Osmolality and tear film dynamics

Authors

  • Ulrike Stahl PhD,

    Corresponding author
    1. Vision Cooperative Research Centre, Sydney, Australia
    2. School of Optometry and Vision Sciences, University of New South Wales, Sydney, Australia
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  • Mark Willcox PhD,

    1. Vision Cooperative Research Centre, Sydney, Australia
    2. School of Optometry and Vision Sciences, University of New South Wales, Sydney, Australia
    3. Institute for Eye Research, Sydney, Australia. E-mail: u.stahl@unsw.edu.au
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  • Fiona Stapleton PhD

    1. Vision Cooperative Research Centre, Sydney, Australia
    2. School of Optometry and Vision Sciences, University of New South Wales, Sydney, Australia
    3. Institute for Eye Research, Sydney, Australia. E-mail: u.stahl@unsw.edu.au
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Dr Ulrike Stahl, School of Optometry and Vision Science, Level 3, Rupert Myers Building, University of New South Wales, Kensington NSW 2052, AUSTRALIA. E-mail: u.stahl@unsw.edu.au

Abstract

The tear film is a nourishing, lubricating and protecting layer that bathes the ocular surface. It is continuously replenished through cycles of production and elimination via evaporation, absorption and drainage. These processes are often referred to as tear film dynamics. Osmolality is an objective clinical measurement that provides insight into the balance of these complex tear film dynamics. Balanced tear production and elimination is vital for tear film integrity, stability and normal osmolality. Imbalances cause alterations of the tear film structure and composition, ultimately leading to tear film instability and measurable tear film hyperosmolality. Elevated tear film osmolality is considered a core mechanism in dry eye, forming the basis of dry eye symptoms and leading to ocular surface damage. Despite its immense potential in the diagnosis of dry eye, tear film osmolality is not commonly assessed. This review will focus on the current knowledge of tear film dynamics and tear film osmolality.

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