title: Benzalkonium chloride induces anterior chamber inflammation in previously untreated patients with ocular hypertension as measured by flare meter: a randomized clinical trial.
abstract: OBJECTIVE
  The deleterious effects of benzalkonium chloride (BAK) on the ocular surface are well known. However, few clinical data are available to prove a toxic effect at the level of the anterior chamber. The laser flare meter is a reliable tool to detect low levels of inflammation in the anterior chamber. We wanted to know whether instillation of BAK-preserved timolol in one eye would result in higher laser flare values than the instillation of preservative-free timolol in the fellow eye.
  
  
  METHODS
  Randomized prospective, single-masked clinical trial. Twenty-eight untreated patients with ocular hypertension were recruited. After obtaining baseline flare values, we randomly assigned one eye to BAK-preserved timolol and the fellow eye to preservative-free timolol. After 1 month, flare measurements were repeated.
  
  
  RESULTS
  There was a significant increase in the flare values in the two treatment regimens, but the increase in the BAK-treated eyes was higher than in the preservative-free treated eyes, and this difference in increase was statistically significant.
  
  
  CONCLUSIONS
  This is the first study to show that short-term BAK administration produces inflammation in the anterior segment of previously untreated patients whose blood-aqueous barrier was not affected by recent intraocular surgery.
authors.affiliation: Department of Ophthalmology, Ghent University Hospital, Ghent, Belgium.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Stevens
authors.forename: Philippe A
authors.initials: PA
authors.lastname: Kestelyn
authors.forename: Dirk
authors.initials: D
authors.lastname: De Bacquer
authors.forename: Philippe G
authors.initials: PG
authors.lastname: Kestelyn
mesh_terms: D000328:Adult; D000368:Aged; D000959:Antihypertensive Agents / Q000008:administration & dosage; D001082:Aqueous Humor / Q000378:metabolism*; D001548:Benzalkonium Compounds / Q000009:adverse effects*; D018916:Blood-Aqueous Barrier / Q000187:drug effects*; D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation; D005260:Female; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D009798:Ocular Hypertension / Q000188:drug therapy*; D011310:Preservatives, Pharmaceutical / Q000009:adverse effects*; D011446:Prospective Studies; D016037:Single-Blind Method; D013999:Timolol / Q000008:administration & dosage; D014606:Uveitis, Anterior / Q000139:chemically induced* / Q000175:diagnosis / Q000378:metabolism
chemical_list: D000959:Antihypertensive Agents; D001548:Benzalkonium Compounds; D011310:Preservatives, Pharmaceutical; D013999:Timolol