Ultrasound Biomicroscopy Analysis of Ciliary Cleft, Ciliary Body, and Ciliary Muscle Changes Following Capsular Tension Ring Implantation in Dogs

Objective To evaluate the influence of capsular tension ring (CTR) implantation during phacoemulsification on ciliary cleft, ciliary body, and ciliary muscle morphology in dogs. Methods This prospective observational cohort study included 23 eyes from 16 dogs that underwent phacoemulsification with IOL implantation alone (11 eyes/9 dogs) or combined with CTR implantation (12 eyes/11 dogs). Four dogs contributed one eye to each group. Ultrasound biomicroscopy (UBM) was performed preoperatively and at 2–4 weeks and more than 3 months postoperatively to evaluate the iridocorneal angle, ciliary cleft, ciliary body, and ciliary muscle. Results No preoperative differences were identified between groups. Compared with the IOL group, CTR implantation was associated with a smaller ciliary cleft, anterior displacement and compression of the ciliary body toward the corneoscleral region and thinning of the deeper ciliary muscle layers during the postoperative period. These morphological differences remained consistent at the long‐term follow‐up. Ciliary body compression by the CTR was observed in 5 of 12 eyes. Intraocular pressure (IOP) did not differ between groups. Conclusions CTR implantation was associated with measurable morphological changes in the ciliary cleft, ciliary body, and ciliary muscle without affecting IOP. Although these changes were statistically significant, they were not associated with detectable adverse clinical effects during the follow‐up period.