Abstract
Purpose :
To determine the accuracy of two axis-marking methods for toric intraocular lens (IOL) implantation, one picture-assisted approach based on scleral vessel vectors, and the other based on a self-leveling device for manual marking.
Methods :
This retrospective single-center study involved 60 eyes of 51 participants, who underwent phacoemulsification with toric IOL implantation. In all eyes, preoperative markings were made in a seated position either manually via a self-leveling, 1-step corneal marker (RoboMarker, Surgilum, Wilmington, NC, USA), and digitally on slit-lamp photographs, defining scleral vessels as landmarks.
For the latter, a slit-lamp photograph was taken, which was digitally edited as follows: a circular angle overlay was superimposed on the photograph and centered on the pupillary center, with a diameter of the largest white-to-white distance. Remarkable configurations of scleral vessels were assessed and a vector was drawn from the center of the overlay, resulting in an axis degree. A minimum of three vectors was required for each image.
Intraoperatively, guided by a colored printout (Figure 1), the marked configurations of scleral vessels were firstly relocated in the supine position of the patient, and marked with an ink augmented cannula. Secondly, taking these landmarks into account, a Mendez ring was put on the eye aligned concordantly to the respective axis degrees (Figure 2). Thirdly, the target axis was determined and marked with the ink augmented cannula.
The axis of IOL alignment at the end of surgery was determined from high resolution, intraoperative footage from a microscope-integrated camera and the axis-marking error served as an outcome measurement for both marking techniques. The endpoint was the alignment of the lens at the end of surgery.
Results :
The average axis-marking error was 2.5 ±1.9 degrees for picture-assisted marking, which was significantly less than that of the self-leveling corneal marker, being 5.4 ±4.4 degrees.
Conclusions :
We could validate that scleral vessel vector marking is not inferior but leads to more accurate toric IOL alignments, when compared to a manual self-leveling device for 1-step marking.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.