title: Lysosomal hydrolase staining of conjunctival impression cytology specimens in keratoconus.
abstract: OBJECTIVE
  This study sought to assess the feasibility of impression cytology for the determination of conjunctival intracellular lysosomal hydrolase (acid esterase) levels in patients with keratoconus.
  
  
  METHODS
  Twenty-two patients with keratoconus currently enrolled in the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study and 22 age-and sex-similar controls underwent impression cytology. Samples were collected from each subject and control pair on the same day. The cells of the respective specimens were fixed immediately and were stained for acid esterase with use of identical batches of fixatives and stains. After staining, the specimens were cleared in xylene for mounting in synthetic resin on glass slides. The acid esterase staining intensity of each specimen was quantified as the percentage of light transmitted with use of an image analysis system (Zeiss). Multiple cells from each specimen were analyzed for each sample collected.
  
  
  RESULTS
  Mixed model analysis was used to account for the subject-control pairings and for the multiple cells from each sample. With this method, the mean light transmission for normal controls (mean = 63.0; standard error [SE] = 3.0) was highly statistically significantly different from that for the keratoconus subjects (mean = 52.4; SE = 3.0) (two-tailed p= 0.0032).
  
  
  CONCLUSIONS
  This study establishes the feasibility of adapting an acid esterase staining technique to conjunctival cells collected via impression cytology. Higher levels of lysosomal enzyme staining in patients with keratoconus have been previously reported by other investigators using full-thickness conjunctival specimens. We also demonstrate the value of using objective microspectrophotometry in measuring lysosomal enzyme staining with impression cytology specimens.
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, 1855 West Taylor Street, Chicago, IL 60612, USA.
authors.forename: Joanne F
authors.initials: JF
authors.lastname: Shen
authors.forename: Timothy T
authors.initials: TT
authors.lastname: McMahon
authors.forename: E Lillian
authors.initials: EL
authors.lastname: Cheng
authors.forename: Joel
authors.initials: J
authors.lastname: Sugar
authors.forename: Beatrice Y J T
authors.initials: BY
authors.lastname: Yue
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Anderson
authors.forename: Carolyn
authors.initials: C
authors.lastname: Begley
authors.forename: Jie
authors.initials: J
authors.lastname: Zhou
mesh_terms: D000115:Acetylesterase / Q000378:metabolism*; D000328:Adult; D003228:Conjunctiva / Q000201:enzymology* / Q000473:pathology; D003581:Cytodiagnosis / Q000379:methods; D004848:Epithelium / Q000201:enzymology / Q000473:pathology; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000175:diagnosis / Q000201:enzymology*; D008247:Lysosomes / Q000201:enzymology*; D008297:Male; D008875:Middle Aged; D013194:Staining and Labeling / Q000379:methods
chemical_list: D000115:Acetylesterase