I just started my first year of university and because I'm visually impared I have trouble seeing what's written on the chalkboard. 
I've partially solved this problem by purchasing chalk from hagoromo and asking my professors to use it. (Leaves a wider and nicer line and erases more cleanly). 

But the chalkboard still gets dirty from chalk which reduces the contrast between the board and the chalk, which in turn makes it harder for me to see.

My university supplies what look to be whiteboard erasers for the blackboard which I suspect isn't a good idea. 

I'm looking for suggestions for premium chalkboard eraser brands or DIY options.

Thanks