the contact lens case

As eye care professionals, we talk a lot about the proper care of contact lenses, but we probably don't spend enough time talking about the proper care of the contact lens CASE. Sure, it doesn't actually go ON your eyeball, but it does matter! The contact lens case can act as a reservoir for microorganisms and can be the source of eye infections, with the contact lens serving as the vector.  Some microbes can attach to the case and secrete substances that create an extracellular matrix-type protective encasement called a biofilm. This allows adherence to biological tissue, plastics, medical devices, etc. The ideal environment for biofilms to attach and grow is a moist surface, which makes contact lens cases prime real estate (1). 

So how should you be taking care of your contact lens case?

1. Change the case AT LEAST every 3 months.  Look at the photos below. Crystal violet stains protein and DNA, the primary components of cellular debris.  You can see that the intensity of the staining correlates with the age of the lens case (2). The longer you use the case, the more bacteria and debris collects, which increases your risk of infection.

image: RCCL

2. Clean the case daily by rubbing and rinsing with fresh contact lens solution (not water). A study found that 52% of those questioned cleaned their cases with tap water (3).  Why is that bad?  Because tap water contains microorganisms that can lead to rare but serious eye infections, like Acanthamoeba keratitis. In another study, cleaning cases with tap water was found to be associated with a higher rate of contamination with gram negative bacteria (4). Multipurpose solutions are designed to interfere with the cell membrane of microorganisms and kill them. Hydrogen peroxide-based solutions use a different method to disrupt the microbial membrane, as well as the DNA and other cellular components (5).  

3. Wipe the contact lens case with a clean tissue, and place the case upside down to air dry in a clean area (ie: not inches from the toilet). Simply rinsing with contact lens solution is not enough to destroy biofilms; mechanical disruption is needed (3, 7).  More bacterial contamination was found to occur in humid environments, most notably when the case was left to air dry face up (8).  So the research tells us that the most effective way to clean your contact lens case is to rub and rinse the contact lens case with fresh contact lens solution daily, wipe the case with a clean tissue, and leave it face down on a clean surface to air dry (9, 10).  

The proper way to store your case: upside down on a clean tissue.

4. Be sure to keep the contact lenses themselves clean!  More on that in a previous post.

Even better yet? Get rid of the case all together and opt for daily disposable contact lenses. You put them in in the morning, remove and discard them in the evening, and start with a fresh pair the next day. Talk to your optometrist to see if those are an option for you.

CliffsNotes: Rub and rinse the contact lens case with fresh contact lens solution (not water) daily, dry with a clean tissue, and leave upside down on a clean tissue to air dry. RUB, RINSE, TISSUE-DRY, AIR-DRY. Replace the case at least every 3 months. 

Additional Resources:

• CDC: Contact Lens Care
• AOA: Caring for Contact Lenses