What is effect of gentamicin eye drops on kidneys?

Not much: The amount of gentamycin in eye drop is quite small and not likely to have any effect on your kidneys. But likely any medication, use it only if you have to. If you have concerns, consult your doc. Good luck.

Little to none: Though eye drops do get absorbed into the circulation, i can't imagine that a high enough concentration of gentamicin got into your bloodstream to damage your kidneys. If you are concerned, blood testing can assess your kidney function.