title: Investigation of corneal effect of different types of artificial tears in a simulated dry eye condition using a novel porcine dry eye model (pDEM).
abstract: OBJECTIVE
  To use a novel porcine dry eye model (pDEM) to study the effect of various artificial tears on corneal abrasion and epithelial cell death under severe "dry eye" conditions.
  
  
  METHODS
  A 60-second lacrimation-blink interval, which simulates a severe dry eye condition, was set up with our novel pDEM. The corneal protective effect of lubricating the eye for 4 hours with Dulbecco phosphate-buffered saline (DPBS, as control; n = 20) and with 3 types of commercially available artificial tears (n = 17 for each) that contained different lubricating agents was studied. Effect was determined in terms of the change in fluorescein staining grade (on a 0-4 point scale with 0.5 increments) of the cornea and the number of dead cells (by trypan blue staining) on the corneal surface.
  
  
  RESULTS
  Median increase in fluorescein grading (median) in corneas treated for 4 hours with artificial tears containing sodium hyaluronate or hydroxypropyl methylcellulose was significantly (P < 0.002) smaller than with artificial tears containing balanced saline with an unknown demulcent or the DPBS control. The numbers of dead epithelial cells in the central corneas lubricated with artificial tears containing sodium hyaluronate or hydroxypropyl methylcellulose (229 +/- 71 and 221 +/- 65 [SD], respectively) were also significantly (P < 0.005) smaller than those in the corneas of eyes lubricated with artificial tears containing balanced saline with an unknown demulcent or DPBS alone (328 +/- 106 and 341 +/- 113, respectively).
  
  
  CONCLUSIONS
  Results show that artificial tears containing sodium hyaluronate or hydroxypropyl methylcellulose as lubricating agents give enhanced corneal protection against desiccation and show the use of this novel pDEM model in evaluating corneal protection from desiccation.
authors.affiliation: School of Optometry, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China.
authors.forename: Emily Pik Yin
authors.initials: EP
authors.lastname: Choy
authors.forename: Pauline
authors.initials: P
authors.lastname: Cho
authors.forename: Iris Frances Forster
authors.initials: IF
authors.lastname: Benzie
authors.forename: Camus Kar Man
authors.initials: CK
authors.lastname: Choy
mesh_terms: D000818:Animals; D002470:Cell Survival; D003315:Cornea / Q000187:drug effects* / Q000378:metabolism; D004195:Disease Models, Animal; D015352:Dry Eye Syndromes / Q000378:metabolism / Q000517:prevention & control*; D004847:Epithelial Cells / Q000187:drug effects; D005452:Fluoresceins / Q000378:metabolism; D006820:Hyaluronic Acid / Q000008:administration & dosage; D065347:Hypromellose Derivatives; D008747:Methylcellulose / Q000008:administration & dosage / Q000031:analogs & derivatives; D009883:Ophthalmic Solutions / Q000008:administration & dosage*; D013552:Swine; D014343:Trypan Blue / Q000378:metabolism
chemical_list: D005452:Fluoresceins; D009883:Ophthalmic Solutions; D065347:Hypromellose Derivatives; D006820:Hyaluronic Acid; D008747:Methylcellulose; D014343:Trypan Blue