Tears are best known as an expression of emotion, both happy and sad, but as a fluid secreted by the body, tears contain specific proteins that can be early indicators, or biomarkers, of systemic disease in other body parts. Researchers have found biomarkers in tears for diabetes, cancer, multiple sclerosis, Alzheimer’s, and Parkinson’s diseases. A study published earlier this year by Multidisciplinary Digital Publishing Institute (MDPI), Tears as the Next Diagnostic Biofluid: A Comparative Study between Ocular Fluid and Blood, compared proteins found in blood plasma with those found in tears.

There it is again, that little speck that glides across my vision from time to time, then disappears. There are times when I’m looking at the sky or a blank wall and notice little shapes floating in front of me. They’re not quite clear — almost like little bits of dust stuck on a camera lens. I try to blink them away, but they’re still there. When I look somewhere else, these shapes move with me. Mostly, it’s an annoyance and distraction, but sometimes it’s briefly entertaining to try to follow their path. But what are they, and where did they come from?