Hi, there.
Is it allow to used glasses for visual inspector?
If yes, What’s the acceptance criteria or limit for minus and plus?
There is no cGMP guidance on cleaning validation and glasses. What I do as part of testing operators is putting a known amount of API on a stainless steel plate asking the operators if they can see the residue, swabbing it, and then test the swabs by a chemist by the method of analysis. Failure (~80%) results in the operator not being part of the cleaning validation team.