This is a single-blind, single-center, parallel-group randomized controlled trial with the following objectives: First, researchers aim to compare the clinical efficacy of 2mm and 2.5mm post-limbal needle insertion in sutureless transscleral IOL fixation for patients with congenital ectopia lentis. Second, the goal is to investigate the mean absolute refractive prediction error, IOL tilt and decentration, uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), and corneal endothelial cell count at 3 months postoperatively. Third, it intends to explore the incidence of postoperative complications of the two needle insertion positions in this specific surgical method. Finally, this study aims to provide evidence for ophthalmic clinical practice, explore the optimal needle insertion point, and offer more precise and safe surgical plans for patients requiring sutureless transscleral IOL fixation.

This is a professional translation conforming to medical academic writing standards (with unified key terms and specified abbreviation as required):

For patients with insufficient capsular bag support due to congenital developmental abnormalities, trauma, or other reasons, who have indications for intraocular lens (IOL) implantation, IOL suspension surgery is the main surgical method. Sutureless transscleral IOL fixation is one of the commonly used IOL suspension surgeries currently. Compared with traditional transscleral suture fixation, sutureless transscleral IOL fixation can effectively reduce suture-related complications while ensuring safety and effectiveness, with higher surgical safety.

In transscleral IOL fixation, previous studies have commonly used 2mm and 2.5mm post-limbal positions as needle insertion sites. The 2.5mm post-limbal needle insertion point has a smaller mean absolute refractive prediction error and better clinical efficacy postoperatively. As an IOL suspension surgery, differences in needle insertion positions may affect postoperative refractive status, IOL stability, visual outcomes, and other parameters. Although existing literature has evaluated the overall clinical efficacy and safety of sutureless transscleral IOL fixation, to date, no study has systematically compared the clinical efficacy of this commonly used IOL suspension surgery at different needle insertion positions. Therefore, evaluating the impact of different needle insertion positions on surgical outcomes is crucial for optimizing surgical strategies and improving treatment precision.

In this randomized controlled trial, the investigators will systematically investigate the clinical efficacy of 2mm and 2.5mm post-limbal needle insertion points in sutureless transscleral IOL fixation. Through this study, the investigators aim to provide evidence for ophthalmic clinical practice, explore the optimal needle insertion point, and offer more precise and safe surgical plans for patients requiring sutureless transscleral IOL fixation.

Inclusion Criteria:

1. Patients aged 4-18 years (regardless of gender) who meet the indications for transscleral suture-fixated intraocular lens implantation
2. Patients who can complete a follow-up period of at least 3 months after surgery;
3. Patients or their legal guardians who provide informed consent to participate in this study.

Exclusion Criteria:

1. Patients with concurent secondary qlaucoma, retinal detachment, strabismus, or other relevant ocular complications (excludingrefractive errors);
2. Patients participating in other trials that may affect the results of this study.

This study adopts a single-blind design, with no blinding of investigators but with blinding of participants and assessors implemented. To reduce bias under the single-blind condition, trial-related personnel involved in participant screening remain blinded, and clinical staff conducting routine ophthalmological examinations as well as data analysts are kept blinded to the treatment allocation.