Comparing Non-Invasive and Fluorescein Tear Break-Up Time in a Pre-Operative Refractive Surgery Population:...

Area of Science:

• Ophthalmology
• Optometry
• Tear Film Dynamics

Background:

• Fluorescein break-up time (FBUT) is a common but potentially biased method for assessing tear film stability.
• Instilling fluorescein can alter tear film dynamics, affecting test validity and repeatability.
• Non-invasive break-up time (NIBUT) offers a less biased alternative for evaluating tear film stability.

Purpose of the Study:

• To compare Fluorescein Break-Up Time (FBUT) and Non-Invasive Break-Up Time (NIBUT) in patients undergoing pre-operative refractive surgery assessment.
• To evaluate the clinical applicability of the conventional 10-second threshold for tear break-up time in both methods.
• To inform pre-operative patient counseling regarding dry eye disease and refractive surgery risks.

Main Methods:

• Analysis of data from consecutive participants attending an ophthalmology clinic for refractive surgery pre-operative assessment.
• Performance of both Non-Invasive Break-Up Time (NIBUT) and Fluorescein Break-Up Time (FBUT) tests.
• Statistical comparisons using Wilcoxon signed-rank and Mann-Whitney U tests, with Spearman's rank correlation for demographic analysis.

Main Results:

• Median NIBUT was 12.5-14.6 seconds, while median FBUT was 6-7 seconds for both eyes.
• A statistically significant difference (p < 0.001) was observed between NIBUT and FBUT measurements.
• FBUT values were consistently lower than NIBUT values, indicating underestimation of tear stability.

Conclusions:

• The standard 10-second threshold for tear break-up time is not uniformly applicable to both FBUT and NIBUT.
• FBUT systematically underestimates tear film stability compared to NIBUT.
• Accurate assessment of tear film stability using appropriate methods is crucial for pre-operative refractive surgery evaluations.