Extended Wear of Contact Lenses
Background
Extended wear and continuous wear are synonymous terms that describe a modality of overnight contact lens wear, usually for a period of one to four weeks. Soft hydrogel lenses, including the latest highly gas-permeable silicone hydrogel lenses, and rigid gas permeable lenses have been used for extended wear. Extended wear lenses have proven popular because of their convenience. However, concerns regarding the relative safety of soft hydrogel lenses for extended wear prompted several studies to examine the rate of adverse reactions among users of such contract lenses.
In a series of studies1-7 the risk of developing ulcerative keratitis with soft hydrogel lenses was:
a) Ten to 15 times greater in extended wear versus daily wear users;
b) Nine times greater in elderly patients using extended wear lenses for correction of aphakia;
c) Twelve times greater in individuals misusing daily wear lenses for overnight wear;
d) Proportionally greater with increased consecutive days of extended wear lens wear before removal;
e) Less with more frequent lens removal, lens care, and especially with frequent contact lens case cleaning.
Overnight wear, regardless of contact lens type, increases the likelihood of corneal infection.3,5,6,8-11A small percentage of patients that were fitted with gas-permeable soft silicone hydrogel contact lenses developed sterile inflammatory peripheral corneal infiltrates within one year of use.12 A study of patients using silicone hydrogel contact lenses continuously for up to 30 days concluded that the overall rate of microbial keratitis was similar to that of conventional soft extended wear lenses.8These lenses are FDA approved for 30 days of extended wear.