Is tobramycin ophthalmic solution safe for humans?

Yes, but do not use: It is the other way around. The tobramycin eye drop is fda approved for humans, and is being used for by your vet for your cat. However, just as you should not share antibiotics between family members, you should not use the tobramycin unless it is prescribed to you by your eye md.

May be the same: Many human pharmaceutical eye drops are used in animals. They might be packaged differently, but it appears that the all contain tobramycin 0.3%. I am not totally sure if the veterinary version is exactly the same, as far as preservatives and buffers. It is generally not good to share antibiotic drops because of the risk of spread of infection.

Probably yes: Tobramycin ophthalmic solution 0.3% is a fairly common eye drop, or at least used to be. If it is a veterinary preparation, it should probably not be used in humans. That said, it is probably the same drop. In general, it is not a good idea to self diagnose and treat. Please see an competent eye care professional, and get an evaluation!