Human Ocular Surface Particulate Composition in the Clinical Versus Home Environment

PURPOSE: Our eyes are chronically exposed to airborne particulate matter shown to adversely affect the ocular surface. This research examines size, type (organic vs. inorganic), and elemental composition of particles recovered from the ocular surface in 2 environments and their associations with dry eye (DE) metrics. METHODS: Particles were recovered from the right eye using Schirmer strips obtained both in the clinic and home environments 9 ± 8 days apart. Particle size and elemental composition were assessed using scanning electron microscopy and energy dispersive spectroscopy. The paired t test was used to evaluate the differences in the size and types of ocular surface particles recovered from the clinic and home settings. Associations of particle size and type with home environmental conditions and DE measures were evaluated using correlation analyses. RESULTS: The mean age of the 15 patients was 56 years, standard deviation (±) 12 years; 93% were men and 53% self-identified as white. Size, type, and elemental composition did not vary significantly between clinic and home. Particle surface area was marginally associated with home indoor temperature (25 °C ± 2, ρ=-0.53, P = 0.06) and significantly associated with the select DE signs: tear osmolality (304 mOsm/L ± 14, ρ= -0.60, P = 0.02), inflammation (0.7 ± 0.8, ρ = 0.53, P = 0.04), and tear breakup time (7 seconds ± 3, ρ = 0.56, P = 0.03). CONCLUSIONS: Ocular surface particles were consistently detected across 2 different environments. Greater particle area detected on Schirmer strips correlated with some DE measures, suggesting that particles detected on the ocular surface may affect eye health.