title: Relationships between central tear film thickness and tear menisci of the upper and lower eyelids.
abstract: OBJECTIVE
  To investigate the relationship between central tear film thickness (TFT) and tear menisci of the upper and lower eyelids using real-time optical coherence tomography (OCT).
  
  
  METHODS
  Both eyes of healthy subjects were imaged with a real-time OCT to obtain height, curvature, and area of upper and lower tear menisci simultaneously. Central TFT was indirectly measured by calculating the difference between baseline measurements of the central corneal thickness plus tear film and the true corneal thickness obtained after instillation of artificial tears. Results from two normal blinks were obtained from one eye at each visit and repeated the next day.
  
  
  RESULTS
  The average central TFT was 3.4 +/- 2.6 microm. The upper tear meniscus curvature, height, and area were 239 +/- 112 microm, 268 +/- 68 microm, and 22,732 +/- 11,974 microm2 respectively. There were no significant differences in curvatures, heights, or areas between upper and lower tear menisci, nor were there any differences in measured variables between the two blinks at each visit or between the two repeated visits in the right and left eye groups (P > 0.05). The upper and lower tear menisci in each eye group on each day correlated strongly with curvature, height, and area (all P < or = 0.03). However, no tear meniscus variable was a significant predictor of TFT (all P > 0.44).
  
  
  CONCLUSIONS
  OCT is a promising tool in the measurements of TFT and dimensional variables of tear menisci. Upper and lower tear menisci have nearly identical dimensions.
authors.affiliation: Department of Ophthalmology, Schepens Eye Research Institute, Harvard Medical School, Boston, MA 02114, USA. jwang3@med.miami.edu
authors.forename: Jianhua
authors.initials: J
authors.lastname: Wang
authors.forename: James
authors.initials: J
authors.lastname: Aquavella
authors.forename: Jayachandra
authors.initials: J
authors.lastname: Palakuru
authors.forename: Suk
authors.initials: S
authors.lastname: Chung
authors.forename: Changyong
authors.initials: C
authors.lastname: Feng
mesh_terms: D000328:Adult; D001767:Blinking / Q000502:physiology; D005143:Eyelids / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D013666:Tears / Q000737:chemistry*; D041623:Tomography, Optical Coherence