I cannot find anything in the canon that mentions Tech's goggles, and no not his visor. His goggles/glasses. I believe that it mostly was an aesthetic choice, the colour/tint of the glasses too. So I've decided to make a headcanon:
Tech has a prescription yes, far or near sighted I do not know because I currently do not posses the energy to figure that out. You do it with a comment on this post if you feel up to it.
And because his glasses are not the normal kind and adapted for battle (They have a strap all around his head and don't just sit on his nose), he has the adavantage of not getting them easily knocked off during battles and missions.
But he will still have some of the usual shenanigans for people with glasses:
-pushes the goggles around on his face with the object closest to him, arm, tablet or another clone.
-he needs to clean them but he never does because he's always used to seeing through the dirt.
-forgets his glasses in random places.
-they fog up and he always finds it annoying.
But I also raise you this headcanon:
We all know that his mutation has mostly affected his brain and such. So Tech may have Irlen syndrome which is why his glasses are tinted. The yellowish tint helps him with all the text that he reads on a daily basis and it's extremely helpful when he cannot tint the screen that he is reading on.
He has programmed all of his screens to have a different background and text colour or make it easier for himself. The little genius.
I also headcanon that the other members of the Bad Batch help their little brother by reading things outloud when he cannot read the text himself. Either because of an injury or a headache because of the colour.
