Published: Apr 2013 | PMID: 23023409 DOI: 10.1097/ICO.0b013e31826671ab

The effect of low humidity on the human tear film

Abusharha AA, Pearce EI.


The authors investigated the effect of dry air on tear film physiology. 12 young subjects (10 m., 2 f., mean age 29,8 y) with no history of dry eye syndrome were exposed during 60 minutes to very low relative humidity (RH) of 5% compared to 40%RH in an environmental chamber.


There was significant change in tear evaporation rate (P = 0.00), noninvasive tear break-up time (P = 0.00), Lipid Layer Thickness LLT (P = 0.00), ocular comfort (P = 0.00), and tear production (P = 0.01) after exposure to the desiccating environment. No significant differences were observed between normal and dry environmental conditions in tear osmolarity (P = 0.09) and ocular surface temperature (P = 0.20).


Evaporation rate, tear lipid layer thickness, ocular comfort, tear stability, and production were adversely affected by low RH. The tear film parameters observed after exposure to a desiccating environment for 1 hour were similar to those of the dry eye patient.

Therefore, to avoid tear film disruption and possible ocular surface damage, the environmental conditions of dry locations need to be improved or the tear film should be protected against adverse environmental conditions.

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Doc's view...

by Walter Hugentobler

Our eye's precorneal tear film helps keep our eyes healthy and our vision clear.

This study shows that exposure to a dry atmosphere, detrimentally affects our precorneal tear film.

This reinforces the need to maintain indoor humidity at above 40%RH, especially in office environments, where people are using VDUs that put additional strain on the eye.

Indoor office environments typically drop below 40%RH during the winter when dry outdoor air is heated, resulting in a low indoor humidity. However, these conditions can also occur in air conditioned offices during the summer, as moisture is removed from the air during the cooling process.

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