study to develop a new implantable collamer lens (ICL) sizing formula using spectral-domain optical coherence tomography (SD-OCT) data and compare vault outcomes with Online Calculation and Ordering System ^TM (OCOS) and NK2 formula.

They evaluated consecutive eyes (n = 237) undergoing ICL/toric ICL implantation. ICL vaults were measured, and performed a what-if analysis to predict vault values using the NK2 formula with SD-OCT data. A new formula (EPB) was created using multiple regression analysis with different parameters than the NK2 formula. The predicted vaults from both formulas were compared to the actual vaults.

The results indicated that parameters correlated with optimal ICL size included white-to-white, anterior chamber width, lens rise, and desired refractive correction. The mean postoperative vault measured 489 ± 258 μm. In the last visit, 94.5% of eyes fell within the manufacturer’s acceptable vault range. Predicted vaults within this range were 74% with the NK2 formula and 87% with the EPB formula. In contrast, 6% had a predicted vault less than 100 μm with the EPB formula compared to 1% in actual outcomes. The NK2 formula predicted higher vaults, while the EPB formula closely matched real postoperative vaults but had slightly more cases with extreme vault heights.

They concluded that SD-OCT data with OCOS result in good postoperative vaults, while NK2 and EPB formulas need further refinement.

Source: link.springer.com/article/10.1007/s10792-023-02861-5