title: The impact of tear functions on visual outcome following keratoplasty in eyes with keratoconus.
abstract: BACKGROUND
  To investigate the impact of preoperative and postoperative tear functions on visual outcome and the recovery of visual function following keratoplasty in eyes with keratoconus.
  
  
  METHODS
  Twenty-five eyes of 25 consecutive patients (5 females, 20 males, mean age: 34.3 ± 15.8 years (range: 19-70 years) with keratoconus who underwent either penetrating keratoplasty (PKP) or deep anterior lamellar keratoplasty (DALK) were included in this prospective study. One patient who had a rejection episode during the follow-up period was excluded. All subjects underwent best corrected visual acuity (BCVA), corneal topography (refractive cylinder, surface regularity index: SRI and surface asymmetry index: SAI), Schirmer I test, tear film break-up time (BUT), corneal sensitivity, and fluorescein staining score measurements before as well as 1, 3, 6 and 12 months after keratoplasty. The relation between the tear functions and the duration until the achievement of maximum BCVA was also evaluated. Linear regression analysis was performed to study the statistical significance of the correlations and the time wise change of each examined parameter.
  
  
  RESULTS
  SRI, SAI, and BCVA significantly improved after keratoplasty. The postoperative corneal sensitivity was still significantly low even at 12 months postoperatively. Postoperative BCVA at 3, 6 months and maximum BCVA showed a significant linear negative correlation with the preoperative BUT (3 months; r = -0.461, p = 0.036, 6 months; r = -0.494, p = 0.023, maximum BCVA; r = -0.473, p = 0.030). The duration until the achievement of maximum BCVA showed a significant negative correlation with the preoperative Schirmer test (r = -0.429, p = 0.036). BCVA at 1 and 3 months postoperatively showed significant linear negative correlations with BUT value at the respective periods (1 month; r = -0.665, p = 0.0036, 3 months; r = -0.580, p = 0.0059).
  
  
  CONCLUSIONS
  Preoperative tear functions appeared to have an influence on postoperative BCVA and the duration of visual recovery in keratoconus patients undergoing keratoplasty. Postoperative tear film stability appears to play an important role for obtaining a better BCVA in the early postoperative period after keratoplasty.
authors.affiliation: Department of Ophthalmology, Social Insurance Chukyo Hospital, Nagoya-shi, Aichi, Japan.
authors.forename: Shuya
authors.initials: S
authors.lastname: Hara
authors.forename: Takashi
authors.initials: T
authors.lastname: Kojima
authors.forename: Murat
authors.initials: M
authors.lastname: Dogru
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Uchino
authors.forename: Eiki
authors.initials: E
authors.lastname: Goto
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Matsumoto
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Kawakita
authors.forename: Kazuo
authors.initials: K
authors.lastname: Tsubota
authors.forename: Jun
authors.initials: J
authors.lastname: Shimazaki
mesh_terms: D000328:Adult; D000368:Aged; D003315:Cornea / Q000503:physiopathology*; D019781:Corneal Topography; D016039:Corneal Transplantation; D005260:Female; D015590:Fluorophotometry; D006801:Humans; D007640:Keratoconus / Q000503:physiopathology / Q000601:surgery*; D015948:Keratoplasty, Penetrating; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D020127:Recovery of Function; D013666:Tears / Q000502:physiology*; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology*; D055815:Young Adult