The Effect of a New Emulsion in Dry Eye Patients on Tear Layer Aberrometry, Contrast Sensitivity, and Reading Ability

Dry eye patients experience symptoms such as; irritation, dryness, a scratchy sensation, and blur. These symptoms are the result of an insufficient tear layer. Blur can occur in dry eye patients because of an irregular tear film surface. Artificial tears are applied to the eye to treat a variety of eye conditions. These conditions typically are associated with dry eyes and include tear film deficiency due to ocular or systemic disease, lid resurfacing problems, and contact lens wear. The artificial tears are used to alleviate the dry eye symptoms. Dry eye is a frequently encountered ocular condition. Recent studies estimate that 7.8% of women and 4.8% of men over the age of 50 suffer from dry eye. The administration of an artificial tear to the eye can disrupt the tear layer and this disruption could then result in a change in contrast sensitivity for a few moments. Aberrometry is a technique that is able to monitor tear layer disruption and its results may correlate with contrast sensitivity changes. Tear layer disruption results in a decrease in the modulation transfer function (MTF) for the eye. Since the tear layer is the first refracting surface of the eye, its disruption can also result in a change in contrast sensitivity, visual acuity, and aberrometry. Previous work has demonstrated that higher order aberrations increase 1.44 fold after the tear film breaks up in normal subjects. Dry eye subjects demonstrate a significant increase in higher order aberrations (i.e., total S3+4+5, spherical-like S4, and coma-like S3+5) when compared to normal subjects. This has been interpreted to be the result of increased tear irregularities in the dry eye subjects. When an artificial tear (i.e., Vismed) was applied to the tear layer of dry eye subjects, the optical aberrations decreased. This previous study only examined the short term affect (less than 10 minutes) of a single administration of an artificial tear. In this study, we propose to examine the short and long term effects of a new emulsion on contrast sensitivity, optical aberrations, and reading ability after administration into the tear layer of normal and dry eye subjects.