title: Tear sample collection using cellulose acetate absorbent filters.
abstract: OBJECTIVE
  To assess the use of cellulose acetate filter rods as a technique for tear collection.
  
  
  METHODS
  The cellulose acetate rod (CR) was compared with the 'standard' glass capillary tube (CT), in a series of experiments, to assess: sample collection by collected volume size; the effect of tear stimulation on total tear protein concentration and major tear protein concentrations; and technique invasiveness.
  
  
  RESULTS
  No difference was found in concentrations for total protein, IgA (secretory immunoglobulin A), lactoferrin and lysozyme (p > 0.05) with no clinically significant increase in serum albumin to show serum leakage. Sample volume was higher for CR (p < 0.005) and sample volume increased for stimulated collection with CR (p = 0.001). Dilution effect of a stimulated sample size was reliably shown only with CR (r = -0.66, p = 0.011). Using bovine albumin standard with CR and CT, a smaller sample volume (p < 0.001) and a higher protein concentration (p < 0.001) were extracted with CR.
  
  
  CONCLUSIONS
  The cellulose rod offers a suitable alternative to the glass CT. It is able to quickly absorb a sample, allowing use for a wide range of sample sizes, while being minimally invasive.
authors.affiliation: School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff CF24 4LU, UK. EsmaeelpourM@cf.ac.uk
authors.forename: Marieh
authors.initials: M
authors.lastname: Esmaeelpour
authors.forename: Jun
authors.initials: J
authors.lastname: Cai
authors.forename: Patrick
authors.initials: P
authors.lastname: Watts
authors.forename: Mike
authors.initials: M
authors.lastname: Boulton
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Murphy
mesh_terms: D000328:Adult; D002482:Cellulose / Q000031:analogs & derivatives; D005136:Eye Proteins / Q000032:analysis*; D005260:Female; D006801:Humans; D007071:Immunoglobulin A, Secretory / Q000378:metabolism; D007781:Lactoferrin / Q000378:metabolism; D008297:Male; D009113:Muramidase / Q000378:metabolism; D013048:Specimen Handling / Q000295:instrumentation / Q000379:methods*; D013666:Tears / Q000737:chemistry*; D055815:Young Adult
chemical_list: D005136:Eye Proteins; D007071:Immunoglobulin A, Secretory; C005062:acetylcellulose; D002482:Cellulose; D009113:Muramidase; D007781:Lactoferrin