Toric lens implantation in cataract surgery: Automated versus manual horizontal axis marking, analysis of 50 cases

Summary

Subject

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.

Materials and methods

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.

Results

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.

Discussion

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.

Conclusion

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.

Introduction

Cataract surgery is the most commonly performed surgical procedure in France [1].

In the case of corneal astigmatism over 1 diopter (D), good distance vision requires glasses, despite correction of the spherical component of the refraction by an intraocular lens (IOL).

Correction of this astigmatism is possible at the time of the procedure and several options have already been available since the commercialization of toric platforms using virtual reality technology for alignment of the IOLs under the operating microscope.

We were interested in these technologies, which allow automated detection of the target axis of astigmatism, and studied their contribution in real life.

The primary goal of our study was to evaluate the role of conjunctival registration in the alignment of toric IOLs by a surgeon experienced in toric IOLs, comparing the axis generated automatically by conjunctival registration by Callisto^® (Zeiss) to the manual axis based on an initial marking of the 0–180° axis by marking pen in a seated position as the reference axis for the Callisto^®.