title: Risk factors for corneal inflammatory and mechanical events with extended wear silicone hydrogel contact lenses.
abstract: OBJECTIVE
  To identify risk factors for contact lens-related corneal inflammatory events and mechanical events in wearers of silicone hydrogel lenses on a 30-night extended wear (EW) schedule in India.
  
  
  METHODS
  An interventional study with 188 subjects wearing silicone hydrogel lenses bilaterally on a 30-night EW schedule. Subjects were dispensed with lenses and reviewed at scheduled visits up to 6 months of EW. Multivariate logistic regression, after adjusting for within subject correlation, was used to develop the statistical model.
  
  
  RESULTS
  Occupations in non-ideal environments were found to predispose a lens wearer to inflammatory events (p = 0.003). Wearers in the non-ideal group, who had varying degrees of exposure to ocular irritants in their work environment had highest incidence of inflammatory events (19.2%). Wearers in a controlled, ideal environment had lowest levels of events (3.3%). Students occupied a position between the two groups (9.3%). Inflammatory rate was higher among wearers with increased microbial contamination of lenses (p = 0.002). Wearers with an inflammatory event had mean colony forming unit of 1.97 log compared with mean colony forming unit of 1.45 log in group with no inflammatory event. Corneal vascularization was associated with the development of inflammatory events (p = 0.001) with 50% of wearers with vascularization experiencing events compared with 7.6% of subjects with no vascularization. Reduced lens movement was associated with inflammatory events with subjects more likely to develop inflammatory events compared with those wearers with optimal lens movement (p = 0.027).
  
  
  CONCLUSIONS
  A multitude of factors, including environmental influences, lens contamination, ocular characteristics, and lens fit, contributes to the development of inflammatory events, information that is of clinical relevance to practitioners worldwide. Occupational environment was also a contributory factor, confirming that a duty of clinicians is to ascertain the nature of the work environment of lens wearers (and potential wearers) and to balance the needs of the wearer with the potential risks.
authors.affiliation: Brien Holden Vision Institute, New South Wales, Queensland, Australia. j.ozkan@brienholdenvision.org
authors.forename: Jerome
authors.initials: J
authors.lastname: Ozkan
authors.forename: Preeji
authors.initials: P
authors.lastname: Mandathara
authors.forename: Pravin
authors.initials: P
authors.lastname: Krishna
authors.forename: Padmaja
authors.initials: P
authors.lastname: Sankaridurg
authors.forename: Thomas
authors.initials: T
authors.lastname: Naduvilath
authors.forename: Mark D P
authors.initials: MD
authors.lastname: Willcox
authors.forename: Brien
authors.initials: B
authors.lastname: Holden
mesh_terms: D000293:Adolescent; D000328:Adult; D003262:Contact Lenses, Extended-Wear / Q000009:adverse effects* / Q000382:microbiology; D016510:Corneal Neovascularization / Q000209:etiology; D004866:Equipment Contamination; D005260:Female; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D015994:Incidence; D007509:Irritants / Q000009:adverse effects; D007634:Keratitis / Q000453:epidemiology / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D009038:Motion; D009784:Occupational Diseases / Q000453:epidemiology / Q000209:etiology; D017755:Prosthesis Fitting / Q000009:adverse effects*; D012307:Risk Factors; D012828:Silicones; D055815:Young Adult
chemical_list: D007509:Irritants; D012828:Silicones; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate