WHY PRESERVATIVE FREE
Several television ad campaigns encourage patients to inform their doctors and pharmacists about all the medications they are taking in order to avoid harmful drug interactions. This is good advice for patients on artificial tears as well.

An ocular medication is much more than just the active drug it contains. Its other components may present difficulties for some patients. This is true for patients who are using artificial tear products, suffer chronic eye diseases like dry eye or glaucoma, or require post-surgery dosing of medication drops.

Eye drops are composed of unique mixtures of:
the active drug and its drug delivery system
a preservative
a viscosity increasing agent
a vehicle by which all the above ingredients are "carried"

Of these, it’s the preservative that is most often considered to be the culprit in damaging the top layer of .the cornea leading to disruption when drops are used often. This sequence leaves the surface of the eye unable to keep the tear film in place and can lead to ocular surface disease. If you are using certain medication drops or wear contact lenses it is even more important to have tears that are preservative free.

Common chemical preservatives found in ophthalmic drops are:
Benzalkonium chloride (BAK)
Disodium EDTA

BAK is the most prevalent and its cytotoxicity is well-documented. Reports have shown that BAK can accumulate in ocular tissue and can cause different types of cell death with frequent dosing. It’s thought that patients at greatest risk for BAK-induced adverse effects are those suffering from dry eyes. Because of the lack of natural tears in these patients, the BAK in each eye drop is not as diluted as it would be in a patient with normal tear formation. This may damage the corneal epithelium (top layer of the eye) contributing to ocular surface disease. (Using more than 4 – 6 drops per day increases the likelihood of BAK-induced adverse effects.)

Non-preserved Drops
Studies have shown preservative-free preparations are safe to use in patients, with frequent dosing.

Non-preserved artificial tears have an extra advantage over preserved ones. They may be the best choice for patients immediately following eye surgery (LASIK) due to increased viscosity and pH buffering, which makes the drops more comfortable to use. Preservative-free Oasis TEARS™ and Oasis TEARS™ PLUS eliminate the source of toxic irritation caused by preservatives.