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C. J. Maffei, G. W. Ousler, III, D. L. Welch, S. J. Curwen, E. Prifogle, M. B. Abelson; Time to Reflex Tearing in Response to Chemical Nasolacrimal Stimulus in Dry Eye Subjects versus Normals. Invest. Ophthalmol. Vis. Sci. 2010;51(13):3398.
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We’ve previously shown the ability of the Controlled Adverse Environment (CAE model) to differentiate normals and dry eye patients based on time to reflex tearing. This research demonstrated a longer time to reflex tearing with increasing dry eye severity. Based on knowledge that nasal mucosal stimulation promotes tear production, the present study investigated the potential utility of chemical nasal mucosal stimulation in differentiating the two populations as well.
11 normal subjects and 10 subjects diagnosed with dry eye were evaluated. After careful instruction to indicate the first sensation of tearing, an open vial containing the chemical stimulant, dilute ammonia, was introduced approximately 5 cm away from the subject’s nose. A stopwatch was used to record the time from introduction of the chemical nasolacrimal stimulus to subject-reported tearing.
Subjects with dry eye demonstrated a time to reflex tearing of 9.26 ± 4.54 seconds compared to normal values of 4.54 ± 2.20 seconds. The observed time to reflex tearing in subjects with dry eye demonstrated significantly longer time to reflex tearing compared to normals (P = 0.017).
These results demonstrated that subjects with dry eye exhibit a delayed reflex tearing response. These findings suggest that dry eye patients may have decreased protective mechanisms in response to chemical irritants. Furthermore, these findings may have implications for the impact of environmental irritants on subjects with compromised tear film barrier capabilities and warrant further investigation.
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