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Benjamin Lee, Misha Faustina; Eyelid Temperature and Tear Osmolarity. Invest. Ophthalmol. Vis. Sci. 2017;58(8):442.
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© ARVO (1962-2015); The Authors (2016-present)
The effect of direct non-pulsatile external eyelid heat application on tear osmolarity has not previously been documented. We performed a retrospective cohort study to quantify how different eyelid temperatures achieved from externally applied heat may change patient tear osmolarity.
Clinic charts of 16 patients with dry eye syndrome treated with externally applied eyelid heat were retrospectively reviewed. None of the patients had known lacrimal dysfunction. According to clinic treatment protocol, patients’ baseline tear osmolarity in the right eye was measured using the TearLab® Osmolarity System. Patients then received 10 minutes of direct non-pulsatile externally applied heat on the eyelids with the Digital Heat™ Precision Heated Eye Pad. After 10 minutes, the heated eye pad was removed with eyelids remaining closed to obtain a non-contact spot temperature measurement using the FLIR i7™ Thermal Imaging Camera. Following, patients opened their eyes for the immediate measurement of post-heat tear osmolarity in the right eye.
Eyelids had temperature measurements ranging from 39.3 C○ to 42.6 C○ as a result of externally applied heat. Using a paired two sample t-test, the right eye of patients exhibited significantly lower mean tear osmolarity after 10 minutes of applied heat (319.25±16.36 Osm/L vs 304.69±11.36 Osm/L in baseline and post-heat tears, p<0.001 for two tail) with Cohen’s size effect (d=1.03, 95% CI=0.29-1.77). The mean arithmetic tear osmolarity difference between tear osmolarity at baseline and post-heat was 14.56±12.47 Osm/L. Furthermore, Pearson correlation coefficient showed a significant negative correlation between the temperature measured on the right eyelid at 10 minutes and the associated arithmetic tear osmolarity difference (r=-0.509, p=0.044 for two tail).
Applying heat on the eyelid for 10 minutes resulted in various levels of achieved eyelid temperatures that decreased tear osmolarity. The associated large Cohen’s effect size supports this finding. The negative correlation finding suggests that higher achieved eyelid temperatures may result in smaller decreases in tear osmolarity. Taken as a whole, there probably exists an optimal eyelid temperature range achieved from externally applied heat on the eyelids and length of treatment time to most effectively lower tear osmolarity. These are topics for further evaluation.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
Sample of thermal image immediately following removal of Heated Eye Pad.
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