Purpose: To apply a commercially available high-resolution spectral domain optical coherence tomographer (SOCT) to assess the change in tear volume after application of a new artificial tears formulation specifically developed for contact lens (CL) users.
Methods: Twenty OD from young healthy CL wearers (mean age, 24.7 ± 3.5 years) with refractive errors ranging from -0.75 to -2.50 D (mean, -1.56 ± 0.69 D) were examined. All subjects were fitted with Focus Dailies CL (Ciba Vision), and two drops of Blink Contacts (AMO), lubricating formulation specifically developed for CL wearers, were instilled after baseline measures. Tear meniscus volume (TMV) was measured immediately after and 1 min, 10, 30, and 60 min after instillation using the Copernicus HR SOCT (Optopol Tech., SA, Poland). TMV was calculated from the local area from tomograms assuming a regular distribution of the tear meniscus across the eyelid. Three scans were taken at each of the time points.
Results: Mean meniscus volume without CL was 1.35 ± 1.18 μL, volume with CL was higher, 1.71 ± 1.56 μL but not significantly different (mean difference, 0.36 ± 1.31 μL). After instillation of Blink Contacts eye drops, meniscus volume increased to an average of 4.10 ± 2.91 μL. Repeated measures analysis of variance showed that values after 10 min were significantly higher than before instillation of eye drops (p < 0.01; mean difference, 0.77 ± 0.65 μL). After 30 and 60 minutes, values of TMV decreased to almost baseline (average mean difference from baseline 0.19 ± 0.18 μL at t30, p < 0.001, and 0.06 ± 0.08 μL at t60, p = 0.004).
Conclusions: High-resolution imaging of the lower tear film meniscus with SOCT systems provides useful measures of tear volume. An artificial tear formulation provides a change in tear volume that is maintained beyond 10 min, although further study, using control groups, would be desirable to determine the consistency of those higher-than-baseline values observed over time.