[Toric lens implantation in cataract surgery: Automatic versus manual horizontal axis marking, analysis of 50 cases].

SUBJECT: The main objective of our study is to evaluate the contribution of automated conjunctival recognition in the alignment of toric implants by comparing the automatic alignment optimized with Callisto™ to the manual marking of the horizontal axis.

MATERIALS AND METHODS: We performed a prospective, descriptive, and monocentric study on patients undergoing cataract surgery with toric implantation (Asphina 709 Zeiss), operated by a surgeon with good experience in toricity, 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.

RESULTS: We included 50 eyes of 26 patients. The corrected mean 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 automatic measurement (<5°). At one month, the average rotation recorded was 4.3° [0°-29°]. The alignment was identical for 70 % (n=35) of the IOL (≤5°). As for residual subjective astigmatism, it was on average 0.58 D. The mean visual acuity without correction was 8/10 and 55 % had 10/10 without correction.

DISCUSSION: The refractive performance depends on the preoperative measurement, the correct alignment of the IOL and its stability in the bag. Our study shows the value of automatic conjunctival recognition in the determination of the axis of peroperative alignment, even in an experienced operator. This precision is essential for a good refractive result, especially since the residual astigmatism in case of misalignment will increase with the power of the implant.

CONCLUSION: Our study shows excellent refractive results, whatever the initial astigmatism, using the automatic alignment. The precision of the toric implantation opens the way to the toric multifocal implantation under the best conditions.