I've got sensitive eyes and most of the time when outdoors, even if overcast, I have to wear sunglasses. On bright mornings when commuting even a combo of cat.3 glasses and the VPS visor in my Nolan helmet may not be enough for me. To give you an idea how bad things are, at one point I owned a pair of Julbo cat. 4 mountaineering glasses (the ones that warn you not to wear them for driving) and I still needed to lower the VPS visor when riding into the low sun. So one of the problems is this riding directly into the sun, which is so painful that no amount of glasses and visors can save me and even if they do I end up not seeing the traffic around me.
I thought adding an opaque visor at an angle to the helmed (like a baseball hat) could help on many occasions -- because the problem is only the upper part of the field of vision. I wondered why so few motorcycle helmets have these visors (only moto-X seem to have from my enquiry) or even are easily amenable. I ordered the "Super-Visor" stateside, got a new Nolan faceshield and carefully followed instructions on sanding the areas on top of the faceshield and attaching the Super-Visor to it with the glue provided. It only lasted a couple of days though, (it was a definite improvement in blocking sunlight and glare). After that the visor detached itself. I think this is because the difference in the natural curve of the faceshield and the visor created pressure at the mount points that gradually overcame the gluing force. See the photos if curious.

The other problem is the fogging. I was blessed in previous years with very good Bolle Swisher sunglasses that did not fog up at all, even with the faceshield closed. These are long out of production so not sold even on ebay now. I had to start using other sunglasses and I have not yet found a pair that would be immune to fogging. That Julbo cat.4 and another Julbo pair with Cameleon lens claimed to have antifog coating, but alas, they do fog up unless I crack the faceshield open. All other glasses (and I am a freak going through 6 pairs a year) are even worse -- I had three motorcycling sunglasses from Hein Gericke, all fogged up like crazy. The new Bolle stuff is also no good. I am a bit despaired because on extremely cold or wet days it's not very comfortable to ride with the faceshield up all the time.
Anyone knows a brand that is fully fog-proof? Anyone heard of Revo stuff? Any other ideas about add-on visors? Any ideas appreciated.