title: Polycarbonate membrane impression cytology: evidence for fluorescein staining in normal and dry eye corneas.
abstract: OBJECTIVE
  Corneal impression cytology is usually performed with mixed cellulose ester membranes and a limited array of stains. A method using polycarbonate membrane air-dried preparations led to the discovery of fluorescein staining in cells from patients with and without dry eye disease and a membrane-induced defect that was not due to cell removal.
  
  
  METHODS
  Impressions after fluorescein installation were performed using polycarbonate and mixed cellulose ester membranes with rapid staining protocols for Diff-Quick as well as haematoxylin and eosin stains. Prior to staining the air-dried material was examined for fluorescence.
  
  
  RESULTS
  Epithelia of both normal and dry eye corneas retained fluorescence from clinical instillation of fluorescein. Corneal defects created by the polycarbonate membrane could not be explained by membrane-induced cell removal. After rapid staining, polycarbonate membranes revealed less background, dissolved easily prior to coverslip application, but showed lower cellular yield compared with the mixed cellulose membranes.
  
  
  CONCLUSIONS
  Polycarbonate membrane impression cytology enables immediate assessment with rapid stains. Topically applied fluorescein penetrates corneal epithelial cells in both normal and dry eye patients. Cells fluoresce on the cytology membranes. The impression-induced defect on the cornea is not due to cell stripping and may represent removal of mucins.
authors.affiliation: Jules Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Sumeer
authors.initials: S
authors.lastname: Thinda
authors.forename: Puneeta K
authors.initials: PK
authors.lastname: Sikh
authors.forename: Lawrence M
authors.initials: LM
authors.lastname: Hopp
authors.forename: Ben J
authors.initials: BJ
authors.lastname: Glasgow
mesh_terms: D000328:Adult; D003584:Cytological Techniques; D015352:Dry Eye Syndromes / Q000473:pathology*; D019573:Epithelium, Corneal / Q000473:pathology*; D005260:Female; D019793:Fluorescein; D005456:Fluorescent Dyes; D006801:Humans; D008297:Male; D011076:Polycarboxylate Cement; D013194:Staining and Labeling / Q000379:methods; D055815:Young Adult
chemical_list: D005456:Fluorescent Dyes; D011076:Polycarboxylate Cement; C005506:polycarbonate; D019793:Fluorescein