Rav Peretz,

That is quite an interesting question!

I take it you do not mean to receive from us a ruling Halachah l'Ma'aseh, since unfortunately, it is not yet l'Ma'aseh, and the Sanhedrin in the Lishkas ha'Gazis will have to determine such matters when the Mikdash will be rebuilt, speedily in our days (see Mishnah, end of Midos). My personal thoughts on the matter, or those of any Posek, will not be a final Pesak.

That being the case, I assume that you mean something else. You are wondering if I can possibly think of a Heter for a Kohen to serve with his glasses on (so that the Kohanim don't trip over each other all day in the Mikdash).

I would suggest the following. Perhaps the Isur of wearing extra Begadim applies only to items that are in the category of "Begadim," which would not include glasses. What I mean by that is that a Beged is something that passively serves the body, keeping it warm and protecting it from harm. (In addition, a Beged may also have therapeutic properties, such as a Gemi.) Eyeglasses, however, do not serve the body passively. Rather, the wearer uses them actively by constantly peering through them and putting them in the way of the light that reaches its his eyes, to correct his vision. If so it is simply a tool and not a piece of clothing, and it will not constitute Yitur Begadim.

This, of course, does not affect the definition of "Beged" with regard to Shabbos. For Shabbos, anything that is draped around the body in a manner comparative to clothing may be worn on Shabbos. It makes no difference whether or not it is a Beged ; it only makes a difference whether or not it is being worn .

Best wishes,

M. Kornfeld