Dry eye (DE) affects 25-30 million people in the U.S. alone and is responsible for $3.84 billion in direct annual health care costs. Evaporative dry eye (EDE) results from a lipid deficiency in tears causing the premature evaporation of tears. The problem to be solved is that current methods for accurately diagnosing EDE take time and are expensive. A fast, objective, analytical method that can be administered during a routine eye examination (10 minutes) is needed. We propose to address this need using a ultra-fast infrared spectrograph to measure the ratio of lipid to protein in tear fluid sampled with a conventional Schirmer strip;a test routinely administered during an eye exam. The chemical constituents deposited on the Schirmer strip will be measured using a unique measurement approach, which couples separation of the chemical components along the strip and measurement of the distribution of these components with a new, multichannel measurement system employing an attenuated total reflection accessory. The primary cause of EDE is rapid tear evaporation due to low lipid levels. The onset of dry eye conditions can be pre-anticipated by changes in the lipid content of tears (a decrease in lipid to protein ratio (L/P)) measured by an infrared analysis of a tear film obtained on a Schirmer test strip. The long term goal is to provide an instrument compatible with a doctor's office that can rapidly and reliably measure the lipid to protein ratio n tears. This Phase I program will determine the L/P in synthetic and natural tears sampled with a Schirmer strip in less than two minutes with sensitivity (precision) of 1%. The Phase II program will design and construct a bench-top instrument, suitable for use in an ophthalmologist's office. It will use a standard Schirmer strip containing tears extracted from a patient during a routine ophthalmic exam and provide a measure of the lipid to protein ratio. There are more than 18,000 practicing ophthalmologists in the U.S. today. This "user-friendly", technician-operated, PA-IR instrument will allow them to track the L/P ratio for patients and provide for early detectio of the onset of evaporative dry eye (EDE).
The proposed research on the analysis of tears in the course of a routine eye examination will allow the identification of tear components which can be used as a pre-diagnosis of evaporative dry eye disease. This condition, which affects 25-30 million people in the U.S. alone, is responsible for $3.84 billion in direct annual health care costs and an additional $54 billion in indirect costs and lost productivity. This will improve quality of lif, and from an economic point of view, healthcare costs for the public will be reduced.