title: [The effects of ocular hypotensive drugs on the cornea: an in vivo analysis with confocal microscopy].
abstract: OBJECTIVE
  To evaluate the effects of anti-glaucoma treatments containing benzalconium chloride (BAC) on the human cornea.
  
  
  METHODS
  A prospective single masked cohort study was conducted on the 50 eyes of 50 patients. The inclusion criteria were: recently diagnosed glaucoma or ocular hypertension with previous treatment, or ophthalmologist-prescribed anti-glaucoma therapy, and oral consent to participate in the study. The patients were not randomised, as the ophthalmologist decided the best therapy according to clinical criteria. The patients were divided in 2 cohorts: one exposed to BAC (23 patients), and not exposed (27 patients). The mean follow-up period was 22 weeks (range 18-30). The change in cell density before and after therapy was measured in: basal layer epithelium, basal layer of limbal epithelium and endothelium. The change in stromal reflectivity and the number of nerve branches in sub-basal nerve plexus was also measured. BAC exposure was blinded to the main researcher.
  
  
  RESULTS
  A greater increase in basal layer epithelium cell density was observed in BAC exposed cohort (P<.05). No significant differences were detected in the endothelium, limbal cell density, stromal reflectivity, or sub-basal nerve plexus. Age, sex, IOP, active ingredient or BAC concentration did not affect the direction or magnitude of the ocular surface alterations found.
  
  
  CONCLUSIONS
  Chronic anti-glaucoma therapy induces changes in the corneal epithelium. Preservative free drops showed less disruption of the ocular surface by confocal microscopy analysis. Further studies should be conducted to evaluate the clinical impact of these histological findings.
authors.affiliation: Servicio de Oftalmología, Hospital Universitario de Fuenlabrada, Madrid, España. Electronic address: hector_fernan@hotmail.com.
authors.forename: H
authors.initials: H
authors.lastname: Fernández Jiménez-Ortiz
authors.forename: N
authors.initials: N
authors.lastname: Toledano Fernández
authors.forename: C S
authors.initials: CS
authors.lastname: Fernández Escamez
authors.forename: S
authors.initials: S
authors.lastname: Perucho Martinez
authors.forename: M J
authors.initials: MJ
authors.lastname: Crespo Carballés
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000959:Antihypertensive Agents / Q000627:therapeutic use; D001548:Benzalkonium Compounds / Q000009:adverse effects*; D003315:Cornea / Q000187:drug effects* / Q000473:pathology; D005260:Female; D005902:Glaucoma, Open-Angle / Q000188:drug therapy; D006801:Humans; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D011310:Preservatives, Pharmaceutical / Q000009:adverse effects*; D011446:Prospective Studies; D016037:Single-Blind Method
chemical_list: D000959:Antihypertensive Agents; D001548:Benzalkonium Compounds; D011310:Preservatives, Pharmaceutical
keywords: Benzalconium chloride; Cloruro de benzalconio; Cohort studies; Confocal microscopy; Cornea; Córnea; Estudios de cohortes; Glaucoma; Microscopia confocal