Humidity and dry eyes

Intensive screen work is very taxing on the eyes: swollen eyelids, redness, foreign body sensation, burning and high sensitivity to light are often the consequences. One of the most common causes of this is inadequate moistening of the surface of the eye with tear fluid.

Dry eyes are one of the most common forms of eye disease and involve all symptoms caused by reduced moistening of the surface of the eye. Also known as “office-eye syndrome”, the symptoms are also produced by climatic and environmental influences: In addition to dust and draughts, humidity is a variable that directly affects the tear film: a humidity level that is too low reduces the eye’s protective tear film.


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Less eye strain with the right humidity

There are many factors that work together to produce problems with the voice: aside from causes specific to individuals (e.g. poor speaking technique), these are mainly factors in the working environment such as loud background noise, a poor indoor climate or an incorrect posture while sitting. The climate, and in particular the humidity of the climate, has a critical influence on the voice: to maintain good voice function and prevent voice disorders, adequate moistening of the mucous membranes is necessary. When we speak, air is pushed out of the lungs through the larynx. This causes the vocal folds to vibrate and, like the strings of a guitar, to produce tones. If the humidity is too low, the mucous membranes of the vocal folds lose their optimum moisture level, and hence their elasticity. The glottis can no longer be fully closed by the vocal folds after breathing in. Additional air finds its way into the vocal tract, leading to irritation, inflammation, and in the worst case loss of the voice.


Two effects of dry air on the tear film

Analysis of scientific work shows that when the humidity level is too low, both the production of tear film and the quality of tear film change. With dry eyes, it is not only the volume of the tear fluid but also its changed composition that causes disruption to the moistening of the surface of the eye. The tear film is made up of several layers. A mucous layer lies directly on the surface of the eye. This ensures that the aqueous layer, which constitutes most of the tear fluid, does not run off and evaporate as quickly as it otherwise would. Studies show that compared to an ideal humidity range of 50 to 80%, the cell density of conjunctival goblet cells decreases sharply at low relative humidities below 30%. The goblet cells of the conjunctiva are responsible in particular for producing mucous, which constitutes an important part of the tear film. Insufficient humidity therefore leads not only to faster evaporation of the tear film, but also to reduced mucous production, which serves to protect and maintain the aqueous part of the tear fluid.


Case studies: Humidification and the eyes

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