Wearing Contact Lenses Past Their Prime

June 4, 2009 -- If you wear contact lenses, you might want to check your calendar. A new survey shows that 40% of contact lens wearers don’t replace their lenses in keeping with lens makers' guidelines.

The survey -- conducted in February by researchers at the Centre for Contact Lens Research at Canada's University of Waterloo -- included 1,654 U.S. adults who wear contact lenses.

Patients wore various types of contact lenses: 45% wore silicone hydrogel lenses that should be replaced every two weeks, 39% wore silicone hydrogel lenses that should be replaced monthly, and 16% wore disposable lenses that should be replaced daily.

In the survey, patients reported how often they replaced their contact lenses. Overall, 40% kept their lenses beyond the maker's recommended date. That includes 59% of patients with two-week silicone hydrogel lenses, 29% for one-month silicone hydrogel lenses, and 15% of daily disposable lenses.

Why didn't they replace their lenses on time? For patients with two-week or one-month silicone hydrogel lenses, the top reason was forgetting exactly when they were supposed to get new lenses. They were the most likely patients to say it would be helpful to have a reminder system -- such as an email or text message -- to tell them when to replace their lenses.

But patients with daily disposable lenses had a different reason for keeping their lenses too long. Saving money was their main motivation.

Another reason might be the instructions some patients got from their eye care practitioners; 9% of eye care practitioners who took part in the survey recommended keeping lenses for longer than the manufacturers recommended.

Younger patients were more likely to keep their contact lenses beyond the manufacturer's recommended date.

The survey, which was sponsored by contact lens company CIBA Vision, doesn't show how overdue patients typically were in replacing their contact lenses.