title: The incidence of microbial keratitis among wearers of a 30-day silicone hydrogel extended-wear contact lens.
abstract: OBJECTIVE
  To estimate the incidence of presumed microbial keratitis with and without loss of visual acuity among wearers of a silicone hydrogel contact lens (Lotrafilcon A, Night & Day, CIBA Vision, Inc., Duluth, GA), recently approved for up to 30 days of continuous wear.
  
  
  METHODS
  Prospective cohort postmarket surveillance study.
  
  
  METHODS
  Contact lens wearers (recruited from 131 practices) who had been prescribed the lens for intended continuous wear of as many as 30 nights.
  
  
  METHODS
  The occurrence of a corneal infiltrate was ascertained through a combination of center report and direct contact with participants at 3 and 12 months. Whenever a corneal infiltrate was suspected, study and treatment medical records were systematically reviewed by an Endpoints Committee using a predetermined classification scheme for corneal infiltration. Cases of presumed microbial keratitis were determined based on the constellation of presenting signs and symptoms and clinical course.
  
  
  METHODS
  The incidence of presumed microbial keratitis with and without loss of visual acuity.
  
  
  RESULTS
  A total of 6245 participants were recruited between August 13, 2002 and July 2, 2003. Of these, 4999 subjects (80%) completed 12 months of follow-up, and these participants contributed a total of 5561 person years of lens wearing experience. Approximately 80% of participants routinely wore their lenses continuously for 3 or more weeks. The overall annual rate of presumed microbial keratitis was 18 per 10,000 (95% confidence interval (CI): 8.5-33.1). There were 2 cases of presumed microbial keratitis with loss of visual acuity, an annual rate of 3.6 per 10,000 (95% CI: 0.4-12.9), and an additional 8 cases without loss of visual acuity, an annual rate of 14.4 per 10000 (95% CI: 6.1-28.4). The rate of presumed microbial keratitis was lower for users reporting typical wear of 3 or more weeks than for those wearing the lens for less than a 3-week continuous period (P = 0.02).
  
  
  CONCLUSIONS
  The incidence of loss of visual acuity due to microbial keratitis among users of the silicone hydrogel contact lens was low. The overall rate of presumed microbial keratitis with the wearing schedule of as many as 30 nights was similar to that previously reported for conventional extended-wear soft lenses worn for fewer consecutive nights.
authors.affiliation: Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA. oschein@jhmi.edu
authors.forename: Oliver D
authors.initials: OD
authors.lastname: Schein
authors.forename: John J
authors.initials: JJ
authors.lastname: McNally
authors.forename: Joanne
authors.initials: J
authors.lastname: Katz
authors.forename: Robin L
authors.initials: RL
authors.lastname: Chalmers
authors.forename: James M
authors.initials: JM
authors.lastname: Tielsch
authors.forename: Eduardo
authors.initials: E
authors.lastname: Alfonso
authors.forename: Mark
authors.initials: M
authors.lastname: Bullimore
authors.forename: Denis
authors.initials: D
authors.lastname: O'Day
authors.forename: Joseph
authors.initials: J
authors.lastname: Shovlin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001672:Biocompatible Materials; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003262:Contact Lenses, Extended-Wear / Q000706:statistics & numerical data*; D003320:Corneal Ulcer / Q000453:epidemiology* / Q000382:microbiology*; D018795:Device Approval; D005260:Female; D006801:Humans; D020100:Hydrogels; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011358:Product Surveillance, Postmarketing / Q000706:statistics & numerical data; D011446:Prospective Studies; D012828:Silicones; D014481:United States; D014486:United States Food and Drug Administration; D014792:Visual Acuity; D005466:Fluorocarbons
chemical_list: D001672:Biocompatible Materials; D020100:Hydrogels; D012828:Silicones; C481129:lotrafilcon A; D005466:Fluorocarbons