title: Higher order aberrations of the corneal surface after laser subepithelial keratomileusis.
abstract: OBJECTIVE
  To evaluate the changes of higher order aberrations (HOAs) before and after laser subepithelial keratomileusis (LASEK) and to analyze the influence of tear film instability on HOAs of the corneal surface after LASEK.
  
  
  METHODS
  In this cross-sectional study, 31 patients who underwent LASEK were divided into dry eye (16 patients, 32 eyes) and non-dry eye groups (15 patients, 30 eyes). Uncorrected distance visual acuity, spherical equivalent refraction, ablation depth, tear film parameters and Ocular Surface Disease Index (OSDI) questionnaire scores were evaluated in both groups. Total HOA root mean square (RMS), third-order coma, third-order trefoil and fourth-order spherical aberration (SA) of the corneal surface immediately and at 10 seconds after blinking were measured before and after surgery.
  
  
  RESULTS
  The total HOA RMS, coma, trefoil and SA significantly increased after LASEK compared with preoperative values in both groups. In the dry eye group, total HOA RMS, coma and trefoil significantly increased except for SA at 10 seconds after blinking compared with those measured immediately after blinking. In addition, the changes of total HOA RMS, coma and trefoil were negatively correlated with tear film break-up time (R = -0.420, -0.473 and -0.439, respectively), but positively correlated with OSDI score (R = 0.433, 0.499 and 0.532, respectively). In the non-dry eye group, there were no significant differences between HOAs measured at 10 seconds after blinking and those measured immediately after blinking.
  
  
  CONCLUSIONS
  The HOAs including coma, trefoil and SA significantly increased after LASEK. The tear film instability in the dry eye can be associated with more deterioration of the optical quality after LASEK, due to more significant increase of total HOA RMS, coma and trefoil.
authors.affiliation: Department of Ophthalmology and Research Institute of Medical Sciences, Chonnam National University Hospital, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Hyun Ho
authors.initials: HH
authors.lastname: Jung
authors.affiliation: Department of Ophthalmology and Research Institute of Medical Sciences, Chonnam National University Hospital, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Yong Sok
authors.initials: YS
authors.lastname: Ji
authors.affiliation: Department of Ophthalmology and Research Institute of Medical Sciences, Chonnam National University Hospital, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Han Jin
authors.initials: HJ
authors.lastname: Oh
authors.affiliation: Department of Ophthalmology and Research Institute of Medical Sciences, Chonnam National University Hospital, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Kyung Chul
authors.initials: KC
authors.lastname: Yoon
mesh_terms: D000328:Adult; D003315:Cornea / Q000503:physiopathology*; D057108:Corneal Wavefront Aberration / Q000209:etiology* / Q000503:physiopathology; D003430:Cross-Sectional Studies; D015352:Dry Eye Syndromes / Q000503:physiopathology*; D005260:Female; D006801:Humans; D049008:Keratectomy, Subepithelial, Laser-Assisted / Q000009:adverse effects*; D054018:Lasers, Excimer / Q000627:therapeutic use*; D008297:Male; D011795:Surveys and Questionnaires; D013666:Tears / Q000502:physiology*; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult
keywords: Higher order aberration; Laser subepithelial keratomileusis; Tear film instability