Can one wear non-prescription sunglasses on shabbas in a place where there is no eruv? Do we say since if the sun gets blocked one might come to take them off in a karm'lis, or do we say it's like regular glasses?
R. Neuwirth in Shemirat Shabbat Kehilchata (16:24) writes that one should not wear ordinary sunglasses in a place where there is no Eruv because they are not considered clothing. However, if the sunglasses are never taken off even indoors (eg. for medical reasons) then they are considered clothing and can be worn even outdoors with no Eruv. In footnote 94 he writes that if the ordinary sunglasses (which would be taken off indoors) are needed for medicinal purposes, there is potentially room for leniency to wear them outdoors with no Eruv if the area is not a Reshut Harabbim Deoraita and the wearer is careful not to take them off even in the shade while outdoors.