I don't particularly recommend pointing a blacklight at your eyes for long periods of time. There is some evidence that it can lead to melanoma and snow-blindness, which is essentially a sunburn on your cornea.
Using the technique briefly through the day, such as, just for photographs, or masquerade skits shouldn't do you much harm.
Instead I recommend you use radium eyedrops! ...Wait, no, I forgot, deadly poison radiation sickness...damn.