SC430 camber adjustment

[mw430]

The SC430 failed the MOT because of a leaking front shock absorber and, after replacing that, Lexus reported  the nsf tyre was badly worn on the outer edge. The nsf camber is 2.5 degrees and the osf 0.5 degrees so the nsf looks like it's way out!

I see that the camber adjustment can be done with the cam bolt in the lower arm but there's also a vertical bolt, 90109-14009, which is also called a camber adjuster, fitted to the suspension a bit higher up.

It looks like a bolt threaded at both ends so does anyone know what it does and how it's supposed to do it?