Comparison of the Efficacy of Two Lipid Emulsion Eyedrops in Increasing Tear Film Lipid Layer Thickness

Abstract

The lipid layer of the tear film is critical to maintaining the thickness of the multilayered tear film. This study was designed to determine whether a single drop of Refresh Dry Eye Therapy or Soothe, both lipid emulsion eyedrops, significantly increased the lipid layer thickness (LLT) of patients with self-reported dry eyes and thin lipid layers. Lipid layer interference patterns were used to quantify the LLT of both eyes of eligible patients before and after test drop instillation. Patients (n=41) reporting dry eye symptoms and having baseline LLT of no more than 75 nm received 40 microL of Refresh Dry Eye Therapy in one eye and 40 microL of Soothe in the contralateral eye. After instillation, LLT was quantified at 1, 5, and 15 minutes. LLT after drop instillation was averaged for the three time points. The mean +/- standard error baseline LLT was 59.6 +/- 1.7 nm for eyes treated with Refresh Dry Eye Therapy and 61.5 +/- 1.6 nm for eyes treated with Soothe. These means were not significantly different (P>0.05). The overall mean LLT after drop instillation was 83.2 +/- 3.6 nm for Refresh Dry Eye Therapy (P<0.0001) and 121.5 +/- 3.8 nm for Soothe (P<0.0001). The mean LLT increase from Soothe (60.0 nm) was significantly greater than that from Refresh Dry Eye Therapy (23.6 nm) (P<0.0001). The application of a lipid emulsion eyedrop will increase LLT and benefit patients with deficient lipid layers who experience dry eye symptoms. Although both products are lipid emulsions, one drop of Soothe essentially doubled LLT and provided a mean increase in LLT that was 2.5 times greater than that of Refresh Dry Eye Therapy.