People who see sudden, persistent "floaters" or flashes of light could have a serious eye condition that may lead to blindness if left untreated, say Canadian researchers who looked at how common the conditions are.

Eye specialist Dr. Sanjay Sharma of Queen's University in Kingston, Ont., and his colleagues found that one in seven patients with either floaters or light flashes has a retinal tear that could lead to detachment.

"If we detect a tear and laser it, we can save people from potentially going blind," Sharma, a professor of ophthalmology and epidemiology at Queen's, said in a release.

"But if fluid gets in under the retina and causes it to detach, it may be too late."

Many people see floaters in dim light or while staring at a white surface and they soon disappear harmlessly.

Problems may occur when people experience a sudden onset of dots or cobweb-like floaters that don't go away, or flashes in the eye like fireworks that could mean a retinal tear or detachment, particularly in older people.

Anyone with such symptoms needs to seek immediate medical treatment, Sharma said.

Because retinal tears can be extremely difficult to see, high-tech equipment and a thorough peripheral retinal examination are needed to detect them, he adds.

The study from Queen's is published in this week's issue of the Journal of the American Medical Association.

For the study, researchers analyzed nearly 200 articles published in the peer-reviewed literature. They then performed a meta-analysis of 17 articles, and noted that a retinal tear occurred in 14 per cent of the cases of new-onset floaters associated with an age-related change in the eye's jelly.

With files from The Canadian Press