title: Asymptomatic corneal staining associated with the use of balafilcon silicone-hydrogel contact lenses disinfected with a polyaminopropyl biguanide-preserved care regimen.
abstract: OBJECTIVE
  To compare subjective symptoms and signs in a group of individuals who wear silicone-hydrogel lenses on a daily wear basis while they sequentially used two differing care regimens.
  
  
  METHODS
  Fifty adapted soft-lens wearers were fitted with a silicone-hydrogel lens material (PureVision, Bausch & Lomb). The lenses were worn on a daily wear basis for two consecutive 1-month periods, during which the subjects used either a Polyquad (polyquaternium-1) -based system or a polyaminopropyl biguanide (PHMB) -based system, using a double-masked, randomized, crossover experimental design.
  
  
  RESULTS
  Significant levels of relatively asymptomatic corneal staining were observed when subjects used the PHMB-based system, with 37% of subjects demonstrating a level of staining consistent with a classical solution-based toxicity reaction. Only 2% of the subjects exhibited such staining when using the Polyquad-based system. These results were significantly different (p < 0.001). Significant symptoms were not correlated with the degree of staining, with no differences in lens comfort or overall preference being reported between the regimens (p = NS). The only statistically significant difference in symptoms related to minor differences in stinging after lens insertion being reported, with the Polyquad-based system demonstrating less stinging (p < 0.008).
  
  
  CONCLUSIONS
  Practitioners who fit silicone-hydrogel contact lenses on a daily wear basis should be wary of the potential for certain PHMB-containing multipurpose care systems to invoke corneal staining. Switching to non-PHMB based regimens will eliminate this complication in most instances.
authors.affiliation: Centre for Contact Lens Research, School of Optometry, University of Waterloo, Waterloo, Ontario, Canada. lwjones@uwaterloo.ca
authors.forename: Lyndon
authors.initials: L
authors.lastname: Jones
authors.forename: Nancy
authors.initials: N
authors.lastname: MacDougall
authors.forename: L Gina
authors.initials: LG
authors.lastname: Sorbara
mesh_terms: D000328:Adult; D001645:Biguanides / Q000009:adverse effects*; D003228:Conjunctiva / Q000098:blood supply / Q000473:pathology; D018639:Contact Lens Solutions / Q000009:adverse effects*; D003262:Contact Lenses, Extended-Wear; D003315:Cornea / Q000473:pathology*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D006940:Hyperemia / Q000139:chemically induced; D008297:Male; D011108:Polymers / Q000009:adverse effects; D012828:Silicones; D013194:Staining and Labeling
chemical_list: D001645:Biguanides; D018639:Contact Lens Solutions; D011108:Polymers; D012828:Silicones; C064420:polyaminopropylbiguanide; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; C058655:polyquaternium 1