does going for a higher magnification hurt your eyes down the line? I want to get some 3.5 loupes but some students are telling me at my school not to and that they can be bad for your eyes and that it is not worth the price difference. I dont mind paying a few hundred $ extra since this should be only a one time investment (i dont want to buy 2.5 and then 4-5 years later have to buy a new pair that are 3.5 or higher), but if the argument that loupes can hurt your eyes if you get a higher magnification is true then I may reconsider my decision...does anyone have any thoughts on this?