Repeatability of tear film lipid layer interferometry measurements: A randomized, crossover study

Area of Science:

• Ophthalmology
• Ocular Surface Disease
• Biomedical Optics

Background:

• The tear film's lipid layer is crucial for ocular surface health.
• Accurate measurement of the lipid layer is important for diagnosing and managing dry eye disease.
• Existing methods for assessing the lipid layer include qualitative grading and quantitative thickness measurements.

Purpose of the Study:

• To evaluate the intrasession repeatability and diurnal/day-to-day reproducibility of tear film lipid layer interferometry.
• To compare qualitative grading (Keratograph 5M) and quantitative thickness measurements (LipiView II).
• To assess these measurements in a general community population without pre-existing dry eye or blepharitis.

Main Methods:

• A randomized, crossover study involving 40 healthy community residents.
• Measurements were taken during three sessions: two on the same day (6 hours apart) and one on a separate day.
• Tear film lipid layer grading and thickness were measured three times per session with 10-minute intervals.

Main Results:

• No significant differences were found in lipid layer grading or thickness across all comparisons (p≥0.19).
• High correlations (p<0.001) and good reproducibility (Cohen's κ: 0.670–0.867; ICC: >0.80 for intrasession, 0.60–0.80 for intervisit) were observed.
• Quantitative thickness measurements showed low Bland-Altman biases (around 3 nm) and test-retest repeatability of 4.5–11.7 nm.

Conclusions:

• Both qualitative and quantitative tear film lipid layer interferometry methods demonstrate favorable repeatability and reproducibility.
• These findings support the use of either method in clinical and research settings for reliable lipid layer assessment.
• The study validates these interferometry techniques as dependable tools for evaluating the tear film lipid layer.