title: Comparison of higher-order aberrations after LASEK with a 6.0 mm ablation zone and a 6.5 mm ablation zone with blend zone.
abstract: OBJECTIVE
  To compare the higher-order aberrations (HOAs) after laser-assisted subepithelial keratectomy (LASEK) using a conventional optical zone and a larger zone with a blend zone.
  
  
  METHODS
  Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea.
  
  
  METHODS
  In this prospective study, 19 patients with a manifest refraction of -3.00 to -8.25 diopters (D) were treated with LASEK using a conventional (6.0 mm) optical zone in 1 eye and a larger (6.5 mm) zone with 8.0 mm blend zone in the other eye. The patients were followed for 3 months. Pupil size, best corrected visual acuity (BCVA), uncorrected visual acuity (UCVA), manifest refraction, corneal topography, pachymetry, and wavefront aberration were examined preoperatively; BCVA, UCVA, manifest refraction, and wavefront aberration were measured 1 and 3 months postoperatively. The Hartmann-Shack aberrometer (WaveScan(R), Visx) was used to measure the overall wavefront aberrations in scotopic pupils.
  
  
  RESULTS
  There were no significant differences in preoperative pupil size, BCVA, UCVA, and manifest refraction between the 2 groups or in postoperative BCVA, UCVA, and refraction. Higher-order aberrations increased at 1 and 3 months in both eyes compared with preoperatively. At 3 months, in a scotopic pupil, the mean root-mean-square wavefront error of the HOAs was 0.41 +/- 0.14 in the eyes treated with the larger optical zone and 0.61 +/- 0.28 in those treated with the conventional optical zone. There was a significant difference between optical zones (P =.006). The difference was more pronounced in the treatment of myopia greater than -5.0 D (P =.001).
  
  
  CONCLUSIONS
  In the scotopic condition, HOAs after LASEK using a large optical zone with blend zone ablation were smaller than those associated with conventional ablation zone treatment. The larger zone with blend zone treatment may be a good surgical alternative for better visual outcomes in scotopic conditions.
authors.affiliation: Department of Ophthalmology, Yonsei Institute of Vision Research, Yonsei University College of Medicine, Seoul, South Korea.
authors.forename: Kyoung Yul
authors.initials: KY
authors.lastname: Seo
authors.forename: Jae Bum
authors.initials: JB
authors.lastname: Lee
authors.forename: Jimmy Jaeyoung
authors.initials: JJ
authors.lastname: Kang
authors.forename: Eun Suk
authors.initials: ES
authors.lastname: Lee
authors.forename: Eung Kweon
authors.initials: EK
authors.lastname: Kim
mesh_terms: D000328:Adult; D003315:Cornea / Q000601:surgery*; D019781:Corneal Topography; D003623:Dark Adaptation; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000009:adverse effects* / Q000379:methods*; D011446:Prospective Studies; D011680:Pupil / Q000502:physiology; D012029:Refraction, Ocular / Q000502:physiology; D012030:Refractive Errors / Q000209:etiology*; D054140:Refractive Surgical Procedures; D014786:Vision Disorders / Q000209:etiology*; D014792:Visual Acuity / Q000502:physiology