Please see our general page on the use of preservatives in eyedrops.
Some very harsh preservatives (e.g. BAK) clearly must be avoided by dry eye patients for ANY eyedrops used on a regular basis. In the case of other, milder preservatives the tradeoffs may be much more equivocal, particularly if an unpreserved version of the product that works best for us is not available. The lack of options available to us dry eye patients is a real problem.
But IMHO, there's no need to throw the proverbial baby out with the preservative bathwater.
I personally - with my limited knowledge - consider the track record of polixetonium to be extraordinarily good. If I had never come across Dr. Holly's drops, it's entirely possible I would now have more inflexible views on preservatives. But I've been a most grateful beneficiary of these effective AND safe eyedrops for many years now. I'm also closely acquainted with a great number of other users - all people with severe chronic dry eye - who have used the drops with great success for a decade or more, as well as many doctors who have been prescribing them. I noted with interest that Focus Laboratories (who sell FreshKote) claim that polixetonium actually enhances ocular surface wettability, and indeed I had been told before that that the preserved versions of these eyedrops are superior to the unpreserved ones, which is one of the reasons we opted to produce Dwelle/Dakrina/NutraTear in 15mLs rather than unit doses.
I wish I were in a position to better demonstrate the scientific benefits. I understand this preservative is now owned by a major pharmaceutical and I sincerely hope that when they have completed detailed studies on it they adopt it as a preservative for more products instead of BAK.