FTW
After having grown vertical for years now and many years of flat before that, I now need glasses and my vision has been ruined.
As vertical growers, you especially are vulnerable to eye damage. I highly suggest turning your HID's off when working in your room/s. If you can't be bothered by that, then get at least 2 pairs of really good sunglasses that can overlap each other.
Metal halides put off UV but HPS don't. If running MH vertically, this will degrade your eyes rapidly. You must wear UV protected sunglasses if working in your room/s with the lights on.
Please listen and learn from my mistakes.
Edit:
Since the creation of this thread, many people have shared their knowledge and experience. A lot of us have purchased Shade 5 welding goggles and it has helped drastically. I still recommend turning your lights off if you need to do some work, but again, if you can't be bothered, goto amazon.com and type in shade 5 (or IR 5) welding goggles. I got the fancy "fly" ones, so it was $13.00 with super saver shipping, but they have a pair that is $7.00.
People spend way more then $7.00 on any other aspect of their grow, invest in yourself.
Just went vertical. Working great so far. I went to Home Depot to get glasses, and they only have big astronaut helmets and masks. I don't order online. Does anyone know of any stores where you can just buy with cash?
Definitely necessary. Peeked in last night, forgot sunglasses, and accidently looked right at the 1k. Awww. Not painful, but it's kind of scary seeing a yellow bar for 5 minutes straight.
Welding supply place should have them. I shut off the light if going in the room, if just peeking in I use normal sunglasses. My plants also block about 50% of the light so with the sunglasses it works fine.