There are many eyedrops in "single-use vials" which are common used by people with dry eye, from OTC preservative-free lubricants to Restasis. Most are so costly and entail so much waste if used only once that they are often re-used. Many doctors support such re-use and some manufacturers may as well. In the early days of Restasis I seem to recall they even provided a little contraption to store them safely for re-use. We see debates now and then on the bulletin board as to whether refrigeration is appropriate.
This study basically says that for a vial of Refresh Plus (pretty much the most commonly used artificial tear on the market), if the common bacterium pseudomonas aeruginosa gets in it, it will thrive and could do some nasty things to your cornea. Not good.
At the very least this sounds like a cautionary word for users of unpreserved carboxymethylcellulose-based artificial tears, i.e. if you're re-using them, you may want to reconsider. I would be interested to know of it has implications for other polymer-based unpreserved drops. This is certainly enough to make me reconsider whether I suggest to anyone that they carefully re-use vials.
Pseudomonas aeruginosa Growth in Refresh Plus(®).
To assess Pseudomonas aeruginosa growth in Refresh Plus(®), a unit-dose preservative-free ophthalmic solution indicated for the treatment of dry eye and after laser-assisted in situ keratomileusis (LASIK) surgery, which contains carboxymethylcellulose 0.5% as its active ingredient.
Multiple test tubes of Refresh Plus were inoculated with 3 clinical ocular isolates of P. aeruginosa to achieve a target concentration of ∼100 colony-forming units (CFU)/mL. The tubes were incubated at 25°C and samples were aseptically removed at 6, 12, and 24 h. The samples were cultured to enumerate the population at each time point.
After 6 h incubation, the number of CFU/mL was 3,200 for isolate 1, 2,000 for isolate 2, and 6,480 CFU/mL for isolate 3. For all 3 organisms tested, the number of CFU/mL after 12 and 24 h incubation was >10(6) CFU/mL.
Under the conditions of this experiment, Refresh Plus appears to support P. aeruginosa growth, suggesting that if the solution in a unit-dose vial of Refresh Plus were contaminated with P. aeruginosa during use, the organism would survive and replicate in the solution over time. Noncompliance with the manufacturer's recommendations (i.e., reuse of an open vial) may result in contamination of the solution with P. aeruginosa, which may cause severe keratitis.
J Ocul Pharmacol Ther. 2011 Aug 12. [Epub ahead of print]
Pinna A, Usai D, Zanetti S.
1 Section of Ophthalmology, Department of Surgery, Microsurgery, and Medico-surgical Specialties, University of Sassari , Sassari, Italy .