title: What have pre- and postapproval studies shown about contact lens-related inflammatory events?
abstract: BACKGROUND
  Clinical studies that occur before and after the regulatory approval of contact lenses differ in many aspects, including breadth, length, and subject inclusion and exclusion criteria.
  
  
  METHODS
  A sample of published studies conducted in North America was reviewed to outline these differences and show their impact on rates of corneal complications with lenses.
  
  
  RESULTS
  In postapproval studies of silicone hydrogel lenses, subject age and refractive error have been more diverse than in pre-approval trials, for example, 42% of lens wearers in a postapproval study of a single vision contact lens being older than 40 years. Inclusion of subjects in a wider age range in that study showed that lens wearers older than 50 years were at an increased risk for corneal infiltrates. Few adolescents were included in the first pre-approval trials of tisilfocon A overnight orthokeratology lenses, although many teenagers are prescribed the lenses in practice and may be at a higher risk for corneal infections with the device. The range of spectacle refractive error in a large postapproval registry of lotrafilcon A patients ranged from -16.00 to +7.00 diopters, significantly greater than that in pre-approval studies. A nonrandomized postapproval study showed that patient selection resulted in older patients with a higher degree of ametropia receiving silicone hydrogel lenses compared to younger patients with lower ametropia being fitted with hydrogel lenses.
  
  
  CONCLUSIONS
  Postapproval studies give an organized view of the type of patients who will eventually make up the wearing population and their success or limitations with new types of contact lenses.
authors.affiliation: School of Optometry, Indiana University, Bloomington, IN, USA. robinchalmers@mindspring.com
authors.forename: Robin L
authors.initials: RL
authors.lastname: Chalmers
mesh_terms: D000367:Age Factors; D002986:Clinical Trials as Topic; D003261:Contact Lenses / Q000009:adverse effects*; D003263:Contact Lenses, Hydrophilic / Q000009:adverse effects; D003316:Corneal Diseases / Q000209:etiology*; D018795:Device Approval; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D007249:Inflammation / Q000209:etiology*; D054158:Orthokeratologic Procedures / Q000009:adverse effects; D018579:Patient Selection; D012030:Refractive Errors / Q000534:rehabilitation; D012042:Registries; D012307:Risk Factors; D012828:Silicones
chemical_list: D012828:Silicones; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate