title: The effect of compliance on contact lens case contamination.
abstract: OBJECTIVE
  To determine the efficacy of written instructions on contact lens case hygiene and to quantify the effect of noncompliance on contact lens case contamination.
  
  
  METHODS
  Data were retrospectively analyzed from 16 prospective, 3-month daily-wear studies during which six commercially available silicone hydrogel contact lenses and seven lens care solutions (LCS) were tested following a similar protocol. Verbal instructions regarding case hygiene (rinse case with LCS, not tap water) were given in nine studies, while the same instructions were given verbally and in written format in seven studies. A survey on contact lens, LCS, and lens case hygiene was completed at 1- and 3-month visits and compliance with case hygiene instructions was determined. Regular contact lens cases were used for 1 month and collected for microbial analysis at the 1- and 3-month visits. The rate of case contamination and the types of microbes contaminating cases were evaluated.
  
  
  RESULTS
  Participants given verbal and written instructions were more likely to be compliant with case hygiene instructions than those just given verbal instructions (odds ratio [OR]: 2.19, p < 0.001, 95% confidence interval [CI]: 1.40-3.44). The overall case contamination rate was 79%. Use of tap water to rinse contact lens cases was associated with significantly more cases contaminated with Gram-negative bacteria (GNB) (30% vs. 10%, p < 0.001), a greater risk of GNB case contamination (OR: 2.91, p < 0.001. 95% CI: 1.72-4.92), and a higher quantity of GNB in cases (mean colony-forming unit/case ± SD: 28,286 ± 131,935 vs. 6477 ± 60,447, p < 0.001).
  
  
  CONCLUSIONS
  Lens case hygiene can be improved by effective communication of instructions. Contact lens wearers should be actively discouraged from rinsing contact lens cases with tap water because of the increased risk of GNB contamination.
authors.affiliation: *BOptom(Hons), MOptom †PhD, FAAO ‡PhD Brien Holden Vision Institute (DT, PLdlJ, HZ, TJN, BAH), Sydney, New South Wales, Australia; School of Optometry and Vision Science (PLdlJ, BAH), University of New South Wales, Sydney, New South Wales, Australia; and Vision Cooperative Research Centre (BAH), Sydney, New South Wales, Australia.
authors.forename: Daniel
authors.initials: D
authors.lastname: Tilia
authors.forename: Percy
authors.initials: P
authors.lastname: Lazon de la Jara
authors.forename: Hua
authors.initials: H
authors.lastname: Zhu
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Naduvilath
authors.forename: Brien A
authors.initials: BA
authors.lastname: Holden
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003142:Communication; D018639:Contact Lens Solutions / Q000627:therapeutic use; D003263:Contact Lenses, Hydrophilic; D004203:Disinfection / Q000379:methods*; D004866:Equipment Contamination / Q000517:prevention & control*; D005260:Female; D006090:Gram-Negative Bacteria / Q000302:isolation & purification; D006306:Health Surveys; D006801:Humans; D006920:Hygiene / Q000592:standards*; D008297:Male; D008875:Middle Aged; D010349:Patient Compliance; D010353:Patient Education as Topic; D010817:Physician-Patient Relations; D012189:Retrospective Studies; D012826:Silicone Elastomers; D055815:Young Adult
chemical_list: D018639:Contact Lens Solutions; D012826:Silicone Elastomers