The spinal tap IS the test. They use a spinal tap in order to measure the pressure. The one I was given was administered incorrectly. The very severe pain I had that was increasing over six months time completely went away within about 5 minutes after the spinal tap.

The fact that you brought up the optic nerve is especially interesting to me because on one of the many trips I had to take to the ER during this tortuous 6 month time period, I was specifically experiencing severe pain behind one of my eyes and when I told my neuro about it, that's what made her want to order the spinal tap to measure the pressure.

Tell your neuro all these symptoms you are experiencing. Ask them straight up whether a spinal tap would be worth while for you.

Of course, I'm not a medical professional and it could be lots and lots of things (maybe) so just make sure you tell your neuro all this stuff to help them figure it out.