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Lubricating Eye Drop Comparison using the Nanovea T50 Tribometer

Importance of Testing Eye Drop Solutions

Eye drop solutions are used to alleviate symptoms caused by a range of eye problems. For example, they can be used to treat minor eye irritation (e.g. dryness and redness), delay the onset of glaucoma or treat infections. Eye drop solutions sold over-the-counter are mainly used to treat dryness. Their effectiveness in lubricating the eye can be compared and measured with a coefficient of friction test.
Dry eyes can be caused by a wide range of factors, for example, computer eye strain or being outdoors in extreme weather conditions. Good lubricating eye drops help maintain and supplement the moisture on the outer surface of the eyes. This works to alleviate the discomfort, burning or irritation and redness associated with dry eyes. By measuring the coefficient of friction (COF) of an eye drop solution, its lubricating efficiency and how it compares to other solutions can be determined.

Measurement Objective

In this study, the coefficient of friction (COF) of three different lubricating eye drop solutions was measured using the pin-on-disk setup on the Nanovea T50 Tribometer.

Test Procedure and Procedures

A 6mm diameter spherical pin made of alumina was applied to a glass slide with each eye drop solution acting as the lubricant between the two surfaces. The test parameters used for all experiments are summarized in Table 1 below.

Results and Discussion

The maximum, minimum, and average coefficient of friction values for the three different eye drop solutions tested are tabulated in Table 2 below. The COF v. Revolutions graphs for each eye drop solution are depicted in Figures 2-4. The COF during each test remained relatively constant for most of the total test duration. Sample A had the lowest average COF indicating it had the best lubrication properties.



In this study we showcase the capability of the Nanovea T50 Tribometer in measuring the coefficient of friction of three eye drop solutions. Based on these values, we show that Sample A had a lower coefficient of friction and therefore exhibits better lubrication in comparison to the other two samples.

Nanovea Tribometers offers precise and repeatable wear and friction testing using ISO and ASTM compliant rotative and linear modules. It also provides optional high temperature wear, lubrication, and tribo-corrosion modules available in one pre-integrated system. Such versatility allows users to better simulate the real application environment and improve fundamental understanding of the wear mechanism and tribological characteristics of various materials.