The results showed a lower overall adverse event rate for patients who replaced their lenses each morning: about four percent, compared to nearly nine percent with one month of continuous wear. Morning lens replacement was specifically associated with a lower rate of mechanical adverse events, such as scratches and abrasions of the cornea: less than one percent, compared to a little over five percent with monthly replacement.
In contrast, the adverse event rate for patients who replaced their lenses nightly was about eight percentnot significantly different from the rate for monthly lens replacement. Inflammatory adverse events (such as redness and irritation of the eye) were somewhat less common with morning lens replacement, although the difference was not significant.
Lens Handling Linked to Contamination
Microbiology studies in a subgroup of patients found that lenses were frequently colonized with Staph bacteria after handling. In the one-month study, there were no major complications, including the rare but serious infection microbial keratitis.
Extended wear/continuous wear contact lenses are a convenient alternative to daily-wear lenses, avoiding the need for daily lens removal, cleaning, and replacement. Although EW/CW lenses are generally safe, the risk of complications is higher than with daily-wear lenses. Extended wear may provide more time for bacteria to colonize the lens and cause infections.
"The benefit of a fresh lens at night might be partially negated by contamination of the contact lens due to lens handling prior to overnight eye closure," comments Anthony Adams, OD, PhD, Editor-in-Chief of Optometry and Vision Science. "At night, with closed eyes, there is less oxygen getting to the cornea and reduced 'lid wiper' cleaning effect on the lenses."
The new study suggests that replacing lenses in the morning reduces complications related to EW/CW lens w
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