Effectiveness of Dry Eye Therapy Under Conditions of Environmental Stress

Alan Tomlinson,Louise C Madden,Peter A Simmons

doi:10.3109/02713683.2012.757323

Alan Tomlinson, Louise C Madden + Show 1 more

Open Access

https://doi.org/10.3109/02713683.2012.757323

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Abstract

Purpose: Dry eye is often characterized by increased tear evaporation due to poor tear film quality, especially of the lipid component of the tear film. Using an environmental chamber to induce environmental stress, this study compared the effect of three lubricant eye drops on various aspects of tear physiology in a crossover design (evaporation was the principal outcome measure).Methods: Three eye drop formulas were tested: 0.5% carmellose sodium (Drop C), 0.5% carmellose sodium with added lipid (Drop C-L) and 1.0% glycerine with added lipid (Drop G-L). Nineteen control and 18 dry eye subjects used each product for 2 weeks, three times per day, in a random order, with a minimum 1-week washout between treatment periods. Tear evaporation, break up time, osmolarity, tear structure (by interferometry) and patient symptoms were assessed with the subjects adapted for 10 min in an environmental chamber controlled at 20% relative humidity and 22 °C. The treatment effects were analyzed using general linear model repeated measures analyses of variance.Results: In dry eye subjects, evaporation, break up time, osmolarity and symptoms improved for all formulas (p < 0.05). Normal subjects showed some improvements: evaporation with C-L, osmolarity with C and symptoms with C-L and G-L. Change in evaporation was greater for both C-L and G-L versus C (p < 0.05), and there was a trend for C-L to reduce evaporation more than G-L (p < 0.11). There were no significant treatment effects on tear film structure.Conclusion: Overall, the eye drop formula containing both carmellose sodium and lipid (C-L) produced a greater treatment effect on tear evaporation than the other formulations containing only one of these ingredients. This study also demonstrates the utility of a controlled environmental chamber in showing the difference in performance between dry eye treatments.

Highlights

Dry eye disease, a complex group of conditions, is characterized by a dysfunction of one or more of the components of the tear film, and in 60% or more of patients there is the condition of evaporative dry eye.[1]
Statistical analyses of the effectiveness of treatments with the three formulas for all participants were undertaken by applying a general linear model (GLM) repeated measure analyses of variance (ANOVA) (Table 3 and Figure 2)
Significant differences between the effects of the study treatments were found only for changes in tear evaporation rate; evaporation change was greater with drop formulas were tested: 0.5% carmellose sodium (Drop C)-L compared to Drop C (p50.0001) and with Drop G-L compared to Drop C (p 1⁄4 0.016)

Summary

Introduction

A complex group of conditions, is characterized by a dysfunction of one or more of the components of the tear film, and in 60% or more of patients there is the condition of evaporative dry eye.[1]. Environment chambers work well in this instance, by controlling environmental stress (i.e. lowering RH) and can be used to assess the robustness of therapeutic interventions.[5,8,9,10]. Many dry eye sufferers find symptomatic relief of environmental dry eye symptoms through the use of ocular lubricants.[11,12,13,14,15] There are many ocular therapeutics on the market, with varying compositions. Some formulations contain an oil-in-water emulsion, intended to replenish both aqueous and lipid

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