OBJECTIVE The purpose of this study was to compare the tilt and decentration of one-piece anti-vaulting haptic intraocular lenses (IOL) and three-piece C-loop haptic IOLs in paediatric eyes undergoing secondary IOL implantation into the ciliary sulcus. METHODS Paediatric aphakic patients receiving either one-piece anti-vaulting haptic or three-piece C-loop haptic IOL implants into the ciliary sulcus were enrolled in this prospective non-randomized interventional study and followed up for 3 years. IOL decentration and tilt were measured using Scheimpflug images. Preoperative and postoperative information, including demographic data and ocular biometric parameters and complications, were collected and analysed. RESULTS Among 123 eyes of 79 paediatric patients, there were 72 eyes (58.54%) in the anti-vaulting haptic IOL group and 51 eyes (41.46%) in the C-loop haptic group. The anti-vaulting haptic IOL group had a lower incidence of clinically significant vertical IOL decentration than the C-loop haptic IOL group (23.88% vs. 43.14%, p = 0.037). No intergroup differences were observed in vertical or horizontal tilt or in horizontal decentration (all p > 0.05). One-piece anti-vaulting haptic IOL implantation was associated with a lower risk of clinically significant vertical decentration than three-piece C-loop haptic IOL implantation (odds ratio: 0.42, p = 0.037). There was a higher incidence of IOL dislocation in the C-loop haptic IOL group (15.22% vs. 4.17%, p = 0.046). CONCLUSIONS In paediatric aphakic eyes undergoing secondary IOL implantation into the ciliary sulcus, one-piece anti-vaulting haptic IOLs can reduce the risk of clinically significant vertical IOL decentration compared with three-piece C-loop haptic IOLs and may favour long-term IOL positional stability.