Declining eyesight improved by looking at deep red light

I think their device is a LED flashlight with a dark red filter. The visual spectrum is normally around 380-740nm, so their technique stand at right about the edge of out spectrum. Maybe that is why it is ‘exercising’ the eyes.

“Researchers found the 670nm light had no impact in younger individuals, but in those around 40 years and over, significant improvements were obtained.”