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Updated: Aug 9, 2026

Effect of Artificial Tear Formulations on the Metabolic Activity of Human Corneal Epithelial Cells after Exposure to Desiccation
Published on: May 2, 2020
Correlations in a change in aqueous tear evaporation with a change in relative humidity and the impact
James P McCulley1, Joel D Aronowicz, Eduardo Uchiyama
1Department of Ophthalmology, The University of Texas Southwestern Medical Center, Dallas, Texas 75390-9057, USA. james.mcculley@utsouthwestern.edu
Purpose:
To establish scientific relationship between relative humidity (RH) and aqueous tear evaporation to elucidate possible significance of this relationship in normals and aqueous tear deficiency patients.
Design:
Prospective experimental laboratory study.
Methods:
Ocular surface evaporation was determined using evaporometry and calculated for two ranges of RH, 25% to 35%, and 35% to 45% in a randomized clinical patient population.
Results:
Average evaporative rate in the higher humidity range was between 0.029 +/- 0.009 through 0.043 +/- 0.016 microl/cm2/min. At lower humidity, range was between 0.044 +/- 0.013 through 0.058 +/- 0.018 microl/cm2/min. Differences in the corresponding evaporative rates were statistically significant (between P < .003 through P < .043) for each analysis.
Conclusions:
A decrease of 10% RH resulted in an average difference of between 28.33% to 59.42% increase in evaporation. The increase in evaporation at lower humidity has significant clinical implications for patients with aqueous deficient dry eyes, and possibly those undergoing laser-assisted in situ keratomileusis (LASIK).
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