In epsisode 466, Conan sees something down in a lake and Agasa says:
Use the magnifying function of your glasses
Allowing Conan to zoom in and see the body floating.
I don't recall this functionality ever being mentioned before. The way he mentions it and the way Conan responds makes it seem like it is obvious they both knew about it at this point. When did Professor Agasa add this feature to Conan's glasses?