I’m a little late to the game on this, but as others mentioned, the fixed focal plane of NVGs makes it extremely difficult if not damn near impossible to use iron sights on a pistol “properly” the way you would during the day with your natural vision, so iron sights, including tritium are indeed “bad” for goggles in that respect.

Part of the issue is that because pistol iron sights tend to be so close to your face, especially when accounting for the length of the goggles, you would need to be at the very extreme edges of close focus for most goggles (and you may actually run out of focus adjustment range on some goggles) to properly focus on the front sight, and the rest of your view would not only just be blurry, but pretty much an unintelligible image, and/or with a lens accessory / aperture, you’d have to constrict it so tightly and lose so much light collection that it would effectively stop being a night vision device.  

I have, however, just messing around, tried it with duals, and it can, in fact work if you’re effectively treating it like an occluded sight (only see the dot / front sight in one eye, and the background in the other), however you need to be 100% spot on with your presentation—more specifically the distance between the front sight and your goggle, as even a small variation in distance / positioning of the pistol may mean the front sight is no longer in focus. It’s kind of fun to try / mess with at the range just to try it, however it’s not something I would really recommend for any kind of serious use or in a dynamic situation, though “night vision bullseye” shooting with iron sights could be an interesting exercise / competition stage.

That being said, if you are concerned about the tritium ”being bad” for your tube or night vision device itself because of the light / brightness, it should not be a concern at all.

Red dots, as others have mentioned, 100% reign supreme when it comes to aiming a pistol under night vision, however, while it is much more difficult and takes some practice / getting used to, prior to RDS being a really common thing on pistols, we and others used to teach utilizing three dot tritium or other luminous sights as a “preferred” method of aiming a pistol with NVGs by lining up the glowing “orbs” in your field of vision (it could probably be done with two dot as well though I’ve never tried it because I’ve never really liked two dot sight formats, day or night—a blacked out rear doesn’t really work as well, except for very close “point shooting” off the front sight-only in which case it at least serves as a muzzle reference point, as you don’t get any kind of alignment reference due to the aforementioned focal distance issues).

Obviously IR lasers are another option, however were “less preferred” mostly due to the lack of good available options, as other than the short lived Crimson Trace IR laser grips, you were mostly limited to LAM / MFAL devices like the X400V, M6/M6X, or even more ridiculous devices like the AN/PEQ-14, which presented some severe duty holster option limitations, which can be a huge concern in terms of effective application as a sidearm / secondary weapon as well as a relatively large muzzle / emitter offset and bloom, which could be an important consideration particularly at extremely close ranges and with low probability shots that require extreme precision with a handgun. The TLR-VIR II does solve both these problems for the most part with the laser emitter “embedded” in the primary illuminator reflector versus underslung on the device housing, however I personally have a little difficulty recommending Streamlights for a “hard duty” application because I’ve seen so many of them fail over the years (though I haven’t seen enough of the TLR-VIR specifically—I’m mostly talking about the TLR II white lights), but I know many people like and use them quite a bit with no issues.

As such, this technique was largely taught just for familiarization and to prove to students it was possible to “use in a pinch,” e.g., for a SWAT cop who had to transition to a secondary while under NODs, and even then, transitioning to white light and aiming with the sights under the goggles would still be preferred in all but the narrowest of circumstances. The practice of truly using pistols effectively and practicing / shooting with them as an effective engagement tool in non-emergency situations did not really become “a thing” until the wide use of RDS, and extreme specialists using pistols as a primary weapon under night vision (e.g., hostage rescue / tubular assault) often had separate and/or highly modified and often unholsterable (or difficult to holster) weapons with full size RDS or LAM / MFALs that they only used in very specific circumstances—the legacy of such practices can be seen in the short-lived ALG / Geissele “Six Second Mount,” however nowadays a good slide mounted pistol red dot can pretty effectively serve both purposes without the need for a separate weapon / configuration for use as both a primary and a secondary / EDC.

~Augee