title: Tear film break-up time evaluated by real-time Hartmann-Shack wavefront sensing.
abstract: OBJECTIVE
  To develop a novel method for measuring tear break-up time (BUT) by continuously measuring higher order wavefront aberrations using a Hartmann-Shack (H-S) aberrometer.
  
  
  METHODS
  Wavefront aberrations up to the sixth order for a 4-mm pupil were measured in six eyes of six normal subjects using an H-S aberrometer. The aberrometry was performed once every second for up to 50 s under topical anesthesia. The sequence of the points was divided into two stages, and the BUT was defined as the wavefront border of the stages (WFBUT). The WFBUT was compared with the BUT by the conventional fluorescein method (FLBUT) or by the disruption of placid-ring images (PLBUT).
  
  
  RESULTS
  In three eyes, the WFBUT (average, 10.9 +/- 1.1 s) was shorter than the PLBUT (average, 17.5 +/- 2.5 s), while in the other three eyes the WFBUT (average, 21.5 +/- 2.2 s) was longer than PLBUT (average, 8.1 +/- 2.2 s). The FLBUT was shorter than WFBUT or PLBUT in most cases.
  
  
  CONCLUSIONS
  The tear break-up time measured by H-S aberrometer may be used as a practical measure of tear break-up.
authors.affiliation: Department of Applied Visual Science, Osaka University Graduate School of Medicine, Osaka, Japan.
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Mihashi
authors.forename: Yoko
authors.initials: Y
authors.lastname: Hirohara
authors.forename: Shizuka
authors.initials: S
authors.lastname: Koh
authors.forename: Sayuri
authors.initials: S
authors.lastname: Ninomiya
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Maeda
authors.forename: Takashi
authors.initials: T
authors.lastname: Fujikado
mesh_terms: D000328:Adult; D001251:Astigmatism / Q000175:diagnosis*; D003287:Contrast Media / Q000008:administration & dosage; D003941:Diagnostic Techniques, Ophthalmological; D019793:Fluorescein / Q000008:administration & dosage; D006801:Humans; D009883:Ophthalmic Solutions; D012016:Reference Values; D015203:Reproducibility of Results; D013666:Tears / Q000502:physiology*
chemical_list: D003287:Contrast Media; D009883:Ophthalmic Solutions; D019793:Fluorescein