@beehive54 thanks for that info I just got off phone with pharmacy clerk and she basically said the same thing, but I sure was confused for a while....especially since I have sort of vouched for the fact Monoprost has no preservative, then to read recently that it contains Latanoprost and on my pharmacy receipt actually says Monoprost/Latanoprost I was surprised... especially since recently after taking an antibiotic I seem to have "visual snow" and wondered if a link, but have used these drops for 5 yrs. Wonder why Latanoprost then still manufactures drops named Latanoprost ... with benzalkonium chloride preservative in , considering its bad effects esp. on eyes? I still think would like to make a change but seems most glaucoma drops have their own set of side effects.... "it it what it is" as they say! J.