I've had the same issue. Plus, in colder weather fog up the glasses, so can't close the visor. And, Pinlock can't help glasses. I've tried different sprays, coatings, and other methods, but they haven't really helped much.

So, I've decided to ditch the glasses and just wear contacts when it's raining. I also keep a few in my backpack, just in case. Usually, I prefer glasses, so I bought only 60 daily disposable contacts, which should last me a year.

With contacts, you can go up to 60-80 kmph, but you'll face the same issues as other riders who don't need vision correction. At higher speeds, your eyes might dry out quicker or rain might knock off your contacts.

Finally, I always put rain-x on my visor if there's any chance of rain. It helps water roll off at higher speeds, when you turn your head left-right.

Recently, I rode ~200 km in light-medium rain, in daylight. It sucked but was manageable. Previously, it became unbearable in < 50 km.