Improvement in the ideal range of vault after implantable collamer lens implantation: a new vault prediction formula

Abstract

BackgroundTo derive and validate a novel vault prediction formula to improve the predictability and safety of implantable collamer lens (ICL) implantation.MethodsThirty-five patients (61 eyes) with previous posterior chamber intraocular lens implantation were included. Various parameters, such as horizontal-visible iris diameter (HVID), photopic pupil diameter (PPD), axial length (AL), white-to-white (WTW), anterior chamber width (ACW), angle-to-angle (ATA), crystalline lens rise (CLR), anterior chamber depth (ACD), horizontal sulcus-to-sulcus (HSTS), and ciliary sulcus angle (CSA) were measured. Vault was measured at 3 months after surgery using CASIA2 anterior segment optical coherence tomography. The formula was derived using multiple linear regression analysis and named as WH formula. It was validated in 65 patients (118 eyes) to determine the percentage of the ideal postoperative vault range and to compare the differences between the WH formula and the NK, KS, and STAAR formulas.ResultsFinal ICL size, ATA, CSA, and CLR were included in the prediction formula model (adjusted R2 = 0.67, p < 0.001). The achieved vault 1 month after the surgery was 556.19 μm ± 166.98 μm in the validation group, and the ideal vault range was 200–800 μm (92%). The difference between the achieved vault and that predicted using the WH formula was not statistically significant (p = 0.165), whereas the difference between the achieved vault and that predicted using the NK and KS formulas was statistically significant (p < 0.001 and p < 0.001, respectively). The 95% agreement limit range of the achieved vault and the vault predicted using the WH formula was narrower than those predicted using the NK and KS formulas (−295.20–258.82 μm).ConclusionThis study combined the results of optical coherence tomography and ultrasound biomicroscopy measurements of the anterior segment of the eye and incorporated ciliary sulcus morphology quantification into the prediction formula. The study derived a prediction formula for vault by combining ICL size, ATA, and CLR. The derived formula was found to be superior to the currently available formulas.

Implantable Collamer Lens Procedure Planning: A Review of Global Approaches

“…Wu et al recently reported on a new formula (the WH formula) that combines conventional biometric information with OCT and UBM parameters. 27 When ICL size, ATA, CLR, and CSA were all used to predict the vault with this formula, 92% of eyes achieved a postoperative vault in the targeted range. The authors suggest that ciliary sulcus angle (CSA), which they measured manually using ImageJ software and Suoer SW-3200 UBM images, represents a good quantitative assessment of the ciliary sulcus morphology, which they posit affects postoperative vault in ways that are difficult to predict.…”

“…The authors suggest that ciliary sulcus angle (CSA), which they measured manually using ImageJ software and Suoer SW-3200 UBM images, represents a good quantitative assessment of the ciliary sulcus morphology, which they posit affects postoperative vault in ways that are difficult to predict. 27 They do not use ACD in the prediction formula, believing that ACD does not directly affect the postoperative vault, but rather, influences the individual’s tolerable vault range. A deeper anterior chamber, therefore, can accommodate a larger vault but does not cause one, and a shallow chamber, by this logic, would have a tighter ideal range for the vault.…”

“…A deeper anterior chamber, therefore, can accommodate a larger vault but does not cause one, and a shallow chamber, by this logic, would have a tighter ideal range for the vault. 27 …”

“… 23 , 25 This may be due in part to problems with inter-examiner variability and poor reproducibility increasing the error of STS measurements. 15 , 22 , 26 , 27 Additionally, UBM can be time consuming in the clinic and uncomfortable for patients. 26 , 28 …”

“… 30 The positioning of the ICL haptic outside the ciliary sulcus and features of ciliary sulcus morphology that affect the resting position of the ICL are strongly suspected to influence vault. 27 , 30 , 31 …”