Thanks for that, i don't think it's a vision thing just the volume of light, i had a situation where a car came up behind me and there was so much light i couldn't see in front or to the side of me (don't know whether it was dipped or not). i read somewhere that 90% of drivers were having problems with this. We have a 'wild west' scenario round here where pick ups and quad bikes have lights attached to roll bars and if you get too close to them they turn them on directly into you from behind, very dangerous.
Given how poor coop lights are as standard this isn't great at the best of times.
I'll try the optician route.
I totally agree with this - dipping the RV mirror is much more frequent now but it doesn't stop the dazzling oncomers!
Especially in gas guzzlers whose lights are set higher.