Because tear fluid can be collected quickly and noninvasively, as compared with blood or urine tests for example, it is a valuable diagnostic biofluid. However, only small amounts of it can be collected at a time. Common methods for tear collection are Schirmer strips, a type of paper filter strip placed in the lower lid to absorb tears, and microcapillary tubes yielding only small amounts of fluid, making analysis a long and complicated process. Now researchers have developed a faster, more efficient method that works with small volume samples.
The American Chemical Society recently reported the development of a platform that could enable more efficient and less invasive molecular diagnoses for many diseases and conditions. The new system, called "Incorporated Tear Exosomes Analysis via Rapid-isolation System" (iTEARS) is a modification of a system previously developed to analyze urine and plasma to work with smaller volume tear samples.
Tears are filtered using a nanomembrane less than 100 nanometers thick. In five minutes, the system separates out exosomes, extracellular vesicles that are released from cells. Proteins from the exosomes could be tagged with fluorescent probes while they were still on the device and then transferred to other instruments for further analysis. Nucleic acids, the primary information-carrying molecules in cells, were also extracted from the exosomes and analyzed.
According to a study, "'iTEARS' could help diagnose diseases by isolating biomarkers in tears," ScienceDaily. ScienceDaily, 20 July 2022, the researchers successfully distinguished between healthy controls and patients with various types of dry eye disease based on an assessment of extracted proteins. Similarly, iTEARS enabled researchers to observe differences in microRNAs between patients with diabetic retinopathy and those who didn't have the eye condition, suggesting that the system could help track disease progression. The team says that this work could lead to a more sensitive, faster, and less invasive molecular diagnosis of various diseases using only tears.