Lipid Layer Thickness Changes Following the Instillation of Two Novel Lubricant Eye Drops

Abstract

Abstract: : Purpose: Tear film lipid layer thickness (LLT) has been correlated to the presence of dry eye symptoms. Two novel products, Soothe^TM (Alimera Sciences Inc., Alpharetta, GA) and Systane^TM (Alcon Laboratories, Inc., Fort Worth, TX), have been introduced for the lubrication of dry eye and relief of symptoms. This study was conducted to determine if a single eye drop of either product produced a significant increase in LLT for subjects reporting symptoms indicative of dry eyes. Methods: A double–blind, internally–paired study was performed. A custom lipid layer interferometer, enabling characterization of lipid layer interference patterns, was used to quantify LLT (OU) of eligible subjects. Subjects (n=50) received a single drop of Soothe^TM in one eye and a single drop of Systane^TM in the other eye. Test drops were supplied in masked identical opaque eye dropper bottles. The LLT of all subjects, following the instillation of each test drop, was analyzed. Inclusion criteria included: 1) presence of dry eye symptoms and 2) LLT < 75 nm, with variability no greater than ± 15 nm in each eye or between an individual pair of eyes, over a 15 minute observation period. Results: The mean ± standard error baseline LLT findings pre–eye drop instillation were 61.4 ± 1.6 nm for eyes treated with Soothe^TM, and 60.3 ± 1.7 nm for eyes treated with Systane^TM. These means were not significantly different (p > 0.5). Post–eye drop instillation, the mean LLT for eyes treated with Soothe^TM more than doubled from 61.4 nm to 146.2 ± 4.7 nm, and the mean LLT for eyes treated with Systane^TM increased from 60.3 nm to 83.7 ± 4.8 nm. The mean increase in LLT for Soothe^TM was significantly greater than that produced by the weakest measurable blink response (p < 0.0001). The mean increase in LLT for Systane^TM was not significantly greater than that produced by the weakest measurable blink response (p = 0.07). Conclusions: In subjects with symptoms indicative of dry eye states and with LLT < 75 nm, one eye drop of Soothe^TM resulted in a significant increase in LLT, more than doubling LLT, while the increase for Systane^TM was not significantly greater than that produced by the weakest measurable blink response.

Keywords: cornea: tears/tear film/dry eye • lipids