title: The impact of artificial tears containing hydroxypropyl guar on mucous layer.
abstract: OBJECTIVE
  The aim of this study was to investigate the effect of lubricant eyedrops containing propylene glycol 400 (PEG) and polyethylene glycol (PG) with hydroxypropyl guar (HP-guar) as a gelling agent on the precorneal mucous layer in vivo.
  
  
  METHODS
  Sixteen New Zealand white rabbits were randomly assigned to 1 of 4 groups. All rabbits received PEG/PG/HP-guar tear products in the right eye. PEG/PG/HP-guar with Polyquad, 0.1% hyaluronate sodium, 0.5% carboxymethylcellulose, or phosphate-buffered saline was placed in the left eyes of animals in each group. All eyedrops were used 4 times a day for 7 days. An additional 8 rabbits were randomly assigned to 1 of 2 groups. One group received PEG/PG/HP-guar products 4 times a day for 7 days (long-term exposure group), and the other group received PEG/PG/HP-guar products 3 times at 5-minute intervals (short-term exposure group). Fifteen minutes after the last drop was administered, each cornea was immediately excised and mucous layer thickness measured by transmission electron microscopy.
  
  
  RESULTS
  Mucous layer thickness was significantly greater in eyes treated with PEG/PG/HP-guar products compared with those treated with 0.1% hyaluronate sodium, 0.5% carboxymethylcellulose, or phosphate-buffered saline (all P values < 0.001). There were no significant differences in mucous layer thickness between PEG/PG/HP-guar products and PEG/PG/HP-guar with Polyquad or in the long- and short-term exposure animals.
  
  
  CONCLUSIONS
  This study demonstrates that even a short exposure to PEG/PG/HP-guar tear product increased precorneal mucous layer thickness.
authors.affiliation: Deparment of Ophthalmology, East-west Neo Medical Center, Kyung Hee University College of Medicine, Seoul, Republic of Korea.
authors.forename: Sang-Woong
authors.initials: SW
authors.lastname: Moon
authors.forename: Je-Hyung
authors.initials: JH
authors.lastname: Hwang
authors.forename: So-Hyang
authors.initials: SH
authors.lastname: Chung
authors.forename: Kee-Hyun
authors.initials: KH
authors.lastname: Nam
mesh_terms: D000818:Animals; D002266:Carboxymethylcellulose Sodium / Q000633:toxicity; D003315:Cornea / Q000187:drug effects* / Q000648:ultrastructure; D004338:Drug Combinations; D006820:Hyaluronic Acid / Q000633:toxicity; D008297:Male; D046529:Microscopy, Electron, Transmission; D009092:Mucous Membrane / Q000187:drug effects / Q000648:ultrastructure; D009883:Ophthalmic Solutions / Q000633:toxicity*; D011092:Polyethylene Glycols / Q000633:toxicity*; D011134:Polysaccharides / Q000633:toxicity*; D011817:Rabbits
chemical_list: D004338:Drug Combinations; D009883:Ophthalmic Solutions; D011134:Polysaccharides; C519976:hydroxypropyl guar; D011092:Polyethylene Glycols; D006820:Hyaluronic Acid; D002266:Carboxymethylcellulose Sodium