title: The effect of hinge position and depth plate on the rate of recovery of corneal sensation following LASIK.
abstract: OBJECTIVE
  To evaluate and compare the effect of hinge position and flap thickness on recovery rate of corneal sensation after (LASIK).
  
  
  METHODS
  Prospective, randomized clinical study.
  
  
  METHODS
  Forty eyes of 40 patients underwent LASIK to correct myopia ranging from -1.00 to -2.50 diopters. Corneal sensitivity was measured preoperatively and each month after surgery until recovery to preoperative level. The nasal-hinged ACS microkeratome (NH) with depth plates of 130 and 160 microm and the superior-hinged Hansatome microkeratome (SH) with depth plates of 160 and 180 microm were used for corneal flap creation. The eyes were divided into four groups according to the hinge position and depth plate (DP): group 1, NH and 130 microm DP; group 2, NH and 160 microm DP; group 3, SH and 160 microm DP; group 4, SH and 180 microm DP.
  
  
  RESULTS
  Corneal sensitivity returned to preoperative level after 3.7 (+/- 0.4), 4.4 (+/- 0.6), 5.4 (+/- 0.8), and 5.8 (+/- 0.9) months, respectively, in groups 1, 2, 3, and 4. Statistically significant differences were found between groups 1 and 2, but not between groups 3 and 4. Corneal sensitivity gradually returned to preoperative levels in all groups. Sensitivity of the hinge area was higher than other areas at every time point.
  
  
  CONCLUSIONS
  The results suggest that after LASIK, hinge position and flap thickness seem to be important factors in the rate of return of corneal sensitivity. A thin flap with a nasally placed hinge is associated with the most rapid recovery of corneal sensitivity.
authors.affiliation: Goiania Eye Institute, Goiania, Goias, Brazil. nassaral@zaz.com.br
authors.forename: Belquiz Amaral
authors.initials: BA
authors.lastname: Nassaralla
authors.forename: Stephen D
authors.initials: SD
authors.lastname: McLeod
authors.forename: Joel E
authors.initials: JE
authors.lastname: Boteon
authors.forename: João J
authors.initials: JJ
authors.lastname: Nassaralla
mesh_terms: D000328:Adult; D003315:Cornea / Q000502:physiology*; D003319:Corneal Stroma / Q000294:innervation / Q000601:surgery*; D019781:Corneal Topography; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000379:methods*; D008297:Male; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D011446:Prospective Studies; D020127:Recovery of Function / Q000502:physiology*; D012677:Sensation / Q000502:physiology*; D013524:Surgical Flaps; D014792:Visual Acuity