| Abstract | INTRODUCTION: 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 | Robin L Chalmers
(Affiliation: School of Optometry, Indiana University, Bloomington, IN, USA. robinchalmers at mindspring.com)
|
| Journal | Eye & contact lens
(Eye Contact Lens)
Vol. 33
Issue 6 Pt 2
Pg. 388-91; discussion 399-400
(Nov 2007)
ISSN: 1542-2321 United States |
| PMID | 17975428
(Publication Type: Journal Article, Review)
|
| Chemical References |
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| Topics |
- Age Factors
- Clinical Trials as Topic
- Contact Lenses
(adverse effects)
- Contact Lenses, Hydrophilic
(adverse effects)
- Corneal Diseases
(etiology)
- Device Approval
- Humans
- Hydrogel
- Inflammation
(etiology)
- Orthokeratologic Procedures
(adverse effects)
- Patient Selection
- Refractive Errors
(rehabilitation)
- Registries
- Risk Factors
- Silicones
|
