Editing Eye drop (section)

== Shelf life ==
Although most bottles of eye drops contain preservatives to inhibit contamination once opened, these will not prevent contamination indefinitely. Ophthalmologists recommend keeping bottles for no longer than three months after opening.<ref name="Shelf-life of Eye Drops">{{cite web|title=Shelf-life of Eye Drops|url=http://www.aao.org/eye-health/ask-ophthalmologist-q/eye-drop-shelf-life|website=American Academy of Ophthalmology|access-date=31 October 2016|date=10 March 2014}}</ref> Eye drops that contain no preservatives are usually packaged in single-use tubes.  Dispensers typically oversize the drops; the human eye can only handle about 25 microlitres.<ref>{{cite news|last1=Allen|first1=Marshall|title=Drug Companies Make Eyedrops Too Big, And You Pay For The Waste|url=https://www.npr.org/sections/health-shots/2017/10/18/558358137/drug-companies-make-eyedrops-too-big-and-you-pay-for-the-waste|access-date=20 October 2017|work=[[NPR]]|date=18 October 2017}}</ref>