Predictive Factor Analysis for Successful Performance of Iris Recognition-Assisted Dynamic Rotational Eye Tracking during Laser In Situ Keratomileusis

Purpose To analyze the predictive factors associated with success of iris recognition and dynamic rotational eye tracking on a laser in situ keratomileusis (LASIK) platform with active assessment and correction of intraoperative cyclotorsion. Design Interventional case series. Methods Two hundred seventy-five eyes of 142 consecutive candidates underwent LASIK with attempted iris recognition and dynamic rotational tracking on the Technolas 217z100 platform (Techolas Perfect Vision, St Louis, Missouri, USA) at a tertiary care ophthalmic hospital. The main outcome measures were age, gender, flap creation method (femtosecond, microkeratome, epi-LASIK), success of static rotational tracking, ablation algorithm, pulses, and depth; preablation and intraablation rotational activity were analyzed and evaluated using regression models. Results Preablation static iris recognition was successful in 247 eyes, without difference in flap creation methods ( P = .6). Age (partial correlation, −0.16; P = .014), amount of pulses (partial correlation, 0.39; P = 1.6 × 10−8 ), and gender ( P = .02) were significant predictive factors for the amount of intraoperative cyclodeviation. Tracking difficulties leading to linking the ablation with a new intraoperatively acquired iris image were more with femtosecond-assisted flaps ( P = 2.8 × 10−7 ) and the amount of intraoperative cyclotorsion ( P = .02). However, the number of cases having nonresolvable failure of intraoperative rotational tracking was similar in the 3 flap creation methods ( P = .22). Conclusions Intraoperative cyclotorsional activity depends on the age, gender, and duration of ablation (pulses delivered). Femtosecond flaps do not seem to have a disadvantage over microkeratome flaps as far as iris recognition and success of intraoperative dynamic rotational tracking is concerned.