That's because you've had the light very close for 15 minutes. It's very bright. Don't open your eyes while you use the mask. When I take the mask off I see the green glow briefly (a couple of seconds) and then it goes away.
That is not good. Did you follow instructions, which are to CLOSE your eyes, to COVER your eyes with the internal cups like glasses, and to have the light ON while doing the treatment? If this happens at all ever again, or any vision abnormalities, return the product and TELL them why, and report it to the manufacturer and FDA number in the paperwork.
The eyes react to the red light, if you where looking into blue light for a while then the bedroom light would be very yellow .. natural effect.. your brain where the colors are produced and not inside your eyes and after you remove the mask it is like an color negative memory , the brain need to adjust itself back.. nothing to worry about, it is total normal , the inversion of red is green , and ,for green red, and for blue , yellow and for yellow blue ..and all you see is inverted color memory for a little while that go away when the brain adjust it again to normal. so don't worry
That is just from having your eyes closed in the dark. That can even happen while lying in the sun outside with sunglasses on. I always close my eyes and sometimes may see a little green. Nothing to worry about though.
I've never had that problem with this. I do not normally leave my eye open when I use it. I put on some music and just relax for the 15 minutes. I've never tried it in the dark maybe turn a light on?