A nanoliter of water is not very much. A "nano" of anything is not very much. A nanosecond is not very much. Neither is a nanogram. The prefix "nano" means "one billionth", although the name actually comes from the Greek word "nanos", meaning "dwarf". So a nanoliter is one-billionth of a liter and a nanogram is a billionth of a gram.

If you had a glass containing five nanoliters of water, it would appear completely dry and empty. Five nanoliters are not visible to the naked eye (or to the clothed eye). If there was a teensy drop of visible water clinging to the side of your glass, that drop would contain ten to twenty microliters (millionths of a liter), or two to four thousand times as much as a five nanoliter drop. Neither would come close to quenching your thirst.

And yet, do not underestimate the power of the nanoliter. Or of five nanoliters. Believe it or not, when your eyes are dry and irritated due to water evaporation from their tear film covering (the "tear film" is the thin layer of salt water, oil and mucus over your eyeball's external surface), the addition of only five nanoliters of water can make the difference between comfort and clear vision, and eyes that are tired, itching and burning.

The bad news is that applying a five nanoliter drop to the eye would require a dropper so narrow and needle-sharp that sticking it in your eye would be dangerous (in fact, sticking a regular eyedropper in your eye can be dangerous). The government strictly regulates the size of pharmaceutical objects intended to be stuck in the eye. They won't allow anything smaller than the standard eyedropper most people are familiar with, which delivers far more fluid than even the most dehydrated tear film could ever utilize.

When an eyedrop inserted into the eye is too big, all sorts of unfortunate things happen. Instead of adding water to the existing natural tear film, the tear film is flooded, washed away and replaced by the chemical eyedrop. Also washed away are a microscopic oil (lipid) layer that slows the evaporation of water from the tear film, and antibodies that defend against infection. That's why too-frequent use of eyedrops is not recommended.

There is only one commercial eye care product capable of delivering moisture to the eye in nanoliters amounts, or what doctors call a "titratable dose". A titratable dose is the smallest dose required to yield a benefit. In the case of dry eye, a titratable dose is three to five nanoliters.

The product is Nature's Tears EyeMist^®, the only eye care product applied as an ultra fine mist rather than as drops. You cannot flood your tear film with Nature's Tears EyeMist^® because guess what? The water is not inserted into the eyes, it is floated in the air front of the eyes (try to make a regular eyedrop float!). The eyes then use their natural moisture-absorbing ability to extract exactly as much as they need - be it one nanoliter or ten nanoliters - no more and no less.

Unlike eyedrops, there is no danger in misting too frequently. In fact, the more often you mist, the better it is for your eyes. Studies have shown that dry eye symptoms can actually be prevented by the use of Nature's Tears EyeMist^®. It's amazing what a couple of extra nanoliters can accomplish.