Postoperative Vault Changes After Implantable Collamer Lens Implantation According To Different Sizing Strategies

To evaluate postoperative vault distribution after implantable collamer lens (ICL) implantation using different sizing formulas and combination strategies and to assess agreement between predicted and measured vault over time.

Aier Eye Hospital, Guangzhou, Affiliated to Jinan University

This retrospective study included 205 patients (364 eyes) who underwent EVO V4c Visian ICL implantation for myopia. Based on sizing recommendations from the OCOS system, NK formula, and KS formula, eyes were classified into four groups: three-formula consensus, two-formula consensus, single-formula selection, and non-consensus selection. Vault distribution at 12 months was compared among groups. Agreement between predicted vault (NK and KS) and measured vault at 3, 6, and 12 months was analyzed to determine systematic bias and temporal trends.

No significant intergroup differences existed in ideal or low vault proportions. High vault proportion differed significantly (P=0.006), driven by the OCOS subgroup within the single-formula selection group. Multi-formula consensus yielded narrower vault dispersion than single-formula selection. The NK formula demonstrated persistent positive bias at all time points (P<0.001), increasing over time. The KS formula showed smaller overall bias, with closest agreement at 6 months (P=0.762). Both formulas' predictive bias increased with larger ICL sizes, peaking in the 13.2 mm group. Although larger lenses exhibited greater vault reduction, temporal patterns paralleled across sizes: early decline followed by stabilization after 6 months.

Multi-formula consensus was associated with a more concentrated postoperative vault distribution and reduced high-vault risk. The KS formula demonstrated superior predictive performance; however, size-dependent bias persisted, particularly in larger ICL sizes.