Dry Eye Exacerbation in Patients Exposed to Desiccating Stress under Controlled Environmental Conditions

PURPOSE: To determine if controlled environmental conditions can induce acute exacerbations of signs and symptoms in dry eye and asymptomatic subjects. DESIGN: Prospective cross-sectional study. METHODS: Nineteen patients with dry eye and 20 asymptomatic controls were exposed to controlled low humidity (5% relative humidity, desiccating environment) for 2 hours in our Controlled Environmental Research Laboratory at the University of Valladolid. The patients completed the Single-Item Score Dry Eye Questionnaire and the following diagnostic tests were performed before and after exposure: tear osmolarity, phenol red thread test, conjunctival hyperemia, fluorescein tear film break-up time, Schirmer test, and ocular surface vital staining. Sixteen molecules in the tears samples were analyzed by multiplex bead analysis. RESULTS: After exposure, the patients and controls had a significant (P <= .003) increase in corneal staining (from 0.68 +/- 0.15 to 1.16 +/- 0.14 and from 0.50 +/- 0.15 to 1.30 +/- 0.19, respectively), significantly decreased (P <= .01) fluorescein tear film break-up time values (from 2.78 +/- 0.56 seconds to 1.94 +/- 0.24 seconds and from 2.81 +/- 0.24 seconds to 2.13 +/- 0.19 seconds, respectively), and significantly increased (P <= .03) matrix metal-proteinase 9 tear levels (from 10 054.4 +/- 7326.6 pg/mL to 25 744.5 +/- 13 212.4 pg/mL and from 10 620.5 +/- 4494.3 pg/mL to 16 398.7 +/- 5538.3 pg/mL, respectively). In the control group, the epidermal growth factor tear levels decreased significantly (P = .007; from 1872.1 +/- 340.7 pg/mL to 1107.1 +/- 173.6 pg/mL), and interleukin 6 levels increased significantly (P < .001; from 29.6 +/- 5.8 pg/mL to 54.3 +/- 8.3 pg/mL) after exposure. CONCLUSIONS: Adult patients with mild-to-moderate dry eye and asymptomatic subjects of similar ages can experience acute exacerbation in an environmental chamber that resembles the sudden worsening that patients with dry eye experience daily. (C) 2014 by Elsevier Inc. All rights reserved.