title: Iris registration in wavefront-guided LASIK to correct mixed astigmatism.
abstract: OBJECTIVE
  To investigate the predictability, safety, and efficiency of wavefront-guided laser in situ keratomileusis (LASIK) with iris-registration technology to correct mixed astigmatism.
  
  
  METHODS
  Vision correction center, Alexandria, Egypt.
  
  
  METHODS
  This retrospective double-blind study included randomly selected patients with mixed astigmatism who sought laser refractive surgery. Patients were divided equally into 3 groups and treated with conventional LASIK and manual marking, wavefront-guided LASIK and manual marking, or wavefront-guided LASIK with iris registration (LASIK+IR group). Eyes were analyzed preoperatively and up to 3 months postoperatively.
  
  
  RESULTS
  The LASIK+IR group had better postoperative uncorrected visual acuity (100% 20/30 or better; 90% 20/20 or better; 20% 20/16 or better) than the other groups and did not lose preoperative best spectacle-corrected visual acuity, unlike the other groups. This group also had the highest percentage of eyes that gained lines of acuity (20% 1 line; 10% 2 lines). The LASIK+IR group had the highest predictability of spherical refraction (80% within +/-0.50 diopter [D]; 100% within +/-1.00 D [P<.05] and the highest predictability of cylinder refraction. The LASIK+IR eyes had a significantly smaller increase postoperatively in coma, trefoil, and secondary astigmatism. There was no significant difference between groups in spherical aberration or quadrafoil. The LASIK-IR group had the most improvement in scotopic contrast sensitivity (P<.05).
  
  
  CONCLUSIONS
  Wavefront-guided LASIK with iris registration was more predictable, safe, and efficient than conventional or wavefront-guided LASIK with manual marking in correcting mixed astigmatism. Further studies are needed to confirm these results.
authors.affiliation: Tanta University Khalifa, Tanta, Egypt. mounirkhalifa@yahoo.com
authors.forename: Mounir
authors.initials: M
authors.lastname: Khalifa
authors.forename: Mohamed
authors.initials: M
authors.lastname: El-Kateb
authors.forename: Mohamed Shafik
authors.initials: MS
authors.lastname: Shaheen
mesh_terms: D000328:Adult; D001251:Astigmatism / Q000503:physiopathology / Q000601:surgery*; D015350:Contrast Sensitivity / Q000502:physiology; D003315:Cornea / Q000503:physiopathology / Q000601:surgery; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007498:Iris; D020731:Keratomileusis, Laser In Situ / Q000379:methods*; D054018:Lasers, Excimer / Q000627:therapeutic use*; D008297:Male; D012189:Retrospective Studies; D014792:Visual Acuity / Q000502:physiology