Dangers of MH lighting to eyes?

[Delphinus]

150W so a double-ended lamp? (There's also a 150W single-ended style lamp).

The double-ended (or "DE") lamps don't have the outer glass globe, which acts as a UV sheild. This is why DE lamps need a cover glass on the pendent whereas single-lamps don't.

Soooo ... long story short, you don't want to make a habit of looking at that light if it's bleeding out the top. I'd consider something like some aluminium-tape (looks like duct tape, and is for furnace vents, but it's like aluminium foil with a sticky backing), and tape up the holes where it's bleeding out.