title: Effect of corneal drying on optical coherence tomography.
abstract: OBJECTIVE
  To determine the effect of corneal drying on the outcome of optical coherence tomography (OCT).
  
  
  METHODS
  Cohort study.
  
  
  METHODS
  Seventeen normal participants (mean age, 39+/-12 years).
  
  
  METHODS
  Subjects underwent a series of peripapillary circular StratusOCT scans (version 3.0; Carl Zeiss Meditec, Inc., Dublin, CA) in a randomly selected eye. Baseline scan sets were acquired, and thereafter, blinking was prevented by taping the eyelid. Eyelid taping was immediately followed by 6 to 8 serial scan sets, each separated by 20 seconds. After removing the eyelid tape, 3 additional scans were acquired at 1, 2, and 4 minutes of blinking freely.
  
  
  METHODS
  The analyzed outcome measures were scan quality as defined by signal-to-noise ratio (SNR) and signal strength (SS) provided by the built-in OCT software and mean nerve fiber layer (NFL) thickness.
  
  
  RESULTS
  Significant reductions in SNR, SS, and NFL were noted at each scanning point in the drying phase (for each, P<0.015, paired t test) except for NFL thickness measurements acquired at 140 and 160 seconds. The reduction in NFL thickness exceeded the 95% confidence limit of the reported reproducibility error of StratusOCT after 15 seconds of corneal drying. After 1 and 2 minutes of blinking freely, there was still a significant reduction in NFL thickness compared with the baseline value, which was no longer evident at the 4-minute scan.
  
  
  CONCLUSIONS
  Corneal dryness affects OCT scan quality and measured NFL thickness after a short exposure time. It is recommended to instruct those who are scanned to blink frequently or to instill artificial tears.
authors.affiliation: UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Sciences Research Center, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Stein
authors.affiliation: UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Sciences Research Center, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
authors.forename: Gadi
authors.initials: G
authors.lastname: Wollstein
authors.affiliation: UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Sciences Research Center, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ishikawa
authors.affiliation: Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts.
authors.forename: Ellen
authors.initials: E
authors.lastname: Hertzmark
authors.affiliation: UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Sciences Research Center, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Noecker
authors.affiliation: UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Sciences Research Center, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
authors.forename: Joel S
authors.initials: JS
authors.lastname: Schuman
mesh_terms: D000328:Adult; D003315:Cornea / Q000503:physiopathology*; D015352:Dry Eye Syndromes / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D009412:Nerve Fibers / Q000473:pathology*; D009900:Optic Nerve / Q000503:physiopathology*; D011446:Prospective Studies; D012165:Retinal Ganglion Cells / Q000473:pathology*; D017603:Signal Detection, Psychological; D041623:Tomography, Optical Coherence / Q000592:standards*