For whatever reason, Julbo glacier glasses don't fit me well at all, I get a big gap below each eye which lets in way too much light. So the money I spent on custom Julbos was essentially wasted. And alternatives to Julbo where you can order prescription lenses are hard to find. I recently discovered another option while getting my annual eye checkup. The optometrist showed me some sport sunglasses by Liberty Sport with an eye protection option called "MagTraxion" which is a removable padded ventilated soft flexible insert. It fills in a lot of the space around each lens and really blocks the light. And they were able to order the prescription lenses with a wide variety of options including percentage of light transmission. So I specified light transmission of between 8 and 10 % max. Just picked them up today, they fit really well and are super comfortable. I got the TrailBlazer 1 model. They come with a nice case and an adjustable cord which attaches to the ends of the "temples" in a really simple positive way, by snapping a small plastic post through a hole in the end of each temple. The only negative was that I could not specify the permanent anti-fog coating option together with the custom dark tinting to reduce light transmission to the level of glacier glasses. But they bundled a little plastic container of anti-fog lens cleaner that can be applied with a cloth. Looking forward to trying these out on Mt Shasta in a week or so.

The curse of the cheek gap. I know this well.