For the first time, surgeons can “see” cancer cells while performing surgery.

A set of high-tech glasses was used during surgery in St. Louis on Monday that allowed surgeons to distinguish healthy cells from malignant ones. The glasses make the affected cells glow blue to make sure no stray tumor cells get left behind.

“We’re in the early stages of this technology, and more development and testing will be done, but we’re certainly encouraged by the potential benefits to patients,” Dr. Julie Margenthaler, a breast surgeon at Washington University School of Medicine, who performed the operation, said in a statement. “Imagine what it would mean if these glasses eliminated the need for follow-up surgery and the associated pain, inconvenience and anxiety.”

The glasses may help reduce the number of surgeries patients require to remove all cancerous cells. Current standard of care practices involve taking out the tumor and neighboring tissue. Samples are then sent to a pathology lab to determine whether a second surgery is needed to remove more tissue.

Roughly 20 to 25 percent of breast cancer patients need a second surgery since current technology cannot accurately show the extent of the disease during the first operation alone, Margenthaler says.

The glasses, which can detect a tumor as small as 1mm in diameter, were developed by a team led by Samuel Achilefu, Ph.D., professor of radiology and biomedical engineering at Washington University. They were first tested on mice, where researchers used indocyanine green, a commonly used contrast agent approved by the Food and Drug Administration, to distinguish cancer cells under a special light.

The findings, published in the Journal of Biomedical Optics, describe the technique, which includes custom video technology, a head-mounted display and a chemical that attaches to cancer cells and makes them glow when viewed with the glasses.

“A limitation of surgery is that it’s not always clear to the naked eye the distinction between normal tissue and cancerous tissue,” Dr. Ryan Fields, a Washington University assistant professor of surgery, said. “With the glasses developed by Dr. Achilefu, we can better identify the tissue that must be removed.”

Achilefu will seek FDA approval for the molecular agent used to develop the glasses that specifically targets and stays longer in cancer cells.

“This technology has great potential for patients and health care professionals,” Achilefu said. “Our goal is to make sure no cancer is left behind.”