The main objective of our study was to evaluate the contribution of automated conjunctival registration in the alignment of toric intraocular lenses by comparing automated registration optimized with Callisto^® to manual marking of the horizontal axis.

We performed a prospective, descriptive, monocentric study on patients undergoing cataract surgery with a toric intraocular lens (Asphina 709 Zeiss), performed by a surgeon with good experience in toric implants, between September 2016 and March 2017. We analyzed the agreement between the manual marking of the 0–180° axis versus the one automatically generated by the Callisto™, as well as the alignment of the IOL and the refractive results at 1 month.

We included 50 eyes of 38 patients. The mean corrected astigmatism was 1,9 D. The mean difference between the 2 axes was 4,7° [0–12.3°]. Only 50 % of the preoperative manual markings were consistent with the automated measurement (<5°). At one month, the mean rotation recorded was 4,3° [0–29°]. The alignment was identical for 70 % (n=35) of the IOLs (≤5°). As for residual subjective astigmatism, the mean was 0.58 D. The mean visual acuity without correction was 8/10 and 55 % saw 10/10 without correction.

Refractive performance depends on preoperative measurement, correct alignment of the IOL and its stability in the bag. Our study shows the value of automated conjunctival registration in the determination of the intraoperative axis of alignment, even with an experienced surgeon. This precision is essential for a good refractive result, especially since residual astigmatism in the case of misalignment will increase with the power of the implant.

Our study shows excellent refractive results, regardless of the initial astigmatism, using automated alignment. Precision of toric implantation opens the way to toric multifocal implantation under the best conditions.