Just as one may walk in a reshut ha-rabim while wearing clothes because they are deemed secondary to his body, so too one may enter a reshut ha-rabim with other items that serve him, as they too are considered secondary to his body (SA 301:22). For example, one who is hard of hearing may enter a reshut ha-rabim wearing a hearing aid (above 17:3). Similarly, one who is nearsighted may go out wearing glasses, because the glasses are secondary to the body. However, one may not wear sunglasses in a reshut ha-rabim, because there is a concern that when he reaches a shady area he will take them off, put them in his pocket, and carry them. If one needs to wear sunglasses because his eyes are sensitive, and he does not remove them even in the shade, then he may wear them in a reshut ha-rabim. If one has clip-on sunglasses that can simply be flipped up when necessary without being removed from the glasses, he may wear them in a reshut ha-rabim, since there is no concern that one will end up removing and carrying them (see SSK 18:18; Yalkut Yosef 301:35).
If one is wearing an adhesive or cloth bandage to help heal or protect a cut, it is considered serving his body and may be worn in a reshut ha-rabim. Similarly, one with a wounded arm may go out wearing a sling. One whose ear hurts may go out with cotton in it. Bite plates and orthodontic retainers may also be worn. All of these serve the body and are secondary to it (SA 301:28; MB ad loc. 108; SSK 34:29).