preventing the bacteria from forming may not be the problem. if the eye is scratched and the body is trying to repair it drying up the natural fluids in the eye is not going to help with or with out bacteria. if she's worried about bacteria forming she needs to get a prescription from the vets. if she's just trying to nurse the eye to keep it clear and let it heal then boiled water should suffice. the body will take care of the bacteria on it's own whilst flushing the eye. if there is no discharge or redness its unlikely there is a bacterial infection to begin with, boiling the water and letting it cool should be enough to get the bacteria living in the water.


also if it's a fungal infection clearing the bacteria could make it worse.