London, Aug 18 (IANS): Spectacles that are marketed to filter out blue light probably make no difference to eye strain caused by computer use or to sleep quality, according to researchers, including one of Indian-origin.

Blue-light filtering lenses, also known as blue-light blocking spectacles, have been increasingly prescribed or recommended, often by optometrists, since the early 2000s.

Researchers from the UK and Australia reviewed data from 17 randomised controlled trials from six different countries and found no evidence that blue-light filtering lenses protect against damage to the retina, the light-sensitive tissue at the back of the eye.

"The amount of blue light our eyes receive from artificial sources, such as computer screens, is about a thousandth of what we get from natural daylight. It's also worth bearing in mind that blue-light filtering lenses typically filter out about 10-25 per cent of blue light, depending on the specific product," Dr Sumeer Singh, a postdoctoral research fellow at the University of Melbourne,

“Filtering out higher levels of blue light would require the lenses to have an obvious amber tint, which would have a substantial effect on colour perception,” he added.

The potential mechanisms by which blue-light filtering lenses might be able to help with eye strain, sleep and protecting the retina are unclear. One basis for claims about the benefits of these lenses is that modern digital devices such as computers and smart phones emit more blue light than traditional lighting sources, and are being used for longer, and closer to bedtime.

"The outcomes of our review, based on the current, best available evidence, show that the evidence is inconclusive and uncertain for these claims. Our findings do not support the prescription of blue-light filtering lenses to the general population. These results are relevant to a broad range of stakeholders, including eye care professionals, patients, researchers and the broader community," said Laura Downie, Associate Professor at the University of Melbourne.

The review, published in the Cochrane Database of Systematic Reviews, did not find any consistent reports of adverse side effects from using blue-light filtering lenses. Any effects tended to be mild, infrequent and temporary.

They included discomfort wearing the spectacles, headaches and lower mood. These were likely to be related to the wearing of spectacles generally, as similar effects were reported with non-blue-light filtering lenses.

"We found there may be no short-term advantages with using blue-light filtering spectacle lenses to reduce visual fatigue associated with computer use, compared to non-blue-light filtering lenses,” Downie said.

“It is also currently unclear whether these lenses affect vision quality or sleep-related outcomes, and no conclusions could be drawn about any potential effects on retinal health in the longer term. People should be aware of these findings when deciding whether to purchase these spectacles," she added.