Z990 --Looking for an external flash that will sync optically

I am trying to find an external flash that will sync optically with my Kodak Z990. Meaning, I know there are flashes that have an eye on them that "look" for a flash from some other source and that triggers them.  Is there a commercially available flash unit that will work with my Z990?

I tried to use a studio flash my pro friend lent to me, but the sync must have been off because every picture came out black. Hard to understand this, as the Z990 seemed to be closing the shutter before it's own flash even went off.

But that's not for this thread. I would want an external flash that can be adjusted in milli seconds, I guess, so I can get it to sync exactly with my Kodak.

Can anyone help me?