Start by getting rid of all the causes of glare (other, of course, than the idiots coming the other way with un-dipped headlights): Wash both the outside and the inside of your windscreen with vinegar. (Clean your wiper blades with it at the same time).
Once you've done so, check that there's not the slightest hint of 'streaking' when you use your windscreen wipers. (If there is, get the wiper blades changed).
Then examine your specs carefully (assuming that you wear them while driving) to check that they're really clean and, importantly, there aren't loads of tiny scratches on them.
Then book an appointment with your optician to get your sight tested (making sure that you mention that you're particularly concerned about your night vision).
Night driving on country roads is never easy though, especially if you're a bit out of practice.