Research shows tears shed light on presence of eye disease

Your optometrist may make you cry during your next appointment, but don’t worry — it’s for your own good.

Amy Herr, UC Berkeley assistant professor in the Department of Bioengineering, and graduate student Kelly Karns have developed a new method of diagnosing the eye disease Sjogren’s syndrome by analyzing tears. The method uses specially tagged antibodies and an electric current to separate a tear’s proteins to discern whether the syndrome is present.

Tears have so far been difficult to analyze, and data gathered from them is hard to interpret, Karns said. The new method presented in the study, published Sept. 12, decreases analysis time and makes the analytical process more reliable, according to the study, which was a compilation of more than two years of research.

“There’s a big unmet need in ocular diagnostics and technology to measure biochemical components,” said Karns, who came to UC Berkeley in 2008. “A lot of tests right now are reliant on surface staining.”

Current tests are also unreliable, Karns said, and require several hours for processing.

Herr and Karns developed a way of analyzing tears that does not require an immobilized antibody to capture proteins on a surface — the mechanism used by current methods. Instead, the researchers mixed fluorescently tagged antibodies with tears and then placed the mixture into a “hair’s width” of gel, according to Karns. The gel was then exposed to an electric current, which causes the tagged proteins to travel at different rates along the gel, depending on their size. Using a fluorescent microscope, researchers then took pictures of the strips to reveal the protein patterns in the gel.

The whole process, Karns said, takes approximately 20 seconds.

During this study the researchers focused on one particular protein — lactoferrin — which is associated with the Sjogren’s syndrome, an autoimmune disease that destroys mucus-producing cells in the body and causes dry eyes, among other symptoms.

To conduct the study, the researchers obtained tear samples from UC San Francisco that had been gathered from both healthy volunteers and those with the syndrome.

In addition to being much more rapid than traditional tests, the new method also requires less fluid for analysis and is more accurate. Without using such a method, “it’s almost impossible to tell what the dry eyes is caused by. This tool opens up this area of ophthamology,” said Karns.

The current testing method for the syndrome involves a biopsy of a patient’s lip, a procedure that most people would decline, said undergraduate bioengineering student and assistant in the study Aleksandra Denisin.

The researchers plan to conduct further studies to solidify the study’s findings.