I haven't your problems Steve but ware glasses( god they are a pain with photography) my long sight is not great, You have my sympathies , It's finding a way to workaround these trials Steve, there is always a way it's just tricky at times, . I guess the only help I can give is take you time evaluating an image blow it up big, walk away for a while come back , with" fresh eyes " as it were. go so far completely walk away. don't look at those images for a few days. Fresh eye's even with problems, often mean we evaluate with a little more clarity.. Steve I sort of have to work the other way around I shoot with glasses on but have to remove to check images histogramme etc.. Shooting with glasses on I have terrible problems with condensation early morns, I guess one just tries to live with these things and as Ii say try to workaround them as best one can
Lol nettles awful are they not , nettle proof clothing is utterly essential to me Steve. I tend to shoot scatty things like roe or hares so I ware the full camo rig gloves facemask the lot and also tend to be low, so yes good gear is essential to me the thought of crawling through nettles doesn't worry me at all. I'm possibly a bit of an odd ball Steve, but the importance of good cloths for wildlife can not be overemphasized. Steve if we are comfortable we keep still, if not we fidgit and that is what wildlife sees...... movement!!
All the best mate