So we all have natural rhythm so that we know when we get tired, when it's time to go to bed. ROSENFIELD: The only thing they may be good for is that studies have shown the blue light can interfere with our bodies' light cycle. GARCIA-NAVARRO: So these glasses - are they good for anything at all? And also people tend to look at these screens for very long periods of time without taking breaks. We found that people were holding them sometimes as close as 8, 9 inches away, whereas printed material is typically held around 16 inches away. They tend to hold them at pretty close distances, especially smartphones. ROSENFIELD: We think - it's not so much the screens themselves but rather the way people use them. GARCIA-NAVARRO: So what is the cause of digital eye strain? And again, we found exactly the same effect - that the blue-blocking filters produced no significant change in symptoms of digital eye strain. And the experimenter also didn't know which lens that the subjects were looking through. But this time, we used commercially available spectacle lenses that typically only block around 20 to 25% of the blue.Īnd the second study was done on a double-blind basis, which meant that the subjects didn't know whether they were looking through the blue-blocking filters or just a clear lens. Now, because that filter blocked almost 100% of the blue light, and very few commercially available lenses actually do that, we redid the study. And we found no significant difference in symptoms, whether they were using the blue-blocking filter or they were just using a tinted lens, in effect. And we had the subjects read from a tablet computer for about 30 minutes. The first study, we used the filter that blocked almost 100% of the blue light. I mean, how did you prove that in your study? It always feels like these things might just be sort of gimmicks. GARCIA-NAVARRO: I have to say that feels like a big reveal, but I'm not surprised. This didn't really come as a major surprise to us because there really is no mechanism whereby the blue light should be causing digital eye strain. ROSENFIELD: Both of the studies actually found that the blue-blocking filters have no effect, no significant effect on digital eye strain. GARCIA-NAVARRO: So what did your study discover about wearing these glasses? He conducted two studies on the effectiveness of blue light-blocking glasses on digital eye strain, and he joins us now. Mark Rosenfield is a professor at the College of Optometry at State University of New York. Sales have more than doubled during the pandemic, but are they worth the cost? Dr. So some have turned to blue light-blocking glasses. And this has resulted in what's known as digital eye strain, tired and dry eyes from so much screen time. Kids are schooling at home, clicking on computers rather than raising their hands in classrooms.

Many of us, of course, are working from home. Screen time has gone up during the pandemic.

Blue light blocking screen for laptop