Toric IOL positioning with a no-touch head-up display axis alignment

To compare a new no-touch alignment technique for toric intraocular lenses (IOL) with the conventional technique that uses a manual pendulum.

In this retrospective case-control study, patients who underwent toric IOL implantation using two different alignment techniques (digital Callisto^® system vs. manual-pendulum-based marking) were compared in a vector analysis using the Alpins method and an analysis of variance regarding corrected and uncorrected visual acuity and the deviation of the achieved IOL axis from the targeted axis.

Sixty-one eyes were included into analysis. Thirty-six of these surgeries were performed via the Callisto^® system and 25 eyes via pendulum-based corneal markings. Median IOL axis misalignment was 3° in both groups. Median uncorrected distance visual acuity was 0.097 logMAR versus 0.200. Median best-corrected visual acuity was 0.000 logMAR versus 0.097. All these data were below the range of statistical significance (p > 0.05). Vector analysis showed no significant difference for TIA [median of 3.14 diopters (D) vs. 2.73 D], SIA (median of 3.82 D vs. 3.79 D), DV (1.18 D vs. 1.08 D), and CI (1.23 vs. 1.29). Median angle of error was 1.96° versus - 0.44° (p > 0.05).

We found no significant difference in the refractive results, the IOL positioning, and the best-corrected and uncorrected distance visual acuity between the two compared methods. Nevertheless, the Callisto^® IOL alignment system delivers a standardized and easy-to-use technology. In particular, less-experienced surgeons might benefit from this marking technique.