Tear Osmolarity Changes After Instilling Isotonic Hyaluronate Artificial Tears

Background: Osmolarity is defined as the concentration of particles dissolved in a solution. Normal tears contain various dissolved particles including proteins, salts and other electrolytes. The investigators plan to investigate how osmolarity of the tear film changes over time after instillation of artificial tears containing hyaluronate. This is one kind of artificial tear that is used to treat dry eye. Dry eye and tear osmolarity: Dry eye is a significant health problem, but diagnosis and treatment are often ambiguous and ineffective. There has been a resurgence of interest and research in dry eye in the past 5 years, and tear osmolarity has emerged as perhaps, one of the most effective ways to evaluate tear quality and dry eye status. Dry eye is usually treated with artificial tears, and many formulations are available. The investigators will test an isotonic solution that contains hyaluronate. Hyaluronate binds water and should help to maintain water on the eye. Objective: We plan to study the time course of possible changes in tear film osmolarity following instillation of an isotonic artificial tear containing hyaluronate. The investigators will use the TearLab, a new clinical instrument that has been developed to quickly and easily measure tear film osmolarity. Understanding how artificial tears affect tear film osmolarity over time can help doctors determine efficacy and dosing schedules. The investigators will test the isotonic hyaluronate (Blink Contacts) artificial tears relative to normal saline solution. Hypothesis: The investigators should be able to measure a decrease in tear osmolarity over time following instillation due to the water-binding effect of hyaluronate artificial tears relative to a control (normal saline solution).