Effects of a tear supplement containing hyaluronic acid (HA) on tear film thickness in healthy subjects

Purpose We have recently introduced a new technique for the measurement of tear film thickness (TFT) using ultra-high resolution optical coherence tomography (OCT) in humans. In the present study we hypothesized that the effect of a hyaluronic acid (HA) containing lubricant on TFT can be evaluated using this technique after single instillation. Methods 16 healthy volunteers were included into the present study. The design was randomized, double-masked and placebo controlled. Subjects randomly received in one eye HA-containing eye drops (0.15%, Olixia®, Croma Pharma, Austria) and in the other eye NaCl 0.9%. Measurement of TFT was performed at baseline and thereafter every 10 minutes until 60 minutes after start of instillation. A repeated measures ANOVA model was employed to study statistically significant differences. Results 8 female and 8 male subjects with a mean age of 26.8±4.8 years were included in this study. Baseline TFT was 5.0±0.5 μm in placebo and 4.8±0.5 μm in HA treated eyes. A significant effect of HA containing eyedrops on TFT was seen over time (p=0.014). 10 minutes after instillation TFT increased to 5.5±0.8 μm in the HA containing eyedrops and remained almost stable in the placebo group (5.1±0.8 μm). Post hoc analysis revealed that TFT was increased up to 30 minutes after instillation and then returned to baseline. Conclusion The results of the present study indicate that HA containing eyedrops increase pre-corneal TFT for as long as 30 minutes in healthy subjects. This effect is not seen with NaCl administration. Our data also indicate that measurement of TFT with ultra-high resolution OCT is a promising technique to study residence time of eye drops at the ocular surface.