The Role of Capsular Tension Rings in Intraocular Lens Stability in High Myopia Cataract Patients: A Prospective Self-Controlled Study

Study Purpose:

This study aims to evaluate the effect of capsular tension rings (CTR) on intraocular lens (IOL) stability in cataract patients with high myopia. Each patient will undergo cataract surgery in both eyes, with one eye receiving a CTR and the other eye not receiving a CTR, using the same IOL model in both eyes. Postoperative visual quality and IOL stability will be compared between the two eyes. The study will analyze changes in postoperative visual acuity, refraction, ocular parameters, anterior segment morphology, and IOL positioning to assess the effect of CTR implantation on visual outcomes in highly myopic patients.

Study Methods:

This is a prospective, self-controlled clinical study involving cataract patients with high myopia (axial length ≥ 26.0 mm) scheduled for bilateral cataract surgery. Patients will undergo femtosecond-assisted phacoemulsification and IOL implantation in both eyes, with one eye randomly assigned to receive a CTR and the other not. All procedures will be performed by the same surgeon to ensure consistency. Postoperative follow-up visits will be scheduled at 1 day, 1 week, 1 month, 3 months, and 6 months. Evaluation indicators include uncorrected and best corrected visual acuity (UCVA, BCVA), refractive status, intraocular pressure, anterior segment morphology (anterior segment OCT), IOL decentration and tilt (using anterior segment images), and visual quality (iTrace).

Sample Size and Study Population:

The estimated sample size is 60 patients (i.e., 120 eyes). Each patient will receive CTR implantation in one eye and serve as their own control in the fellow eye. Inclusion criteria: age ≥ 18 years, bilateral cataracts with high myopia eligible for surgery. Exclusion criteria: ocular comorbidities (e.g., glaucoma, retinal disease), history of major ocular trauma or surgery, and other causes of vision loss. Patients will be grouped based on axial length: Group A (AL ≤ 28 mm), Group B (28 mm < AL ≤ 30 mm), and Group C (AL > 30 mm).

Study Procedure:

Participants will be recruited after signing informed consent and passing pre-screening assessments. All subjects will receive detailed explanations regarding study purpose, procedures, risks, and postoperative care. Baseline examinations will include biometry, axial length, anterior segment measurements, and corneal topography. After surgery, patients will be followed up at 1 day, 1 week, 1 month, 3 months, and 6 months. Examinations include visual acuity, refraction, intraocular pressure, IOL position (decentration and tilt via anterior segment OCT), and visual quality analysis (iTrace). All data will be securely managed, and the final analysis will compare visual outcomes and IOL stability between the CTR and non-CTR eyes in highly myopic patients.

Inclusion criteria

• Age ≥ 18 years.
• Diagnosed with bilateral age-related cataracts and scheduled for phacoemulsification with IOL implantation in both eyes.
• High myopia in both eyes, defined as axial length (AL) ≥ 26.0 mm.
• No significant difference in axial length between the two eyes (e.g., interocular AL difference < 1.0 mm).
• Willingness and ability to undergo bilateral surgery within a short interval (e.g., within 1-2 weeks).
• Able to provide informed consent and comply with the study protocol and follow-up visits.

Exclusion criteria

• History of ocular trauma, surgery, or intraocular inflammation in either eye.
• Presence of other ocular diseases that may affect visual outcomes, such as glaucoma, diabetic retinopathy, macular degeneration, or corneal opacity.
• Evidence of zonular weakness, pseudoexfoliation, or significant phacodonesis preoperatively.
• Severe dry eye or poor fixation that may interfere with postoperative imaging.
• Systemic diseases affecting visual function (e.g., uncontrolled diabetes, neurologic disorders).
• Participation in other clinical trials that may affect the study outcomes.