These kits dont cause headaches, Human Wiring does, 3 in 10(random but accurate statistic dont ask me for the source newspapers are fickle) people cant do 3-d without it giving them a whopper headache, you might be one of them. The stat might be wrong but the sentiment isnt , some people just cant do it, no amount of conditioning helps.
For me 15 minutes and i condition just fine, it hurts for a few mins and then i adjust , but it mightnt be that easy.
It wont damage eyesight , contrary to old people nothing damages eye sight but a lovely acid burn.... At worst its just not worth it because the headaches are a btch