The following is a summary of “Comparison of Predictability in Vault Using NK Formula and KS Formula for the Implantable Collamer Lens Surgery,” published in the July 2024 issue of Ophthalmology by Zhong et al.

Researchers conducted a retrospective study comparing the accuracy of the NK and KS formulas in predicting vault after EVO-implantable collamer lens (ICL) implantation.

They involved 106 eyes from 57 patients who underwent ICL-V4c implantation. Preoperative vault predictions were made using the NK and KS formulas, while postoperative measurements were obtained using anterior segment optical coherence tomography (AS-OCT) at 1 month. The study analyzed the agreement between predicted and actual vaults and assessed the correlation between the achieved vault and various biometric parameters.

The result showed that the mean achieved vault was 605.25 ± 212.72 µm, significantly smaller than the vaults predicted by the NK formula (710.08 ± 195.08 µm) and the KS formula (673.80 ± 212.76 µm) (P<0.05). The average difference between the achieved vault and the predictions was −104.82 μm (95% LoA: −600.38 to 391.19 μm) for the NK formula and −68.55 μm (95% LoA: −628.91 to 491.82 μm) for the KS formula. Factors independently associated with the achieved vault included anterior chamber depth (ACD), vertical sulcus-to-sulcus (V-STS) diameter, and crystalline lens rise (CLR) (P<0.05). No significant difference was observed in absolute prediction error (APE) between the 2 formulas.

Investigators concluded that the NK formula provided better consistency and lower error than the KS formula for the 12.6 mm ICL, while AS-OCT overestimated vaults for the 13.2 mm ICL, indicating that relying on the formulas alone for vault prediction is not recommended.

Source: onlinelibrary.wiley.com/doi/full/10.1155/2024/4256371