Abstract
BackgroundThe use of capsular tension ring (CTR) implantation to treat cataract patients with weak zonules is still controversial. The aim of this study was to examine the effects of CTR implantation on capsular stability after phacoemulsification in patients with weak zonules, especially patients who have undergone pars plana vitrectomy (PPV) or those who suffer from severe myopia.MethodsA total of 42 patients who underwent phacoemulsification and received an intraocular lens (IOL) were randomized to undergo CTR implantation or not. The control and CTR groups were compared in terms of uncorrected distant visual acuity (UDVA), best corrected distant visual acuity (BCDVA), refractive prediction error, the area of anterior capsulorhexis, and IOL inclination angle. Follow-up visits were conducted postoperatively at 1 day, 1 week, 1 month and 3 months. Subgroup analyses were performed based on PPV and severe myopia.ResultsSurgery significantly improved UDVA and BCDVA to similar extents in CTR and control patients, and refraction prediction error was similar between the two groups at all follow-up times. At 3 months after surgery, the area of anterior capsulorhexis was significantly larger in CTR patients than in controls (p = 0.0199). These differences were also significant between the subgroups of patients with severe myopia. Vertical IOL inclination was less within CTR groups at 3 months after surgery, especially in patients with severe myopia (p = 0.0286). At 1 week postoperatively, the proportion of individuals whose posterior lens capsule that had completely adhered to the posterior IOL surface was significantly higher among CTR patients (p = 0.023). No serious surgical complications were observed.ConclusionCTR implantation can benefit cataract patients with weak zonules by maintaining the shape of the capsular bag, reducing capsule shrinkage and stabilizing IOL inclination.Trial registrationChinese Clinical Trial Registry ChiCTR-INR-17011217, date of registration April 22, 2017, prospectively registered.
Highlights
The use of capsular tension ring (CTR) implantation to treat cataract patients with weak zonules is still controversial
In Chinese patients, vitrectomy and strong myopia are the frequent causes of a weak zonule, so the present study focused on patients who had undergone pars plana vitrectomy (PPV) or who had severe myopia
Patient enrollment Consecutive cataract patients who were referred to the Department of Ophthalmology at West China Hospital of Sichuan University between December 2017 and December 2018 were eligible for enrollment if (1) phacoemulsification was proposed as a treatment; (2) patients had an axial length > 28 mm, or more than 3 months had passed since PPV; (3) patients had weak zonules based on an average zonular length > 0.7 mm, as measured by ultrasound biomicroscopy; and (4) patients were eligible for phacoemulsification alone or with CTR implants
Summary
The use of capsular tension ring (CTR) implantation to treat cataract patients with weak zonules is still controversial. The aim of this study was to examine the effects of CTR implantation on capsular stability after phacoemulsification in patients with weak zonules, especially patients who have undergone pars plana vitrectomy (PPV) or those who suffer from severe myopia. Zonular weakness makes the lens unstable, which can complicate intraocular procedures such as cataract surgery and increase risk of intraocular lens (IOL) dislocation [1]. People with strong myopia have longer zonular fibers because the axial length is longer, and the wall of the eyeball is thinner. These patients are at increased risk of a loosened capsular bag, unstable anterior chamber, and lens dislocation during cataract surgery. Capsular shrinkage increases tension on zonular fibers, further lengthening and weakening them [1, 4, 6]
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