This is just my experience so I don’t know how it applies to you - best to ask your eye doctor to confirm! But for me, I ‘fail’ an eye hospital visual field test in one of my eyes because I have blind spots just in one eye, but the one I did at the optician to confirm I could see well enough to drive was with both eyes at the same time, so that one was completely fine. If you have a condition that affects your visual field, you need to notify the DVLA and they will organise an assessment of your vision for driving. The DVLA website has more info on this.