I have an abnormal optic nerve also. Two optometrist could not figure out what was happening. I went to our states largest and best eye clinic. After several tests they said I was born that way...nothing to worry about. I had a major vision change but he felt it was not related. That's the extent of my knowledge other than structure and function.
So I apologize that I really can't help you. Please know that you are always welcome here...but I am going to request that you post be moved. We have a very informative eye forum. I am sure that someone there will have better answers for you.
I wish you the very best and invite you to stop back to the Senior Health Forum any time. I hope you will find a solutions soon.
The only way to treat a normal tension glaucoma is to lower the IOP.
Even if it is in a normal range.
Maybe the iop is higher at times when it is not measured. For example in the evening or at night.
You should consider taking eye drops as you are having vision loss.
Talk to your eye MD or go find another for a second opinion.
Many people have optic disks that look like possible glaucoma (large cup disk ratio). It happens every day. Visual Field tests have great variability and are sometime unreliable. There are many other factors that have to be considered: your age, your family history, the thickness of your cornea, just how suspicious your c/d ratio is, your refractive error. If you have confidence in your MD it is entirely likely that his/her suggestion is quite appropriate.