“Preservative-Free”
Regener-eyes
Regener-Eyes Professional Strength and LITE both clearly state on their packaging that they are preservative-free, and this is a widely-advertised feature.
regenereyes.com/our-products
StimulEyes
M2Biologics does not appear to state anywhere that StimulEyes is preservative-free. Following is the only reference to preservatives that we have found. This reference is somewhat ironic in fact, because the presence of preservatives would render the proteins inactive, so preservatives are not actually an option.