Cyclotorsion in Patients in Upright versus Supine Position Undergoing Laser Vision Correction

Abstract

Purpose : There is variability in the amount and direction of cyclotorsion induced when a person moves from sitting to supine position. For laser vision correction, alignment is measured in the sitting position and surgery is performed in the supine position. In this retrospective study, we examine the amount and direction of cyclotorsion in sitting versus supine position in patients undergoing laser vision correction.

Methods : A retrospective chart review was done at Northwestern Medicine Department of Ophthalmology, Chicago, Illinois, USA of 893 eyes in 515 consecutive patients who underwent LASIK/PRK with successful iris registration. Amount and direction of cyclotorsion between sitting position versus supine position were analyzed. The amount and direction of cyclotorsion of each eye were quantified, and in patients undergoing bilateral procedures, concordance of cyclotorsion between right and left eye was assessed.

Results : 881 (98.6%) of the 893 eyes were found to have cyclotorsion with a mean of 2.88 degrees. 605 (67.8%) excyclotorted and 276 (30.9%) incyclotorted (p < 0.001). For a breakdown of degrees of cyclotorsion, see Figure 1. Average cyclotorsion in the right eye was 3.12 degrees and 2.52 in the left (p < 0.001). 361 patients underwent bilateral surgeries. 185 (51.2%) had concordant cyclotorsion (eyes rotate in same direction), while 166 (45.9%) had discordant cyclotorsion (eyes rotate in opposite directions).18 patients underwent subsequent retreatment with 14 (77.8%) demonstrating cyclotorsion in the same direction on both surgery days and 4 (22.2%) with cyclotorsion in different directions (p= 0.001).

Conclusions : Average cyclotorsion was less than 3 degrees, and when torsion was present about two-thirds of the eyes had excylotorsion. Amount and direction of cyclotorsion in one eye did not always correlate with the same amount and direction of cyclotorsion in the contralateral eye. Understanding that there is variability in cyclotorsion is important in surgeries such as wavefront guided LASIK/PRK where identification of and correction for cyclotorsion can impact visual results.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

 

Figure 1. Histogram of the degrees of cyclotorsion in eyes with wavefront guided LASIK/PRK with successful iris registration.