title: [Influence of diameter of optical zone ablation on LASIK-induced higher order optical aberrations in myopia].
abstract: OBJECTIVE
  To analyze the effects of optical zone ablation diameter on LASIK-induced higher order optical aberrations in myopia.
  
  
  METHODS
  Four hundred and sixty-one eyes of 236 patients treated with LASIK for myopia were divided into high, moderate and low myopia group according to preoperative spherical equivalent diopter. In each group, eyes were divided into four subgroups according to optic zone ablation diameter. Before and after surgery 6 months, monochromatic wavefront aberrations of each eye were objectively measured using WASCA Analyzer Aberrometer. F test and q test were used to analyze the difference of total high order, horizontal coma, vertical coma, and spherical aberrations among four subgroups in each group at 4, 5, and 6 mm pupil size.
  
  
  RESULTS
  Before surgery no significant difference of higher order aberrations among four subgroups was found. After surgery, there was significant difference of total high order, and spherical aberrations among four subgroups. Total high order, and spherical aberrations in larger optical zone ablation diameter subgroup were significantly lower than that in smaller one. The difference was significant at 4, 5, and 6 mm pupil size in high myopia group, and 6 mm pupil size in low myopia group. At 6 mm pupil size, the difference was significant between each subgroup in high myopia group and subgroup I and subgroup IV in low myopia group. There was no significant difference of horizontal coma, and vertical coma aberrations among four subgroups.
  
  
  CONCLUSIONS
  Optical zone ablation diameter has influence on LASIK-induced higher order optical aberrations. Larger optical zone can decrease total higher order and spherical aberrations after LASIK. The effects are more significant in high myopia group than in low myopia group.
authors.affiliation: Department of Ophthalmology, Eye and ENT Hospital Affiliated to Fudan University, Shanghai 200031, China.
authors.forename: Zhen-ying
authors.initials: ZY
authors.lastname: Cheng
authors.forename: Ren-yuan
authors.initials: RY
authors.lastname: Chu
authors.forename: Xing-tao
authors.initials: XT
authors.lastname: Zhou
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000009:adverse effects / Q000379:methods*; D008297:Male; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D011183:Postoperative Complications / Q000517:prevention & control; D012030:Refractive Errors / Q000209:etiology / Q000503:physiopathology*