Digital versus slit-beam marking for toric intraocular lenses in cataract surgery

Purpose To compare the visual outcomes of digital and slit-beam manual marking for toric intraocular lenses (IOL) in cataract surgery. Setting Single-center, Beijing Tongren Hospital, China. Design Retrospective study. Methods All patients with cataracts and regular corneal astigmatism greater than 0.75 diopters (D) underwent cataract surgery and astigmatism correction between June 2019 and June 2020. To mark the target axis of the toric IOL and the location of the incision, intraoperative digital marking was used by Callisto eye image-guided system in one group, while preoperative manual slit-beam marking was used in the other group. Uncorrected and best-corrected spectacle visual acuity, refraction, toric IOL axis, total higher order aberrations, coma, spherical aberration, and trefoil were evaluated at 1, 4, and 12 weeks postoperatively. Results Seventy-two eyes of 58 patients were included. At 3 months after surgery, the mean residual refractive cylinder was 0.42 +/- 0.45D in the digital group and 0.39 +/- 0.40D in the manual group (P = 0.844). There were no significant differences between groups in spherical equivalent refraction, uncorrected and best-corrected spectacle visual acuity, or the parameters of vector analysis. All toric IOL alignment errors were within 10 degrees of the intended axis, and among them, about 42% of eyes in the digital group and 61% of eyes in the manual group had a rotation of 0-2 degrees (P = 0.038). Trefoil in the manual group decreased postoperatively compared with the digital group (P = 0.012). Other aberration analyses did not reveal any statistical differences between groups. Conclusions Accurate slit-beam manual marking and digital image-guided marking are equally effective for toric IOL alignment.