title: Compliance with contact lens replacement in Canada and the United States.
abstract: OBJECTIVE
  To assess eye care practitioners (ECPs) recommendations for replacement frequency (RF) of silicone hydrogel (SH) and daily disposable (DD) lenses in Canada and the U.S. and to compare noncompliance (NC) with manufacturer recommended RF by the ECP and patient, and the reasons given for NC.
  
  
  METHODS
  Invitations to participate were sent by e-mail to ECPs in Canada and the U.S. Twenty patient surveys were sent to 420 ECPs, and 2232 eligible surveys were received from 216 ECPs (26% Canada, 74% U.S.). Questions related to patient demographics, lens type, wearing patterns, ECP instructions for RF, and actual patient RF. ECPs provided lens information and their recommendation for RF after the surveys were completed and sealed in envelopes. Responses were anonymous.
  
  
  RESULTS
  DD accounted for 18% (Canada) vs. 16% (U.S.) of wearers (p > 0.05); 35% (Canada) vs. 45% (U.S.) wore 2-week replacement SH (2WR; p = 0.011); and 47% (Canada) vs. 39% (U.S.) wore 1-month replacement SH (1MR) lenses (p = 0.025). Thirty-four percent (Canada) vs. 18% (U.S.) of ECPs recommended longer RFs than the manufacturer recommended RF for 2WR lens wearers (p < 0.001); 6% (Canada) vs. 4% (U.S.) for DD wearers; and 2% (Canada) vs. 1% (U.S.) for 1MR lens wearers. NC rates for actual RFs reported by patients were not different between countries (p > 0.05) and were lowest for DD (13% Canada, 12% U.S.), followed by 1MR (33% Canada, 28% U.S.). The highest NC rates were with 2WR (50% Canada, 52% U.S.). The most frequent reason for NC with 2WR and 1MR was "forgetting which day to replace lenses" (54% Canada, 53% U.S.) and in DD wearers "to save money" (56% Canada, 29% U.S., p < 0.001).
  
  
  CONCLUSIONS
  1MR lenses are more frequently prescribed in Canada. ECPs in Canada were NC with 2WR lenses more frequently than U.S. ECPs, but patient NC rates were the same in both countries for all lens types. ECP and patient NC rates were highest for 2WR lens wearers.
authors.affiliation: Centre for Contact Lens Research, University of Waterloo, Waterloo, Ontario, Canada. kdumble@uwaterloo.ca
authors.forename: Kathryn
authors.initials: K
authors.lastname: Dumbleton
authors.forename: Doris
authors.initials: D
authors.lastname: Richter
authors.forename: Craig
authors.initials: C
authors.lastname: Woods
authors.forename: Lyndon
authors.initials: L
authors.lastname: Jones
authors.forename: Desmond
authors.initials: D
authors.lastname: Fonn
mesh_terms: D000328:Adult; D002170:Canada; D003263:Contact Lenses, Hydrophilic / Q000706:statistics & numerical data; D004209:Disposable Equipment / Q000706:statistics & numerical data; D005260:Female; D019983:Guideline Adherence; D006282:Health Personnel; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D008297:Male; D008875:Middle Aged; D009907:Optometry; D010349:Patient Compliance; D012828:Silicones; D011795:Surveys and Questionnaires; D014481:United States
chemical_list: D012828:Silicones; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate