boric acid in eyedrops

Not long ago I was looking at over-the-counter eyedrops at the drug store, and I was surprised to find that Visine and other similar products contain boric acid. Having previously encountered boric acid only as a white powder that kills cockroaches like nothing else, I decided that I might not want to be putting the stuff in my eyes. Anyone out there got a good explanation for why boric acid is in common eyedrops? Would it be harmful if used frequently?

Boric acid is recommended first aid for washing out your eyes. It must be similar to eye fluids.

The Merck Index doesn’t list “eye drops” as a common use of boric acid, but it does say that it’s an antiseptic; my guess is that that’s the reason it’s in there.

As for being a cockroach poison… sure, but consider how much you put out for them, and how big they are compared to you. Toxic human doses are from “less than 5 grams” for infants up to “5 to 20 grams” for adults (again from the Merck).