Dry eye, Contact lenses and Preservatives in Glaucoma Medication

Abstract

Current review focus on hidden links between glaucoma, contact lenses and Ocular Surface Disease (OSD), in glaucoma the most important treatment is the control of progression through targeted pharmaceutical protection, keeping low intraocular pressure, by prescribing ophthalmic medications. On the other hand, use of preservatives in glaucoma medications is a common practice in order to maintain their effectiveness for an extended period of time. Anti-glaucoma medications enclose preservatives and the 70% of them contain a very common preserving agent, the Benzalkonium chloride (BAK). In glaucoma medications BAK toxicity includes, loss of tear film stability, direct damages to the cornea and conjunctival epithelium, and possible immune allergic reactions. Other types of preservatives may exhibit less toxicity but are still irritating agents. Of course, concentration and duration of treatment determine the extent of side effects of the preservatives. High content hydrogel contact lenses absorb BAK molecules and release them slowly onto the corneal epithelium over time. So, patients that use contact lenses may wear those better 15 minutes after the medication. The prolonged exposure to BAK is well known to increase symptoms of ocular inflammation. A diminish of patient's life quality is observed and patient compliance to the specific anti-glaucoma medication, is also undermined. Conversely, there are more causes of dry eye in glaucoma patients, as the majority of the glaucomatous patients are elderly. Such factor is the decrease of tear production with increasing of age and numerous changes in the composition of the tear film. At the same time, elderly often suffer from other pathological diseases that encourage the development of dry eye and eye irritations. Adding the anti-glaucoma eye drops containing preservatives along with the constant use of contact lenses, we are led to a serious multifactorial dry eye condition. The last years several antiglaucoma agents have been marketed such as preservative-free or Benzalkonium chloride-free formulations in an attempt to reduce the side effects related to the preservatives.