No you can not use human eye drops on a cat... If there is a problem, take to the vet or go to Petco and buy a eye rinse for cats..
No you should never use human medication on animals unless the vet says so. Besides you don't know if it is the right antibiotic or med to give for certain problems.
No, never under any circumstances do you use human medication on your dog, until you ask your vet and he tells you it's ok and what dosage to give for your dogs weight. You would be doing more harm than good and could end up causing your dog permanent damage and possibly killing your dog.If your dog is having a problem with his eye, then a vet is the only one who can help and treat your dog properly and effectively.