June 2017
Volume 58, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2017
Comparison of Manual Ink Markings to the Callisto Markerless System for Defining the Reference Axis in Anticipation of Toric IOL Implantation
Author Affiliations & Notes
  • Hans Andrews
    Penn State College of Medicine, Hershey, Pennsylvania, United States
  • Deepak Sambhara
    Penn State College of Medicine, Hershey, Pennsylvania, United States
  • Shruti Sudhakar
    Penn State College of Medicine, Hershey, Pennsylvania, United States
  • Ingrid U Scott
    Penn State College of Medicine, Hershey, Pennsylvania, United States
  • Seth Pantanelli
    Penn State College of Medicine, Hershey, Pennsylvania, United States
  • Footnotes
    Commercial Relationships   Hans Andrews, None; Deepak Sambhara, None; Shruti Sudhakar, None; Ingrid Scott, None; Seth Pantanelli, None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science June 2017, Vol.58, 1156. doi:
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      Hans Andrews, Deepak Sambhara, Shruti Sudhakar, Ingrid U Scott, Seth Pantanelli; Comparison of Manual Ink Markings to the Callisto Markerless System for Defining the Reference Axis in Anticipation of Toric IOL Implantation. Invest. Ophthalmol. Vis. Sci. 2017;58(8):1156.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : For each degree of misalignment, the effective power of a toric intraocular lens (IOL) is reduced by 3%. The purpose of this study is to compare manual ink markings and the Callisto® markerless system (Carl Zeiss Meditech, Inc.) with regards to defining the reference axis for the alignment of toric IOLs.

Methods : This consecutive case series included all eyes that underwent cataract extraction by a single surgeon between January 7th and November 17th, 2016, and for which a toric IOL implantation or a limbal relaxing incision was performed. For each eye, a reference image was captured preoperatively using the IOLMaster 700. Just prior to surgery, with the patient upright, the limbus was hand marked with an ink pen at the 3 and 9 o’clock positions. In the operating room, registration with the previously captured reference image was performed. A screenshot was captured that showed both the manual markings and the digitally defined reference axis. Using a digital protractor, the difference between the manually defined reference axis and the Callisto defined reference axis was measured.

Results : Thirty-four eyes of twenty-four patients were included in the study. The average absolute difference between the Callisto defined reference axis and the manually defined reference axis was 2.87 ± 2.45 (SD) degrees (range 0.2 to 8.4 degrees). Ten eyes (28%) had less than 1 degree difference, 8 (23%) differed between 1 and 2 degrees, 11 (31%) between 2 and 5 degrees, and 6 (18%) differed by more than 5 degrees.

Conclusions : There is no universally accepted method for defining the correct reference axis prior to cataract surgery. However, it is plausible that digitally defined registration is more accurate than manual marking. For nearly one-fifth of the eyes in the current study, the difference between the two methods was more than 5 degrees, suggesting that use of a digitally defined reference axis could translate to significant improvement in the correction of astigmatism. Studies evaluating refractive outcomes that compare the two marking methods are needed to further evaluate the potential benefits of the Callisto system.

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

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