Bottles of eye drops and tubes of eye ointment are generally small because you don’t need much of these medications and having leftover eye medicine is not always a great idea, as the chance of it becoming contaminated is significant.
If the medication label says to use one drop, that is all that is needed. If it’s an ointment, you can use an amount equal to a small grain of rice, advises Shelby Reinstein, DVM, DACVO, on Vet Girl.
If your pet is on multiple topical eye medications, wait at least five minutes between dosing. Otherwise, the first medication may be “washed out” or heavily diluted by the second one. You need to give the medication time to be absorbed. It will be more effective and possibly save you expense and treatment time overall.
While your veterinarian makes the decision on what your cat receives for her eye problem, some cats will show an allergic reaction to eye medications that contain neomycin or polymyxin. Alternatives include erythromycin or tobramycin.
Cats with eye conditions related to herpes virus infections often do best if they receive systemic treatment (oral medications) as well as cleaning and topical treatment for their eye problems.