Impact of crystalline lens thickness on early post-operative implantable collamer lens vault - A pilot study

Purpose: The purpose of this study was to assess the association between crystalline lens thickness (CLT) and early postoperative implantable collamer lens (ICL) vault and to evaluate vault stability during the first postoperative week in eyes with persistently low vault requiring upsizing. Methods: Six eyes with ICL vault <100 µm on postoperative day 1 (POD1) and persistent low vault at day 7 (POD7), leading to explantation and implantation of a one-size larger ICL, were included in the study. Preoperative CLT was measured by IOLMaster 700; postoperative vault at POD1 and POD7 was measured by anterior segment optical coherence tomography. Descriptive statistics (mean ± standard deviation, range) were computed for CLT, vault at POD1, vault at POD7, and vault change (POD7 − POD1). Pearson and Spearman correlations between CLT and vault at each time point, and between CLT and vault change, were calculated ( P < 0.05). Results: Mean CLT was 4.91 ± 0.12 mm (range 4.77–5.10). Mean vault was 18.7 ± 14.8 µm (0–34) at POD1 and 15.7 ± 12.9 µm (0–32) at POD7; mean change was −3.0 ± 2.8 µm. Pearson correlation between CLT and vault showed a negative correlation (POD1 r = −0.51 ( P = 0.30); POD7 r = −0.53 ( P = 0.28)). Spearman’s rho showed similar moderate negative trends (POD1 ρ = −0.75, P = 0.08; POD7 ρ = −0.65, P = 0.16). Correlation between CLT and vault change was weak (Pearson r = 0.27, P = 0.61; Spearman ρ =0.32, P = 0.53). Vault remained persistently low with minimal change. Conclusions: In this small series, thicker lenses appeared moderately associated with lower early vaults, though not significantly. Vault persisted at low levels with minimal early change. Preoperative CLT should be integrated with other biometric parameters to minimize low-vault risk and the need for secondary ICL exchange. Larger prospective studies are warranted for further refinement of ICL sizing protocols.