title: Effect of hypotonic 0.4% hyaluronic acid drops in dry eye patients: a cross-over study.
abstract: OBJECTIVE
  The aim of the study is to evaluate the short-term effects of 2 kinds of artificial tears, both containing 0.4% hyaluronic acid in an aqueous solution yet having different osmolarity, on the typical symptoms of patients suffering from dry eye and on the vitality of corneal and conjunctival epithelial cells.
  
  
  METHODS
  A cross-over, randomized, balanced, single-blind study involving 28 patients was divided into 2 treatment groups: group A (unpreserved 0.4% hyaluronic acid eye drops 300 mOsm/L) and group B (unpreserved 0.4% hyaluronic acid eye drops 150 mOsm/L). Both treatments were administered for 7 days, being dosed as a 1 solution drop 4 times daily. After a 1-day wash-out period, the patients in group A passed over to group B and vice versa.
  
  
  RESULTS
  Treatment with hypotonic solution gave better results in relieving symptoms, along with a statistically significant improvement (P < 0.001) in the state of the corneoconjunctival epithelium, than the isotonic solution. At the end of the study, 60.7% of the patients declared that they preferred hypotonic solution and only 10.7% preferred isotonic solution; the remaining 28.6% did not notice any difference between the 2 treatments.
  
  
  CONCLUSIONS
  By reducing the osmolarity of tear film, the hypotonic solution not only improves the characteristics of tear film and the vitality of the epithelial cells of the cornea and conjunctiva but also proves to be effective in reducing dry eye symptoms.
authors.affiliation: Eye Clinic-Fondazione IRCCS Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena, Milano, Italy.
authors.forename: Pasquale
authors.initials: P
authors.lastname: Troiano
authors.forename: Gaspare
authors.initials: G
authors.lastname: Monaco
mesh_terms: D002470:Cell Survival; D003228:Conjunctiva / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology; D018592:Cross-Over Studies; D015352:Dry Eye Syndromes / Q000188:drug therapy* / Q000503:physiopathology; D004847:Epithelial Cells / Q000187:drug effects; D019573:Epithelium, Corneal / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology; D005260:Female; D006801:Humans; D006820:Hyaluronic Acid / Q000008:administration & dosage*; D007038:Hypotonic Solutions / Q000008:administration & dosage*; D007552:Isotonic Solutions / Q000008:administration & dosage; D008297:Male; D008875:Middle Aged; D009883:Ophthalmic Solutions / Q000737:chemistry* / Q000627:therapeutic use*; D009994:Osmolar Concentration; D017060:Patient Satisfaction; D016037:Single-Blind Method; D016896:Treatment Outcome
chemical_list: D007038:Hypotonic Solutions; D007552:Isotonic Solutions; D009883:Ophthalmic Solutions; D006820:Hyaluronic Acid