This large retrospective analysis compared the rotational stability of the Acrysoft and Tecnis toric IOLs.
Study design
During the 18-month study, 626 eyes received the Acrysof IOL (Alcon) and 647 received the Tecnis (Johnson & Johnson). All surgeries were performed by the 2 study authors using standardized steps to minimize IOL rotation. Patients were excluded if a digital marking system (Callisto; Carl Zeiss Meditec) could not be used intraoperatively.
First postoperative visits were between 1 and 24 hours after surgery. Surgeons offered repositioning surgery to patients with a misaligned implant, a refractive cylinder of 0.75 D or greater, and an uncorrected visual acuity of 20/30 or worse. Those with misalignment of 10 degrees or greater were usually offered repositioning, even with less refractive cylinder.
Outcomes
The mean rotation for the Acrysof and Tecnis IOLs was 2.72 and 3.79 degrees, respectively (P<0.05). The Acrysof was less likely to rotate postoperatively; 92% of Acrysof IOL eyes rotated 5 degrees or less compared with 82% of eyes with the Tecnis IOL (P<0.0001). Rotation of 10 degrees or less for Acrysof and Tecnis were 98% and 93%, respectively. There were no significant differences in the rates of IOLs that rotated beyond 15 degrees.
Tecnis IOLs displayed a strong predisposition to rotate counterclockwise compared with Acrysof IOLs. Increased axial eye length corresponded to increased risk of rotation in both groups.
The postoperative refractive cylinder, the number of eyes with manifest cylinder of 0.5 D or less, the percentage of eyes with no manifest cylinder, the absolute spherical equivalent error, and BCVA were similar between groups.
Limitations
Despite the significant differences in toric IOL rotation between the groups, there was no difference in refractive outcomes. The rates of IOL rotation in this study refer only to the first postoperative visit, therefore potentially missing late rotational differences that may occur after this period. Though more eyes in the Tecnis group required repositioning (3.1% vs. 1.6%), this did not reach statistical significance (P=0.10). The authors report that some of the Acrysof eyes requiring repositioning only exhibited significant rotation after the initial postop visit; this rotation would not be captured in the statistical comparisons above. This delayed rotation in certain Acrysof eyes deserves further investigation. The researchers kept eyes “soft” at the end of surgery to avoid distention of the capsular bag and minimize risk of toric IOL rotation. However, they estimated the pressure to be in the single digits using palpation, a known risk factor for wound leakage that could affect the overall toric IOL stability.
Clinical significance
The Acrysof toric IOL showed significantly greater rotational stability than the Tecnis toric IOL. Overall, rates of toric IOL rotation were quite low, and both IOLs resulted in excellent refractive outcomes. Continued advances in IOL material and design may further reduce the risk of rotation.