Tearing Eyes

all articles below were personally written by Dr. Chang

Many patients over the age of 50 complain that their eyes frequently water. Although these symptoms are not serious, they are annoying and irritating. The most common cause of this sudden watering is an "unstable tear film".

Unlike the rest of the body, there is no skin covering the external surface of the eyeball. Although the upper and lower lids cover part of the eyeball, the rest of the surface is exposed to the environment all day long. Potential irritants include dust, pollen, smog, smoke, wind, and sunlight.

Protecting our eye surface from these elements is a thin layer of viscous tears, called the "tear film". This lubricates and protects the eye surface, much like saliva does for our mouth. The purpose of blinking is to constantly spread a new tear film over the eye surface.

With age, the quality of the "tear film" diminishes, and it tends to evaporate more easily. Small dry spots form, and these exposed areas of the eye surface become slightly irritated. This causes a reflex watering to occur. The watery, runny tears rinse the eye, but do not lubricate it. As an analogy, water rinses our mouth, but does not coat and lubricate the inside of our mouth in the way that saliva does.

This explains why the sudden tearing occurs during certain activities. Evaporation is more likely in outdoor, windy environments, and with air currents caused by fans and vents. Activities that cause us to stare, such as reading and driving, will cause momentary evaporation of the tear film, and reflex watering. None of these activities or situations are harmful. They only serve to irritate eyes with a poor tear film. Other symptoms of a poor tear film include redness, burning, itching, and a sandy or scratchy feeling.

Although treatment is not of medical importance, artificial tears can provide some relief. These are over the counter drops that lubricate the eye and augment our natural tear film. They contain no medicine and, unlike water, they lubricate rather than rinse the eye surface. They can be used up to four times a day, and are best instilled immediately before or after activities that provoke the watering (e.g. outdoor exercise, prolonged reading, etc.) These drops are available over the counter without a prescription. There is no one superior brand among the dozen or so that are available. Like choosing a soap or shampoo, patients can follow their own preferences.

All bottles of eye drops contain a small amount of chemical, called a "preservative". This prevents germs from growing inside the bottle during the weeks after the original seal is opened. If one averages more than four drops of artificial tears daily, it is preferable to use unpreserved tears, to avoid potential irritation from excessive amounts of this chemical preservative. Unpreserved artificial tears are more expensive since they require disposable packaging. These tiny vials contain a small number of drops that will be used up within a day or two, and therefore do not require a preservative inside.