Watery eyes: when tears flow

We do not only cry when we are sad. Tears also flow when we laugh or slice onions. If eyes run very frequently and excessively without an obvious reason, however, this can be quite annoying – not only because maybe your mascara is running but also because your eyesight is impaired. In addition, it is simply uncomfortable if your eyes become wet at inappropriate moments. Watery eyes are also referred to as epiphora. Watery eyes can be an indication of various diseases and symptoms – dry eyes are one of them.

Watery eyes: dryness of the eye can be the cause

Dry eyes can be a cause for watery eyes – a fact which one would not immediately think of when looking for the cause of watery eyes. There could be two reasons for why the tears are flowing: too much lacrimal fluid or an incorrect composition of the lacrimal fluid.

Increased tear productsion

With watery eyes, it could be that the amount of lacrimal fluid produced within a given period is too great. The reason for this: if the cornea is not lubricated enough with liquid due to the eye being dry, the opening and closing of the eyelid produces friction on the surface of the eye. The lacrimal glands react to that by producing more tears in order to compensate for the lack of moisture. The surface of the eye can, however, only absorb and hold a certain amount of fluid. If the accumulated volume is too great, the superfluous lacrimal fluid flows out of the eyes. In this case, the adjustment of tear productsion to the actual tear requirement is dysfunctional.

Incorrect tear composition

On the other hand, the incorrect composition of the tears can be responsible for unstable tear film and watery eyes. The tear film lubricates the surface of our eyes and is composed of three layers. Directly above the cornea lies a thin film of mucous, known as the mucin layer, which covers the entire surface of the eye. It ensures that the fluid remains adhered to the eye, does not roll off and spreads out evenly. Above that there is a thicker, watery layer of tears. The tear film is held together by an upper, very oily layer. This third layer provides stability for the film of fluid so that it does not flow off or evaporate.

If, for health reasons, the lacrimal fluid does not have the correct composition, it is possible that the three layers of eye lubrication will not be stable and will not hold together. This is particularly the case with disruptions of the oily layer, for example with a meibomian gland dysfunction, in which the glands in the eyelid margin function inadequately. The eyes then start to water.

Other reasons for watery eyes

Watery eyes can be caused by something other than dry eyes. For example, if the eyes are irritated by various environmental influences or foreign bodies, they also react with an increase in tear productsion, in order to rinse possible irritants out of the eye. This could be the case with irritation due to dust, dry air, fluff or tiny hairs. This mechanism also plays a big role with intolerances and allergies: the eye reacts to what are really harmless substances, such as pollen, by producing large volumes of tears.

Finally, various illnesses or injuries could lead to watery eyes. Inflammation of the cornea or conjunctiva or sinusitis is often accompanied by watery eyes. Disruption of normal tear drainage can also produce watery eyes. If the eyes water frequently or unusually strongly, an eye doctor should establish the cause. If dry eyes are the cause, it often helps to use eye drops which are developed for the cause of the dryness.