This is a self-controlled randomized clinical trial to investigate the effect of capsular tension ring (CTR) implantation on intraocular lens (IOL) position in cataract patients with retinitis pigmentosa(RP). Each patient will receive CTR implantation in one eye, with the fellow eye serving as control. Postoperative outcomes, including visual acuity, IOL position, and postoperative complications will be compared between eyes.

Patients with retinitis pigmentosa (RP) have a higher risk of developing cataracts, often accompanied by abnormalities such as zonular laxity and vitreous liquefaction, which increases the risk of intraocular lens (IOL) tilt, decentration, and capsular contraction after surgery. The capsular tension ring (CTR) can support the zonules and maintain the stability of the capsular bag, but its effect in RP patients remains controversial.

In this self-controlled clinical trial, we are going to recruit 88 RP patients scheduled for bilateral cataract surgery. Both eyes receive a monofocal DCB00 IOL, while only on eye receives an additional CTR. Follow up visits take place 1 week, 1 month, 3 months, 6 months, and 1 year postoperatively. At the follow up visits, IOL decentration and tilt (determined by anterior segment SS-OCT Casia 2), visual acuity, and postoperative complications will be compared intraindividually at different timepoints.

Inclusion Criteria:

• Age ≥ 18 years.
• Clinical diagnosis of retinitis pigmentosa (RP).
• Bilateral cataract meeting the indications for IOL implantation.
• Willingness to participate in the study and provision of signed informed consent.

Exclusion Criteria:

• History of intraocular surgery.
• Severe zonular weakness (e.g., zonular dialysis >90°, lens subluxation/dislocation)
• Other ocular comorbidity: such as pseudoexfoliation syndrome, ocular trauma, corneal dystrophies, uveitis, etc.
• Severe systemic diseases: such as severe hypertension, diabetes, heart disease, Alzheimer's, Parkinson, etc.