In coming decades, doctors might be able to treat or prevent cataracts with eyedrops — all because of an unexpected discovery, revealed during a genetics study, about a molecule that helps make cholesterol in human cells.

Lanosterol, as the substance is known, can reverse the accumulation of proteins in the lens of the eye that appear to cause cataracts, Dr. Kang Zhang and his colleagues at the University of California, San Diego discovered.

The results of the team’s work were published Wednesday in the journal Nature and may hold promise for the tens of millions of people around the world who suffer from cataracts.

Currently, the disease is treatable only through surgical removal of the lens. But potentially, thanks to the lanosterol discovery, patients might someday be able to prevent or treat the disease by using eyedrops or getting an injection.

“It would have a huge public health impact,” said Dr. Robert B. Bhisitkul, a professor of ophthalmology at the UC San Francisco School of Medicine. “Preventing or reversing cataracts with an eyedrop has been the Holy Grail in ophthalmology since the field began.”

Zhang, who is well-known for his research on retinal diseases, had no idea he’d be investigating lanosterol as part of the study.

“It was a surprise,” he said.

The work began as an investigation of the genetics in a single family in which two parents without cataracts, who happened to be first cousins, had four children: three with cataracts and one without.

Sequencing and analyzing the genomes of the parents and the children, Zhang and his team were able to zero in on a likely cause of the diseased kids’ cataracts.