Evaluation of Markerless Alignment System for Toric IOLs
To compare the efficacy of aligning Toric IOLs using a corneal ink mark with the Callisto markerless system from Carl Zeiss Meditec.
A prospective non randomized trial of patients with astigmatism presenting for cataract surgery. This is a single centre, single surgeon, single IOL study. Patients prior to Aug 2014 had corneal ink marks used to align the Toric IOL and for patients after that date the Callisto system for Toric IOL alignment was utilized. Post operative refractions were analyzed to compare the efficacy of these two methods in correcting astigmatism.
507 cases from the ink marking group and 161 cases from the Callisto markerless group were compared. There was no difference in the mean or standard deviation of residual astigmatic refractive error. However, in the ink marking group 6.0% had more than 0.5 diopters of astigmatism on refraction post-op compared with 0.6% in the Callisto group.
Both ink marking and digital markerless methods are accurate means of Toric IOL alignment. The Callisto group had no outliers and could be considered more accurate.