If you are continuing to experience deterioration of your optic nerve in spite of having low eye pressure (such as normal tension glaucoma - also called low tension glaucoma), you may find this information very interesting. In fact, I think all glaucoma patients who have any progressing optic nerve damage should have their eye pressure monitored during the night (ideally while they sleep at home in familiar surroundings).
I just monitored my eye pressure for 24 hours. I took 111 intraocular pressure measurements during this period. Over 30 of those measurements were taken in the supine position. The results are a bit surprising.
Throughout the day, my eye pressure was always under 14. The high was actually 13.7. My average eye pressure was 11.9 during this period - prior to going to bed. This is consistent with the thousands of measurements I've done over the last month. However, while I was sleeping last night, my eye pressure reached 25! I find this very surprising because my eye pressure seems so well controlled now.
If you had your eye pressure checked many, many times under different situations and at different times of the day and it was always below 14, I bet you would be surprised if it went as high as 25 while you slept!
Here is a chart showing the 24 hour monitoring of my eye pressure. Click the link for a full size chart. (Note that the x-axis time scale is not proportional. Some measurements are taken a short time apart and others are taken hours apart.)
The light blue shaded area shows my eye pressure while I was lying down reading. The light green shaded area shows my eye pressure while I was sleeping. The measurements in these 2 shaded areas were all taken in the supine position. The area in between these two shaded regions show the effect of a postural change. I went from lying to standing and my IOP briefly jumped up to 19 before it came back down to 13 (within less than a minute).
You might be able to discern information like this with a hospital-based 24 hour eye pressure monitoring program, but since I feel strongly that stress affects eye pressure, I would recommend that you find a way to monitor your intraocular pressure at home in order to find out what is really happening in your eyes. If you have any kind of continuing optic nerve damage, it is worth checking this.