Implantation of Capsular Tension Ring in Primary Angle Closure Patients With Zonular Laxity or Dialysis

Primary angle closure glaucoma (PACG) is the main type of glaucoma in China, which includes acute and chronic PACG. According to the International Society of Geographical and Epidemiological Ophthalmology (ISGEO), this spectrum of disease is divided into acute angle closure crisis (AACC), primary angle closure suspect (PACS), primary angle closure (PAC) and PACG. Previous researchers have reported that with the wider use of lens extraction and intraocular lens (IOL) implantation combined with anti-glaucoma surgery in the treatment of PAC and PACG, the prevalence of zonular laxity or dialysis in primary angle closure disease (PACD) was found to be relatively high. In one of the studies performed by the investigators, the proportion of zonular laxity or dialysis was 46.2%, significantly higher than that in the age-related cataract patients (control group), which was 6.0%. In PACD patients with zonular laxity or dialysis, whether or not should the investigators implant capsular tension ring (CTR), the efficacy and safety of CTR implantation, and if there is any difference in the prevalence of complications during and after surgery between patients with and without CTR implantation remain unclear. The purpose of this study was to investigate the efficacy and safety of CTR implantation in PACD patients with zonular laxity and zonular dialysis ≤ 4 clocks.

Patients with PACD who are scheduled to have phacoemulsification and IOL implantation combined with goniosynechialysis are recruited. All recruited patients attended comprehensive eye examinations and interviews. Past history of ocular and systemic diseases, family and personal history, history of ocular trauma and surgery were interviewed. And the patients underwent ophthalmic examinations including visual acuity tests (presenting visual acuity \[PVA\] and best-corrected visual acuity \[BCVA\]), subjective refraction, intraocular pressure (IOP) measurements, slit-lamp examination, fundus photography, gonioscopy, ocular biometry using IOL Master 700, ultrasound biomicroscopy, anterior segment optical coherence tomography (ASOCT) imaging. All patients provide informed consent for inclusion in the study.

All surgery procedures were performed by the same surgeons (CYQ) using the same standard operation procedure. All patients use the same type of foldable IOL calculated using SRK/T formula. During the surgery, patients with wrinkling of the anterior capsule (multiple sinusoidal folds were formed) during continuous curvilineal capsulorhexis (CCC) at the needle or forceps tip but without infolding of peripheral capsule or visualisation of the capsular equator during the cortical or nuclear removal, or, wrinkling of the anterior capsule during CCC with infolding of peripheral capsule and visualisation of the capsular equator ≤ 4 clocks of range during the cortical or nuclear removal, were finally included in the study and randomly assigned (using a random-number table generated by SAS) with equal probability to either CTR group (with CTR implantation during the surgery) and control group (without CTR implantation during the surgery). All patients included in the CTR group use the same type of CTR. The investigators recorded the complications during the surgery including vitreous prolapse, hyphema, vitreous hemorrhage, damage of iris and lens capsule, et al.

Postoperatively, all patients received similar routine medication comprising topical prednisolone acetate (six times a day for 1 week and tapered down by 1 time every week), topical levofloxacin hydrochloride (four times a day for 1 month), and Tobramycin and Dexamethasone Eye Ointment (1 time every night for 1 month).

Postoperative examinations were performed at 1 day, 1 week, 1 months, 3 months, 6 months and 12 months. During the follow-up visits, a complete ophthalmic examination was performed including PVA, BCVA, subjective refraction, non-contact IOP measurement, slit-lamp examination, slit-lamp photography after pupil dilation, ASOCT, gonioscopy, and fundus imaging.

Eligibility Criteria:
Inclusion Criteria:

* Age: 45-79 years old
* Continuous cases diagnosed with AACC, PACS, PAC and PACG in glaucoma department of Beijing Tongren Hospital from October 1st, 2022 to December 31th, 2024 and undergo phacoemulsification lens extraction and intraocular lens implantation combined with goniosynechialysis
* Wrinkling of the anterior capsule during manual continuous circular capsulorhexis (CCC) but without infolding of peripheral capsule or visualization of the capsular equator, or, wrinkling of the anterior capsule during manual capsulorhexis and combined with visualization of capsular equator and infolding of peripheral capsule ≤ 4 clocks (lens subluxation)
* The eye of each subject that meet the inclusion criteria is included and if both eyes meet the inclusion criteria, the first eye that undergo the surgery is included

Exclusion Criteria:

* Past history of intraocular surgeries including trabeculectomy, peripheral iridotomy, glaucoma valve implantation, vitrectomy, and so on
* Past history of laser peripheral iridotomy or iridoplasty
* Past history of ocular trauma or signs referring to ocular trauma
* Ocular diseases that may cause zonulopathy, including choroidal detachment, retinal detachment, ciliary body detachment, intraocular tumor and so on
* Lens related secondary glaucoma, including spherophakia, Marfan syndrome, homocystinuria and son on
* Other secondary angle closure glaucoma, including neovascular glaucoma, iritis related secondary glaucoma and so on
* Visualization of capsular equator and infolding of peripheral capsule \> 4 clocks during the surgery
* Anterior or posterior capsule rupture during the surgery which makes it impossible for CTR implantation