Postoperative Refractive and Visual Acuity Outcomes Using Manual Ink Markings versus Callisto Markerless System for Toric Intraocular Lens Implantation

Abstract

Purpose : The effective power of a toric intraocular lens (IOL) is reduced by 3% for each degree of IOL misalignment. The purpose of the current study is to compare the refractive and visual acuity outcomes following cataract surgery with toric IOL implantation using manual ink markings versus the Callisto markerless system to define the axis for IOL alignment.

Methods : This retrospective study included consecutive patients without vision limiting ocular pathology who underwent cataract surgery with toric IOL implantation by a single surgeon at an academic medical center from July 2015 - October 2016. Keratometry was performed preoperatively with IOLMaster 5 or 700 (Carl Zeiss Meditec) on 25 eyes from 23 patients for whom the reference and target axes were marked manually with ink and 14 eyes from 12 patients for whom the target axis was defined with the Callisto markerless system. IOL selection was calculated using the Holladay 2 formula. An AcrySof Toric (Alcon) IOL was implanted in all patients. Primary outcome measures included the numerical error (difference between predicted and actual spherical equivalents [SE]) and uncorrected distance visual acuity (UCVA), which were measured 1 month postoperatively.

Results : The mean numerical error was 0.46 ±0.60 D in the group whose reference and target axes were marked manually with ink compared to 0.179±0.20 D in the Callisto group (p = 0.13). While 32% of eyes with manual markings had an absolute numerical error of ≥0.5D, only 7% of eyes in the Callisto group had an absolute numerical error ≥0.5D (p=0.08). The proportion of eyes with an absolute numerical error of <0.5 D was 68% in the manual marking group compared to 93% in the Callisto group (p=0.08). With manual marking and Callisto, 56% and 57.1% of eyes, respectively, had an UCVA of 20/20 (p=0.89).

Conclusions : Results of the current study suggest a trend toward better refractive outcomes with the Callisto markerless system compared to manual ink markings. No difference in UCVA outcome was identified between the two groups. These findings warrant further investigation in prospective randomized studies with larger sample sizes.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.