Correlations in a change in aqueous tear evaporation with a change in relative humidity and the impact.
OBJECTIVE
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.


METHODS
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).
McCulley
James P
JP
Department of Ophthalmology, The University of Texas Southwestern Medical Center, Dallas, Texas 75390-9057, USA. james.mcculley@utsouthwestern.edu
Aronowicz
Joel D
JD
Uchiyama
Eduardo
E
Shine
Ward E
WE
Butovich
Igor A
IA
D003941:Diagnostic Techniques, Ophthalmological; D015352:Dry Eye Syndromes / Q000378:metabolism*; D005260:Female; D006801:Humans; D006813:Humidity; D008297:Male; D008875:Middle Aged; D009799:Ocular Physiological Phenomena; D011446:Prospective Studies; D013666:Tears / Q000378:metabolism*; D014835:Volatilization; D014867:Water / Q000378:metabolism*
D014867:Water