Try putting a small piece of orange streamer tape on your glasses so you can save that 30s next time. As we get older we all want to save time anyplace we can.
Yeah, done that before, just been a long time and forgot.
The 30 seconds didn't bother me. Was just hoping I'd find them. The ground cover was all oak leaves and glasses can easily vanish.
A branch flicked my glasses off three-fourths of the way around a middle course at the public meet in conjunction with the Estonia world champs 3 years ago. Would otherwise surely have been my best run of the week. Spent a full 10 minutes looking for them, unsuccessfully; thin brown wire frame, which as you say, vanish in the leaves. Took careful note of where I was from a nearby dirt road, then finished the rest of the course without too much trouble (like many myopics, my vision has gotten less bad with age).
Walked back out with Betsy, who found them within seconds. Put them on, but something wasn't right, vision all screwed up. Oh: one lens is missing. Betsy to the rescue again, almost as quick as with the frame. A clear lens is even more difficult to see among the leaves than the frame, but the sun was out and she happened to catch a glint.
Betsy and I were both rough on our glasses that trip, we made three or four visits to Estonian and Finnish opticians.
Rick and Linda were there and he suggested the streamer thing. I've been diligently doing it since.
An optician can also adjust your glasses so that they hold on better. I'm pretty sure I've never had my glasses come off while orienteering. I cannot make them come off with head motion.