Glaucoma 2 eye dr opinions for baseline pressure. One said 27 & other 31. Target 18-19. Treatment result is 18. Which baseline number most accurate?

Both good. 15-20% reduction is the aim. The true target pressure is the one that prevents damage in your eye. It takes time and additional testing to determine if the target pressure is correct. Don't get so caught up in a single number-- both are good.
Depends. Intraocular pressure, iop-normal is between 10-21. This is a rough indicator of the relative pressure in the eye. Elevated pressure can indicate glaucoma, that can cause vision loss. The taret goal to lower pressure depends on many factors including your age, type of glaucoma, the health of your optic nerve, the amount of nerve fiber layer loss, the visual acuity and your visual field changes.