This is a randomized controlled trial to investigate the effect of capsular tension ring (CTR) implantation on intraocular lens (IOL) tilt and decentration in cataract patients with high myopia.

Exact positioning and alignment of the IOL with the visual axis are the prerequisites of high-quality visual performance after cataract surgery. A certain degree of IOL tilt and decentration occur after uneventful cataract surgery, most of which are clinically tolerant. However, the relatively large capsular bag volume, zonular weakness, and vitreous liquefaction in cataract patients with high myopia may increase the IOL position instability, such as tilt, decentration and even dislocation, leading to the deterioration of visual function. Thus, how to improve the long-term stability of IOL position in high myopic cataract patients is an urgent issue to be addressed.

Previous studies have shown that CTR implantation during cataract surgery can increase the IOL stability in patients with normal axial length; however, its impact on IOL position of cataract patients with high myopia remains unclear.

In this randomized clinical trial, patients who meet the inclusion criteria will be divided into three layers according to the axial length:

(1)26mm≤AL<28mm (2)28mm≤AL<30mm (3)AL≥30mm

We are going to recruit 186 patients in total, with 62 patients in each layer. Patients on each layer will be randomly divided into experimental group (CTR implantation) and control group (only IOL implantation). If both eyes of a patient meet the inclusion criteria, only the first operated eye is included in the statistics analysis.

All included patients will be followed up at 1 week, 1 month, 3 months, 6 months, and 1 year postoperatively. Visual acuity, IOL tilt, IOL decentration, posterior capsule attachment with IOL, anterior capsule contraction, posterior capsular opacification, and visual quality will be measured and compared between the experimental group and the control group at different timepoints.

Inclusion Criteria:

1. > 18 years old;
2. axis length≥26mm;
3. Visually significant cataract;
4. The patient is willing and able to complete all necessary follow-ups and examinations.

Exclusion Criteria:

1. Intraoperative or postoperative complications: such as intraoperative posterior capsular rupture, zonular dehiscence, secondary glaucoma, endophthalmitis, etc.;
2. Other ocular comorbidity: such as keratopathy, glaucoma, uveitis, retinopathy, lens dislocation and ocular trauma, etc.;
3. History of intraocular surgery;
4. Severe systemic diseases: such as severe hypertension, diabetes, heart disease, Alzheimer's, Parkinson, etc.;
5. Any condition that the study physician considers to be an impediment to the clinical trial.