Correlation of iris-ciliary angle with haptic position and vault after implantation of implantable collamer lens.

Purpose: This study aimed to investigate the impact of the iris-ciliary angle (ICA) on the position of the implantable collamer lens (ICL) haptic and vault following ICL implantation.

Methods: A prospective, observational study was conducted using data from 135 patients who underwent horizontal ICL implantation. Patients were categorized into three groups by ICA: ICA1 (0-32°), ICA2 (32-64°), and ICA3 (64-96°) to compare parameters. The parameters correlated with the distance from the iris root to the end of the ICL haptic (IRH) and vault was analysed respectively. A multiple linear stepwise regression model was constructed to estimate IRH.

Results: The vault decreased sequentially across the three groups (P < 0.001) and was negatively correlated with ICA (P < 0.001). The proportion of ICL haptic insertion under the ciliary body was significantly higher in the ICA3 group compared with the ICA1 and ICA2 groups (P = 0.039). Stepwise regression analysis showed that IRH = -1.174 + 0.005 × ICA + 0.118 × horizontal sulcus-to-sulcus (STS) distance (adjusted R² = 0.334, Durbin-Watson value = 1.908, P < 0.001), with ICA as the primary influencing factor (β = 0.536, P < 0.001), followed by horizontal STS distance (β = 0.348, P < 0.001).

Conclusions: When the ICA is excessively large, the ICL haptic is more likely to be inserted under the ciliary body. An increase in ICA is associated with a greater IRH and a lower vault.

Key messages: What is known: • More posterior chamber anatomical parameters of eyes are needed to improve the accuracy of predicting the vault. • A negative correlation exists between the iris-ciliary angle (ICA) and vault.

What is new: • When the ICA is excessively large, the ICL haptic is more likely to be inserted under the ciliary body. • The ICA is the primary influencing factor when predicting the distance from the iris root to the end of the ICL haptic (IRH).