A probe developed for the space program has been found to work as the first non-invasive early detection device for cataracts, the leading cause of vision loss worldwide.

Researchers from the National Eye Institute (NEI), part of the National Institutes of Health, and the National Aeronautics and Space Administration (NASA) collaborated to develop a simple, safe eye test for measuring a protein related to cataract formation. If subtle protein changes can be detected before a cataract develops, people may be able to reduce their cataract risk by making simple lifestyle changes, such as decreasing sun exposure, quitting smoking, stopping certain medications and controlling diabetes.

"By the time the eye's lens appears cloudy from a cataract, it is too late to reverse or medically treat this process," said Manuel B. Datiles III, NEI medical officer and lead author of the clinical study. "This technology can detect the earliest damage to lens proteins, triggering an early warning for cataract formation and blindness."

The new device is based on a laser light technique called dynamic light scattering (DLS). It was initially developed to analyze the growth of protein crystals in a zero-gravity space environment. NASA's Rafat R. Ansari, senior scientist at the John H. Glenn Research Center and co-author of the study, brought the technology's possible clinical applications to the attention of NEI vision researchers when he learned that his father's cataracts were caused by changes in lens proteins.

Several proteins are involved in cataract formation, but one known as alpha-crystallin serves as the eye's own anti-cataract molecule. Alpha-crystallin binds to other proteins when they become damaged, thus preventing them from bunching together to form a cataract.

However, humans are born with a fixed amount of alpha-crystallin, so if the supply becomes depleted due to radiation exposure, smoking, diabetes or other causes, a cataract can result.

"We have shown that this non-invasive technology that was developed for the space program can now be used to look at the early signs of protein damage due to oxidative stress, a key process involved in many medical conditions, including age-related cataract and diabetes, as well as neurodegenerative diseases such as Alzheimer's and Parkinson's," Ansari said. "By understanding the role of protein changes in cataract formation, we can use the lens not just to look at eye disease, but also as a window into the whole body."