title: Laser in situ keratomileusis for high myopia using a small ablation zone and large aspheric transition zone.
abstract: OBJECTIVE
  To evaluate the efficacy and predictability of laser in situ keratomileusis (LASIK) using the Nidek NAVEX system with a small ablation (optical, OZ) zone and a large aspheric transition zone (OATz).
  
  
  METHODS
  We report a prospective nonrandomized study of LASIK for high myopia using a small ablation in 23 eyes of 18 patients. The optical zone was between 3 and 3.8 mm and transition zone (TZ) was between 7 and 7.8 mm. Preoperative examination included best-spectacle corrected visual acuity (BSCVA), refraction, and corneal topography. All eyes were measured by the Nidek OPD-Scan and data were imported to FinalFit software. Aspheric profile (OATz) numbers 5 to 7 were used. BSCVA, uncorrected spectacle visual acuity (UCVA), refraction, and subjective evaluation of glare and night vision by questionnaire were recorded after surgery.
  
  
  RESULTS
  At baseline, mean spherical equivalent refraction was -7.03 +/- 2.39 D (range -5.50 to -15.50 D). Postoperative UCVA was better than 20/25 in 95.65% of eyes 3 months after LASIK. Postoperative refraction was within +/- 0.50 D of emmetropia in 91.3% of eyes and within +/- 1.00 D in all eyes. No eye lost lines of BSCVA; 52.17% of eyes gained 1 line and 13.04% of eyes gained 2 lines. No patient reported significant glare or night vision problems on subjective questionnaire.
  
  
  CONCLUSIONS
  LASIK with a small ablation (optical) zone and high aspheric transition zone using the Nidek NAVEX system was effective, predictable, and relatively safe for correction of high myopia.
authors.affiliation: Department of Ophthalmology, Ramathibodi Hospital School of Medicine, Mahidol University, Bangkok, Thailand. teawt@mahidol.ac.th
authors.forename: Anun
authors.initials: A
authors.lastname: Vongthongsri
authors.forename: Nutharin
authors.initials: N
authors.lastname: Phusitphoykai
authors.forename: Tulaya
authors.initials: T
authors.lastname: Tungsiriput
mesh_terms: D000328:Adult; D003319:Corneal Stroma / Q000601:surgery*; D019781:Corneal Topography; D019466:Glare; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000295:instrumentation / Q000379:methods*; D008875:Middle Aged; D009216:Myopia / Q000601:surgery*; D017060:Patient Satisfaction; D011183:Postoperative Complications; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology; D015203:Reproducibility of Results; D012449:Safety; D011795:Surveys and Questionnaires; D014792:Visual Acuity / Q000502:physiology