title: Spectral-domain optical coherence tomography study on dynamic changes of human tears after instillation of artificial tears.
abstract: OBJECTIVE
  To analyze in vivo the dynamic changes induced by different artificial tears (ATs) in the precorneal tear film (PCTF) and lower tear meniscus (LTM) by using spectral-domain (SD) anterior segment optical coherence tomography (OCT).
  
  
  METHODS
  We prospectively examined 42 normal human eyes by using SD-OCT imaging. On the day before OCT imaging, all enrolled subjects were evaluated for abnormalities of ocular surface. All tear film images were obtained before and after instillation of three different types of ATs (mucomimetic, lipid-based, and saline) in five serial scans: immediately (within 30 seconds), at the first, fifth, 10th, and 20th minute. Subjects received a drop of 35 μL in one randomly selected eye. All examinations were conducted in the same conditions of temperature, brightness, humidity, and time of day.
  
  
  RESULTS
  Changes in the morphological pattern of both LTM and PCTF were associated with the type of artificial tear instilled on the ocular surface. Similarly, the radius of curvature (rc), the height (h), and the depth (d) showed dynamic variations depending on treatment. Although by the 20th minute, both h and d returned to baseline values in all groups, a significant difference in rc (compared with baseline) was detected for mucomimetic ATs (P = 0.04) and lipid ATs (P = 0.02).
  
  
  CONCLUSIONS
  Spectral-domain OCT imaging has preliminarily proved to be a noninvasive tool to evaluate, in real time, the different changes induced by ATs instillation. An important stride in understanding the clinical response to various tear substitutes can be achieved by this objective and quantitative approach.
authors.affiliation: Department of Surgical Sciences, Eye Clinic, University of Cagliari, Cagliari, Italy.
authors.forename: Pietro Emanuele
authors.initials: PE
authors.lastname: Napoli
authors.affiliation: Department of Surgical Sciences, Eye Clinic, University of Cagliari, Cagliari, Italy.
authors.forename: Giovanni Maria
authors.initials: GM
authors.lastname: Satta
authors.affiliation: Department of Surgical Sciences, Eye Clinic, University of Cagliari, Cagliari, Italy.
authors.forename: Franco
authors.initials: F
authors.lastname: Coronella
authors.affiliation: Department of Surgical Sciences, Eye Clinic, University of Cagliari, Cagliari, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Fossarello
mesh_terms: D000328:Adult; D003315:Cornea / Q000033:anatomy & histology / Q000187:drug effects*; D005260:Female; D015590:Fluorophotometry; D005583:Fourier Analysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D009883:Ophthalmic Solutions / Q000008:administration & dosage*; D011446:Prospective Studies; D013666:Tears / Q000737:chemistry* / Q000502:physiology; D041623:Tomography, Optical Coherence
chemical_list: D009883:Ophthalmic Solutions
keywords: OCT; artificial tears; ocular surface; tear film; tear meniscus