Comparison of the effect of capsular bend on the rotational stability between two toric intraocular lenses

Purpose: To compare the effect of capsular bend on the rotational stability between two toric intraocular lenses (IOLs). Setting: Eye Hospital of Wenzhou Medical University, Hangzhou, Zhejiang Province, China Design: A prospective study Methods: Patients with pre-existing astigmatism received AcrySof IQ(SN6AT) or TECNIS(ZCT/ZMT) toric IOL during cataract surgery. CASIA2 was used to record the toric IOL axial orientation and capsular bend index(CBI) at 1-day, 1-week, 1-month and 3-month intervals postoperatively. The postoperative rotational stability and CBI of both models were compared. Results: Fifty-eight eyes from fifty-eight patients were enrolled in the study. The total misalignment of the TECNIS(ZCT/ZMT) group(6.96±5.10°, 7.41±5.19°, 6.93±5.29°, and 6.86±5. 27°) was significantly higher than that of the Acrysof IQ(SN6AT) group (3.55±2.21°, 4.00±2.74°, 3.72±2.72° and 3.52±2.50°) at all follow-up intervals (P < 0.05). The mean rotation of the TECNIS(ZCT/ZMT) group(2.66±2.18°) was significantly greater than that of the Acrysof IQ(SN6AT) group(1.65±1.47°) from 1-day to 1-week after surgery(P < 0.05). The capsular bend formation in the TECNIS(ZCT/ZMT) group was delayed compared to the Acrysof IQ(SN6AT) group (P< 0.05, at 1-week, 1-month, and 3-month intervals). The TECNIS(ZCT/ZMT) group showed fibrosis in the peripheral anterior capsule, leading to its stretching away from the IOL surface, while the AcrySof IQ(SN6AT) group exhibited gentle adherence of the anterior capsule to the IOL surface. Conclusions: The AcrySof IQ toric IOL(SN6AT) exhibited greater rotational stability than the TECNIS toric IOL(ZCT/ZMT), which may partially result from the delay in capsular bend formation of TECNIS at 1-day to 1-week follow up after surgery.