Validation of the vault prediction model based on the sulcus-to-sulcus diameter and lens thickness: a 925-eye prospective study

Abstract

Background To verify the accuracy and stability of the prediction formula based on the ciliary sulcus diameter and lens thickness and to analyse factors influencing the prediction results. Methods In total, 925 eyes from 506 subjects were enrolled in this prospective study between July 1, 2020, and June 30, 2021. Subjects were divided into four seasons, each spanning three months. The target vault was set to be between 300 μm and 700 μm according the prediction formula. The actual vault was measured one month postoperatively. The Bland–Altman test, 95% confidence intervals (95% CI) and 95% limits of agreement (95% LoA) were used to evaluate the agreement between the predicted vault and the actual vault. Eyes with absolute prediction errors greater than 300 μm were further analysed. Results The mean predicted vaults for the four seasons were 503 ± 99, 494 ± 96, 481 ± 92 and 502 ± 93 μm, while the mean actual vaults were 531 ± 189, 491 ± 179, 464 ± 179 and 529 ± 162 μm, respectively. The predicted and actual vaults of the overall subjects were 493 ± 95 and 500 ± 180 μm, respectively. Of the 925 eyes, 861 eyes (93.08%), 42 eyes (4.54%), and 22 eyes (2.38%) showed a normal vault, high vault, and low vault, respectively. Bland–Altman plots showed that the mean difference between the actual vault and predicted vault overall (± 95% LoA) was 6.43 ± 176.2 μm (-339 to 352 μm). Three UBM features may lead to large prediction errors (more than 300 μm): wide iris-ciliary angle (ICA), iris concavity and anteriorly positioned ciliary body. Conclusions This study demonstrated the accuracy and stability of the prediction formula through the validation of a large sample size and a long time span. Wide ICA, iris concavity and anteriorly positioned ciliary body may have an effect on vault.

The influence of iris -ciliary angle (ICA) on the vault after implantation of V4c implantable collamer lens: a chain mediation model of ICL haptic related factors

“…This finding is consistent with our previous study [ 11 ] which revealed that ICA was the major risk factor for excessive vault (> 1000 μm), with every 1-degree reduction in ICA, the risk of excessive vault increased by 4%. Zhu et al [ 17 ] developed a regression equation to predict the vault when testing the accuracy of the formula they found that wide ICA, iris concavity and anteriorly positioned ciliary body may be the reasons for large prediction errors. To our knowledge, the mechanism of the relationship between the ICA and the vault has not been well elucidated, and we hypothesize that ICL haptic-related parameters may play an important role in this relationship.…”

Comparison of the Accuracy of Seven Vault Prediction Formulae for Implantable Collamer Lens Implantation

“… The Zhu formula, based on ICL size, HSTS, VSTS, and LT, was used to predict the vault. Vault (μm) = -1369.05 + 657.121 × ICL size (mm)—287.408 × HSTS (mm)—432.497 × LT (mm)—137.33 × VSTS (mm) [ 11 ]. The predicted vault was obtained by inputting the actual implanted ICL size, HSTS, VSTS, and LT into Excel.…”