No, actually, I recommend Tylan 50 injectable all the time for chickens, and it can be given as a sinus flush as well. I just have never used penicllin as an eye drop. I am an RN who has given a lot of different types of penicillin over decades, and we never used it that way. I tend to not recommend things that are not an acceptable method of giving something. I think that your vet may be fine to recommend it, and since you have done it without a problem, it may be safe enough, but I wouldn’t recommend it to someone here. We can disagree to disagree. The OP has a perfectly good eye drop—polysporin, which treats different bacteria and pinkeye, so I think they can go with that.