looks like drs start to suspect glaucoma if cup to disc ratio is above 0.5 - but some people have ratios of 0.8 and no glaucoma
the fact that the ratio appears to be increasing suggests some ongoing process driving it ( unless its the differences in tests / opticians which should not be underestimated )
if it were me i think i would be looking to have more specialists tests done - stereo photos taken etc
some useful resources here
https://www.glaucoma.org/glaucoma/the-optic-nerve-questions-and-answers-from-dr-bradley-schuster.php