title: Predictive factor analysis for successful performance of iris recognition-assisted dynamic rotational eye tracking during laser in situ keratomileusis.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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 x 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 x 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.
authors.affiliation: Dr Agarwal's Eye Hospital and Eye Research Centre, 19 Cathedral Road, Chennai, India.
authors.forename: Gaurav
authors.initials: G
authors.lastname: Prakash
authors.forename: Dhivya
authors.initials: D
authors.lastname: Ashok Kumar
authors.forename: Amar
authors.initials: A
authors.lastname: Agarwal
authors.forename: Soosan
authors.initials: S
authors.lastname: Jacob
authors.forename: Yoga
authors.initials: Y
authors.lastname: Sarvanan
authors.forename: Athiya
authors.initials: A
authors.lastname: Agarwal
mesh_terms: D057128:Aberrometry; D000328:Adult; D003319:Corneal Stroma / Q000601:surgery; D019781:Corneal Topography; D005133:Eye Movements; D005260:Female; D006801:Humans; D007431:Intraoperative Complications; D007499:Iris Diseases / Q000175:diagnosis* / Q000209:etiology; D020731:Keratomileusis, Laser In Situ; D054018:Lasers, Excimer / Q000627:therapeutic use*; D008297:Male; D009216:Myopia / Q000601:surgery*; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology; D013524:Surgical Flaps; D014102:Torsion Abnormality / Q000175:diagnosis* / Q000209:etiology; D014792:Visual Acuity