סימן פד סעיף ג

מַפְתֵּחַ שֶׁל כֶּסֶף, אַף עַל פִּי שֶׁהוּא נַעֲשֶׂה לְהִשְׁתַּמֵּשׁ בּוֹ, כֵּיוָן שֶׁהוּא גַּם לְתַכְשִׁיט, נוֹהֲגִין לָצֵאת בּוֹ בַּשַׁבָּת, אֲבָל בָּתֵּי עֵינַיִם (מִשְׁקָפַיִם) (ברילל) אַף עַל פִּי שֶׁהֵן מְשֻׁבָּצוֹת בְּכֶסֶף, אָסוּר לָצֵאת בָּהֶן.

A silver key,⁹It serves primarily as jewelry unlike brass and steel keys which are functional and prohibited. even though it is made for ordinary use, since it is also a piece of jewelry, it is customary to carry it on Shabbos.¹⁰As a pin or tie bar. It is better to have a belt using the key as the clasp or tooth of the buckle. The key must also be attached to the end of the belt. But eyeglasses, even if they have silver frames, are forbidden to be carried outside.¹¹This applies both to glasses serving only as an ornament as well as for corrective lenses. Reading glasses are not permitted for you may take them off and carry them. Sunglasses are not permitted unless they are required for a particular eye ailment. [Har Tzvi 173]

תנא דבי אליהו כל השונה הלכות בכל יום מובטח לו שהוא בן העולם הבא שנאמר הליכות עולם לו אל תקרי הליכות אלא הלכות (נדה ע"ג.)