Accountants, printers, and green eye shades

I have in fact googled this question, and I only found web pages making use of the references to green eye shades, not explanations of why people wore them.

It seems to have been accountants and printers, and all I can I can think of is that they both spent most of their day staring at figures on paper or little lead blocks. Was the green color supposed to be less taxing on the eyes or something?

A similar question was asked recently: Card dealers and their clear green visors I’ll close this thread and direct further comment to the other one.