title: The impact of topical corticosteroid use before diagnosis on the outcome of Acanthamoeba keratitis.
abstract: OBJECTIVE
  To examine the impact of topical corticosteroid use before the diagnosis of Acanthamoeba keratitis (AK) on final visual outcomes and to determine the prognostic factors predicting poorer outcomes.
  
  
  METHODS
  Cohort study.
  
  
  METHODS
  A total of 209 eyes of 196 patients with retrievable medical records, diagnosed with AK at Moorfields Eye Hospital, London, between January 1991 and April 2012. One eye was randomly excluded from analysis in the 13 cases of bilateral AK.
  
  
  METHODS
  Patient demographic, initial clinical examination findings, and management details were collected. The outcomes of patients treated with topical corticosteroids before diagnosis of AK were compared with those not treated with topical corticosteroids before diagnosis. A multivariable logistic model, optimized for prior corticosteroid use, was used to derive the odds ratios (ORs) of a suboptimal visual outcome.
  
  
  METHODS
  Suboptimal visual outcome was defined as final visual acuity (VA) ≤ 20/80, corneal perforation, or need for keratoplasty.
  
  
  RESULTS
  Acanthamoeba keratitis was diagnosed on microbiological culture in 94 eyes (48.0%), on histopathologic examination in 27 eyes (13.8%), on confocal microscopy in 38 eyes (19.4%), and on the basis of a typical clinical course and response to treatment in 37 eyes (18.9%). Final VA and prior corticosteroid use data were available for 174 eyes (88.8%). In multivariable analysis, corticosteroid use before diagnosis was associated with suboptimal visual outcome (OR, 3.90; 95% confidence interval [CI], 1.78-8.55), as were disease stage 3 at presentation (OR, 5.62; 95% CI, 1.59-19.80) and older age (60+ years) at diagnosis (OR, 8.97; 95% CI, 2.13-37.79).
  
  
  CONCLUSIONS
  Corticosteroid use before diagnosis of AK is highly predictive of a poorer visual outcome. This is largely due to the initial misdiagnosis of AK as herpetic keratitis. It is important to include AK in the differential diagnosis of keratitis in all contact lens users with keratitis, particularly before making a diagnosis of herpes keratitis and before the use of topical corticosteroids in the therapy of any indolent keratitis.
authors.affiliation: Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom.
authors.forename: Dana
authors.initials: D
authors.lastname: Robaei
authors.affiliation: Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom.
authors.forename: Nicole
authors.initials: N
authors.lastname: Carnt
authors.affiliation: EpiVision Ophthalmic Epidemiology Consultants, Bucks, United Kingdom.
authors.forename: Darwin C
authors.initials: DC
authors.lastname: Minassian
authors.affiliation: National Institute of Health Research Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, United Kingdom. Electronic address: j.dart@ucl.ac.uk.
authors.forename: John K G
authors.initials: JK
authors.lastname: Dart
mesh_terms: D015823:Acanthamoeba Keratitis / Q000175:diagnosis* / Q000188:drug therapy*; D000287:Administration, Topical; D000293:Adolescent; D000328:Adult; D000981:Antiprotozoal Agents / Q000627:therapeutic use; D001645:Biguanides / Q000627:therapeutic use; D002710:Chlorhexidine / Q000627:therapeutic use; D015331:Cohort Studies; D004359:Drug Therapy, Combination; D005260:Female; D005938:Glucocorticoids / Q000008:administration & dosage / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D010419:Pentamidine / Q000627:therapeutic use; D016896:Treatment Outcome; D014792:Visual Acuity / Q000187:drug effects; D055815:Young Adult
chemical_list: D000981:Antiprotozoal Agents; D001645:Biguanides; D005938:Glucocorticoids; C031233:polihexanide; D010419:Pentamidine; D002710:Chlorhexidine