Characteristics of biological parameters and implantable collamer lens (ICL) size selection in moderate, high, and super-high myopia eyes.

Objective: To analyze the characteristics of anterior segment biometric parameters in moderate, high, and super-high myopia eyes for ICL size selection.

Methods: A total of 246 eyes of 131 patients were included in this prospective observational cohort study. Preoperative axis length (AL), central keratometry (Kc), central corneal thickness (CCT), white-to-white (WTW), internal anterior chamber depth (ACD), trabecular iris angle (TIA), anterior chamber width (ACW), angle-to-angle distance (ATA), crystalline lens rise (CLR), lens thickness (LT), sulcus-to-sulcus (STS), ICL size, and postoperative vault at 1 month were recorded and compared among the different degrees of myopia groups.

Results: The moderate myopia showed smaller ACD and TIA than high and super-high myopia (P < 0.05). A higher proportion of CLR positive (+) was in the moderate myopia group (65%), while the super-high myopia group had a higher proportion of CLR negative (-) (55.3%). (P = 0.047). There were no statistical differences among the myopia groups in WTW, ATA, ACW, STS, LT, and postoperative vault (P>0.05). In different degrees of myopia groups, vertical ATA, ACW and STS were longer than horizontal ATA, ACW and STS (P < 0.001), and horizontal-STS showed a higher correlation with horizontal-ATA (r = 0.655) and horizontal-ACW (r = 0.660) than with WTW (r = 0.591). The 12.1 mm size ICL was slightly selected in moderate myopia (35.8%) more than high myopia (14.6%) and super-high myopia (26.3%) (P = 0.013).

Conclusion: Compared to high and super-high myopia, moderate myopic eyes exhibited smaller ACD, TIA while similar WTW, ATA, ACW and STS, with the lens positioned more anteriorly. It should be concerned to the effect of sagittal axis parameters ACD and CLR on the ICL size in different degrees of myopia.