If you use the sleeve of a shirt or a handkerchief to clean your glasses, you will probably find that this method did not help you much. And it may have even worsened the whole situation. Not only can you end up with smudges that you cannot see through at all, but if you wore the shirt all day in the field, it can easily happen that you scratch the lenses with dirt that has adhered to the clothing over the course of the day.

Clean more professionally

However, you can also clean your glasses more professionally, i.e., with tools intended for that purpose. The ideal solution is special cleaning wipes or microfiber cloths. The latter are reusable and easy to clean themselves, reducing the chance that you will transfer additional dirt to the glasses.