Repeatability of a new method for measuring tear evaporation rates

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Environmental Science

Background:

• Tear evaporimetry is crucial for diagnosing dry eye disease.
• Infrared thermography offers a non-invasive method to assess ocular surface parameters.

Purpose of the Study:

• Evaluate the repeatability of tear evaporimetry using infrared thermography in a clinical setting.
• Investigate the impact of varying environmental humidity on ocular surface temperature (OST) and tear evaporation rates (TERs) within a controlled adverse environment (CAE) chamber.

Main Methods:

• Twenty-six healthy participants underwent repeatability testing in a clinical room and humidity exposure in a CAE chamber (30°C, 45% and 65% humidity).
• Ocular surface temperatures (OSTs) and tear evaporation rates (TERs) were measured using infrared thermography.
• Tear film breakup time and blink rate were also assessed.

Main Results:

• Tear evaporimetry demonstrated acceptable repeatability for OST and TERs (coefficients of repeatability: 0.4°C and 6.0 W m, respectively).
• Increased humidity (45% to 65%) significantly elevated OST (p < 0.05) but did not significantly alter TERs (p > 0.05).
• Tear film breakup time and blink rate remained unaffected by humidity changes.

Conclusions:

• Infrared thermography-based tear evaporimetry is a repeatable technique for clinical use.
• This method shows potential for tracking individual tear evaporation changes, particularly in environments with humidity variations under 20%.