SCP Foundation

The SCP is a phoropter (Those things they use to test your eyesight at an eye exam clinic). I need some ideas for what it's anomalies are. The backstory is that it was found untouched in an abandoned Optometry Clinic. (Maybe the origin can be changed to fit the anomaly?)

And I really don't want it to be something like "oh yea it makes you blind" or something like that as it feels like a pretty cliche thing to do with it.

Idea:
I was thinking that maybe there is a second dimension on the other side of the device(As in on the other side of the view part of it looking through) This dimension is the exact same as the normal, world, except with less color. Dialing the knobs on the device will alter the dimension looking through. There is a button on the device that will send the viewer to send dimension. After which, there is no way of getting out. The viewer sees many people who accidentally went into the dimension while looking through. They see them begging for help.
The Foundation found notes from the previous doctor who worked with the device, talking about all his wonderful patients and how he wishes they were his children. (or some other spooky plot)

This might not be the best idea, but thats what i'm here for.

So I used to work at an eye clinic for a few months to help out a family friend. The piece of equipment I remember the most was the Autorefractor, which was that kinda stubby white thing that looked like a microscope. When you looked through and it focused, you would see a little farmhouse as a test.

Maybe have it incorporate something like that? I'd be concerned about trying too hard to make it spooky, but I see a lot of potential for weird. Maybe the viewer sees people living in the farmhouse, living their lives, until over the next few viewings things go bad and they witness these changes?