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Nhi Nguyen, Daniel Russell Powell; IMPACT OF A LOW HUMIDITY ENVIRONMENT ON TEAR FILM STABILITY AND VISUAL PERFORMANCE. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2702. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate the effects of exposure to a desiccating stress on 1) ocular comfort, 2) ocular surface health and 3) visual performance (VP).
Healthy, non-contact lens wearers 18 years of age and older participated. The following were conducted before and after subjects were in an environmental chamber for 1.5hrs. (temperature 74.5F; humidity 4.3% ): one-item eye comfort visual analog scale; near Snellen and high and low contrast distance (logMAR) visual acuity (VA); standardized IReST reading card to assess reading speed and accuracy; higher-order aberrations (HOA; Topcon KR-1W); tear film lipid layer thickness (TFLLT; LipiView); mean non-invasive tear break up time measured three times with the Keratograph5 (NIKBUT); bulbar conjunctival hyperemia (BCH) assessment on a 0-4 scale; corneal fluorescein staining grading in three regions (superior, inferior, central) using a modified Efron scale 2min. after instillation of 5μL fluorescein. Nonparametric statistics analyzed all outcomes.
Seventeen subjects participated (27.5±10.9 years, 58% female). Eye comfort scores decreased two-fold (p=0.009). No changes were noted for VA, TFLLT and NIKBUT (all p>0.22). Reading speed increased slightly but reading errors nearly doubled (p=0.02). BCH and corneal staining increased by 0.5 and 1.0 points, respectively (both p≤0.004). Spherical aberration and overall HOA increased (both p≤0.02).
Subjects were more likely to report decreased eye comfort after exposure to a dry environment. Increased BCH is often observed after exposure to an environmental stressor. Evidence suggests VP may be affected given increased HOAs and ocular surface injury despite a nominal decrease in VA. Increased reading errors may also suggest a decrease in reading fluency. Evaluation of more sensitive measures of visual status (contrast sensitivity) and the recruitment of dry eye subjects (to see if they are more susceptible to decreased comfort and VP) should be the focus of future studies.
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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