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Contact lenses, those handy-dandy little vision aids, make the difference for 28 million people between seeing clearly in all directions, or being confined to inconvenient and distorting eyeglasses or worse. With the many choices and technological advances available these days, contact lenses should continue to benefit millions of people who have less-than-perfect vision.
Here's the catch: While a few contact lens users are able to wear their lenses for days or weeks at a time with no problem, such individuals are the exception. Many people can tolerate contact lenses only for short periods, and many cannot tolerate them at all. Even for those who tolerate them reasonably well, lenses frequently cause discomfort. This article will suggest a way to soothe much of the eye discomfort caused by contact lenses:
The main thing to know about contact lenses is that they float on the surface of the delicate and complex tear film that covers the exposed parts of the eyeball, and they rely on the tear film's moisture (water content) to maintain their pliability, integrity and adherence. The surface tension of the tear film's moisture against the lenses prevents them from falling out.
The problem is that the most popular types of lenses deplete the tear film's moisture content and therefore interfere with healthy tear film functioning. Soft lenses, and gas permeable lenses, have been compared to miniature sponges because of the amount of tear film moisture they soak up. Even rigid lenses deplete some tear film moisture. In addition, all lenses, even gas permeable, reduce the amount of oxygen reaching the corneal surface. Rigid lenses restrict oxygen the most, which is one reason they are smaller.
The tear film that covers the exposed optical surface is amazingly complex, considering that it is only about five microns (millionths of a meter) thick. Tear film components:
Lipid layer. This topmost layer is comprised of a very thin film of fatty oil that lubricates the eyelid and slows moisture evaporation from the lower layers.
Aqueous layer. The middle and thickest layer contains the vast majority of the tear film's moisture. This is where most moisture loss occurs. The layer also contains electrolytes, proteins and bacteria-fighting antibodies. It provides oxygenated water to allow the cornea to breathe.
Mucin layer. This bottom layer glues the tear film to the optical surface.
When tear film moisture is depleted, the resulting abnormal changes can make the eyes feel uncomfortable. The most physically irritating results of tear film moisture loss are an over-concentration of electrolyte (salt) and proteins in the aqueous layer. Insufficient oxygen in the aqueous layer's moisture can also cause discomfort. Discomfort can include itching, burning, irritation, eyestrain, headache, etc.
Soothing dry, irritated eyes, whether caused by contact lenses, environmental conditions or bodily dehydration from illness or stress, is a simple and logical tear film cross section procedure: Simply add moisture to the tear film! In the past 110 years of medical eye care research, however, this has proved more easily said than done.
One problem has been getting the moisture past the overlying lipid layer. As it turns out, our eyes already know how to accomplish this trick. The tear film is perfectly capable of extracting all the moisture it needs from the humidity in the air, provided the air is reasonably humid (70% at 70 degrees), and the humidity droplets are pure and unpolluted.
However…the standard solution to the problem of dry, irritated eyes has been not humidity but eyedrops. Since eyedrops rely on chemical formulations and eyedroppers, they pose numerous drawbacks. The typical eyedrop is ten times larger than the volume of the tear film. When applied, the drop may flood and wash away the natural tear film, including the evaporation-retarding lipid layer. Despite their complex chemistry, formulated eyedrops invariably lack one thing: The minute quantity of pure, natural, pH-balanced water that is all the tear film really needs.
In 2002, Bio-Logic Aqua Technologies Biomedical Research introduced Nature's Tears EyeMist, the first effective, all-natural alternative to formulated eyedrops for dry, irritated eyes. For the first time, millions of contact lens wearers are obtaining instant relief from dry, irritated eyes…without eyedrops.
Nature's Tears EyeMist solved the problem of getting moisture in extremely minute quantities past the lipid layer into the aqueous layer. This is accomplished very simply, by delivering the moisture as an ultra-pure, ultra-fine mist that emulates the air's natural humidity. The mist is sprayed towards the face rather than into the eyes, enabling the tear film to extract exactly as much moisture as it needs, no more and no less. In most cases, all that is required to restore the tear film's moisture content to full volume and comfort, is two to five nanoliters (billionths of a liter). That is far too little to apply with an eyedropper.
As an added benefit, delivering moisture in the form of a mist oxygenates the moisture, thus increasing the aqueous layer's oxygen content.
The most beneficial component of eyedrops is the paraffin or oil that can serve as a sealer to slow tear film moisture loss. Eyedrops are most effective as a moisture sealer when the tear film's moisture content is at full capacity. For best results, apply Nature's Tears EyeMist immediately before applying eyedrops, and use the smallest amount of eyedrops possible. Since Nature's Tears EyeMist has no dosage limit, it may also be applied between eyedrop applications, or when eyedrops are not convenient.