Related Experiment Video
Updated: May 20, 2026
09:04
Optimizing Tear Collection in Mice for mRNA and Protein Analysis
Published on: July 19, 2024
Estimating tear film spread and stability through tear hydrodynamics
Jalaiah Varikooty1, Nancy Keir, Trefford Simpson
1Centre for Contact Lens Research, University of Waterloo, Waterloo, Ontario, Canada. jpvariko@uwaterloo.ca
Summary
This study introduces a novel method to measure tear-film spread on contact lenses using particle dynamics. This technique offers a simpler, objective assessment of tear-film stability in vivo.
Area of Science:
- Ophthalmology
- Biomedical Engineering
- Surface Science
Background:
- Assessing tear-film stability on contact lenses is crucial for understanding lens performance and wearer comfort.
- Current in vivo methods for determining lens dewetting and tear-film spread are often complex and invasive.
- There is a need for objective, non-invasive techniques to evaluate tear-film dynamics on contact lenses.
Purpose of the Study:
- To introduce and validate a novel, objective method for measuring the upward spread and stability of the tear-film over soft contact lenses in vivo.
- To assess tear-film particle dynamics as an indicator of tear-film dewetting and spread on contact lenses.
- To establish a simpler alternative to existing complex methods for evaluating tear-film behavior on contact lenses.
Main Methods:
- Ten adapted soft contact lens wearers participated in the study.
- Tear-film spread was recorded using a slit-lamp mounted video camera at 8x magnification and 30 frames per second.
- Particle tracking analysis using a customized ImageJ macro was employed to determine the velocity of reflective tear-film particles.
- Data were analyzed using R and ProFit software.
Main Results:
- Upward particle velocity, indicative of tear-film spread, was highest immediately after blinking and decreased over time.
- Significant differences in tear-film spread (measured by upward particle velocity) were observed between lens insertion and after 8 hours of wear (p = 0.001).
- Exponential time constants for tear-film spread differed significantly between initial lens insertion (346.02 ± 29.0) and after 8 hours of wear (1413.13 ± 419.6).
Conclusions:
- A novel, non-invasive method utilizing tear-film particle dynamics for measuring in vivo pre-lens tear-film spread and stability has been successfully developed.
- This simple measurement technique shows potential for differentiating the performance of various soft contact lens materials.
- Further research is warranted to explore the utility of this method in assessing non-invasive tear breakup time, surface deposition, and overall lens comfort.
