OK, I may sound a little crazy for this one, but hear me out. Recently, I replaced the high-frequency electronic ballast in the fluorescent light fixture in my bathroom with a traditional line-frequency magnetic ballast. I am very satisfied with the results, however, I’ve noticed a weird effect that occurs to me when I turn the light off abruptly at night.

Occasionally, I have to get up and use the bathroom in the middle of the night, as I’m sure we all do. Usually, when I go in there, I turn on the fluorescent light so that I can see what I’m doing. I experience a bit of eye strain when I first turn on the light, but that’s nothing out of the ordinary. The strange part occurs when I turn the light back off, abruptly going from the magnetic-ballasted line-frequency fluorescent lighting to nearly complete darkness. In the past, with the electronic ballast, everything would look relatively normal to my eyes after enduring this transition. But ever since the magnetic ballast went in, I’ve been noticing that there’s some sort of a “flickering” effect that occurs in my eyes after the light is turned off. It lasts for several seconds but it usually goes away when I close my eyes. Visually, the color of the flicker is white, it sort of looks like increasing and decreasing the opacity of a photograph if that makes sense.

I am really curious as to why this occurs. I am pretty certain it has something to do with the magnetic ballast, since it has only been occurring since that went in. My theory is that my eyes are adjusting to the inherent flicker of that lighting, and then when the lighting is removed, my brain tries to fill in the gaps by producing “flicker” of its own. I don’t think there is any bodily damage caused by this effect, it’s just a strange sensation. Has anyone else experienced a similar thing before? Is it true that the magnetic-ballast fluorescent lighting is the source of it?

I know what you’re talking about. I believe it might not be related to the magnetic ballast like you think. I’ve had it happen to me with incandescent light. I don’t turn on the bathroom light in the middle of the night anymore because I now have a proper night light in there, however.

I think I've seen this with magnetic RS ballasts in the cold.. https://www.lighting-gallery.net/gallery/displayimage.php?pos=-266800

@sol - Interesting. It must just be related to eye strain.

@Emersyn - What I’m referring to is a general “lightening/darkening” effect in the eyes, it doesn’t linger only where the lamps are like that.

So it's only in your vision and not the actual lights like in that video from Emersyn?  I think I've experienced something similal, and here's a post on Reddit.  I've never associated it with any particular form of lighting, but it usually happens after an abrupt shift from brightly lit to pitch dark.  However, what I've had sometimes lasts a few minutes but isn't very pronounced, and does go away once my eyes adjust to the dark.  After that point I'll sometime notice various kinds of "noise" including colored dots and patches that might be some amount of visual snow, phosphenes, or closed-eye visualizations.  I'm not sure I actually have "Visual snow syndrome" however considering it's all this visual noise is minimal when light levels are higher.

On a side note, like @sol I have a nightlight.  I like these which are motion-activated.  It's a good way to be able to use incandescent without wasting power and going through lots of bulbs, and you can simply stick a C7 christmas light in them if you want a different color.

@Patrick - Correct. That Reddit thread sounds somewhat similar to what I’ve been experiencing. I really wasn’t sure if it was the magnetic ballast causing that, and after @sol mentioned getting it with incandescent lighting, I’m now almost certain that it is just a coincidence. I do wonder if it could be the fact that the lighting is now brighter after the magnetic ballast went in though, as the old electronic ballast was only a 0.75 ballast factor while the magnetic is 1.0 of course. Maybe the magnetic ballast pushed things bright enough to cause the flickering sensation. And as I’ve thought about it more, I think it may have occurred a couple of times with the electronic ballast, but it became pretty much every time I left the bathroom in the middle of the night after the magnetic ballast went in. I definitely think it is just eye strain though. These are two F40T12 lamps, so quite a substantial difference between light on and light off.

I do also get those colored patches you refer to as well. I usually get them if I look at a light and shut my eyes. The patch will be the shape of the light and sort of drift around a bit. I also see fainter patches in very very dark conditions (like under my bedcovers) or when I shut my eyes as well. As far as the flickering goes, I have never stayed up long enough for it to disappear (next time I get it, I’ll wait for a little while to see how long it takes) but it goes away immediately when I shut my eyes.

I have tried using nightlights before, but they are just too dim for me.