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Brandon Gregory DeCaluwe, Christine Callan, Geunyoung Yoon, Holly Butler Hindman; The relationship between ocular surface temperature and tear film lipid heterogeneity. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2695.
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© ARVO (1962-2015); The Authors (2016-present)
Although tear film instability has been identified as a common mechanism of dry eye disease (Stern et al., 1998), there is a paucity of research into how biological and physical changes interact to affect the tear film. To address this gap in the literature, we performed a retrospective study to investigate whether changes in ocular surface temperature predict tear film lipid heterogeneity.
This study was a secondary analysis of data collected in the environmentally controlled chamber at the Flaum Eye Institute’s ocular surface laboratory. The sample included a mixture of 39 normal and dry eyes. Data collected from participants included age, sex, lipid thickness, lipid heterogeneity, and percent change in ocular surface temperature (OST) over a single blink. OST was measured on a standard area of the central cornea on a fully opened eye, upon opening of the eye and immediately prior to lid closure. Lipid thickness and heterogeneity were analyzed over a standard region of interest, over the lower half of the corneal surface outside the pupil. Hierarchical linear regression was used to determine whether percent change in ocular surface temperature predicts average lipid heterogeneity after controlling for lipid thickness.
Descriptive statistics for study variables are presented in Table 1. Controlling for lipid thickness, percent change in ocular surface temperature over the blink significantly predicted average lipid heterogeneity (R2 = .472, ΔR2 = .086, p = .021), such that the greater the decrease in temperature over the blink, the greater the lipid heterogeneity (β = -.296, p = .021).
Prior research has shown that meibum is sensitive to temperature, thickening and solidifying at lower temperatures (Lu, Wojtowicz, & Butovich, 2013). We conclude that a decrease in ocular surface temperature over the blink induces lipid layer clumping, as demonstrated by increased lipid heterogeneity. Lipid clumping during the blink interval may increase tear evaporation and destabilize the tear film smoothness. Future research should investigate whether this deterioration in the smoothness of the tear film secondary to heterogeneous clumping leads to symptomatic dry eye and visual deterioration.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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