Preservatives in Eye Drops

Recently my choice of eye drops has done little to quench the thirst that my eyes long for. After about 20 minutes or so, I would have to insert more drops and do so over and over. I am quite careful of what I insert into my eyes and try to stay away from eye drops with preservatives as much as possible.

I never realized this, but someone on a forum mentioned that TheraTears in bottle form contains a preservative. However, it disappears the moment it touches your eyes.

What's wrong with preservatives, you ask?
Well most eye drops on the market seem to contain benzalkonium chloride (BAK), and in laboratory tests have shown to consist of toxic effects. If your eye doctor states that you should use eye drops with perservatives/steroids than you should do so under their care.

Provided are several links that give a good overview of preservatives and what to be careful of:

Preservatives Explained (dryeyezone.com)
Preservatives: The good, the bad and the ugly (pubmed.gov)