To answer this question it is important to establish that there are two different kinds of “daily” contacts. There are daily disposable contact lenses, and then there are daily extended use contact lenses. There are major differences in the way that these lenses are designed and how long they can safely be used for.
How long can I wear my daily disposable contact lenses?
Daily disposable contact lenses are to be worn for one day only. They are a single use lens that is not designed to be resistant to germs, bacteria, and other buildup that collects on the lens throughout the day. These lenses are commonly sold in large quantity boxes of 30-180 lenses per box. Daily disposable contacts are much thinner and therefore usually more comfortable and breathable. Many users attempt to “stretch” the life span of these lenses by cleaning them in a disinfecting solution and wearing them for multiple days, or worse, weeks at a time. The material of the lens is not made of a matrix that allows for cleaning away germs and other micro-organisms. The process of cleaning these lenses is generally ineffective and actually breaks down the lens itself increasing the risk of the lens falling apart while it is on the eye. A daily disposable lens is very much like a paper plate. It is very thin, but after a plate of food is served on one, the food particles are deeply absorbed into the material instead of just being on the surface. Running it through a dishwasher doesn’t really achieve the desired effect of reusing it. The risk of complications and infection of not worth the few dollars that one may save. Daily disposable contacts are designed to be thrown away after every single use.
How long can daily wear contact lenses be worn?
Daily wear contact lenses can be safely disinfected for reuse for 2 weeks to a month before discarding. Daily wear contact lenses are made to be worn during the day only, but can safely be reused for up to a month. It is important to check with your doctor and the manufacturer of the daily wear contacts to find out the recommended wear time, as not all contacts can be reused for up to a month. These contacts are not meant to be slept in overnight. Upon removal of the lenses, they are to be cleaned and disinfected with the cleaning system recommended by your optometrist. These lenses are made of complex materials that are bonded with protective layers of synthetic materials that are resistant to the normal buildup of bacteria, protein, germs, and debris that occurs with wearing contact lenses. The material of these lenses is also designed to be cleaned, disinfected without a major breakdown in the material composition of the lens itself. These lenses are like a porcelain plate, it can be cleaned, rinsed and disinfected with the desired results of reuse.
The reality of contamination with reusing daily disposable contact lenses.
Many studies show that well over half of contact lens wearers are not compliant with the prescribed wearing and cleaning schedule of their daily contact lenses. We aren’t pointing the finger at anyone in particular, but you know who you are. So lets talk about Staphylococci. This is an extremely common bacteria that can take on many different pathogenic varieties. Infections caused from it can cause pus formation, especially in the skin and mucous membranes. This is important to those considering (or actively) reusing their daily disposable lenses. The eye is wet and exposed to vulnerable tissue. It is filled with mucous membranes and warm crevices and pockets for bacteria to form. A study conducted by the Department of Health Technology at The Hong Kong Polytechnic University concluded that there was a contamination rate of over 45% of daily disposable lenses having Staphylococci present after a single day of reusing them1. The study was only looking for this singular type of bacteria. One can only imagine the variety of other germs and organisms that are also contaminating these lenses after reuse. For those that are reusing daily disposable lenses, it is a dangerous action to take, with painful and risky outcomes when an infection finally does happen.
1Contamination Risk of Reusing Daily Disposable Contact Lenses, Boost, Maureen; Poon, Kin-Chiu; Cho, Pauline; Optometry and Vision Science: December 2011 – Volume 88 – Issue 12 – p 1409-1413