Zoe' rubbed her little face on everything, the ground the rugs, your pantleg....if you gave her a kiss on her face she would try to rub it off (remember she was a "special" child) doing so caused her to have a lot of bouts of irrated red eyes sometimes. We used sustane eye drops on a regular basis to keep them from becoming infected. If they got infected she got a daily ointment for 10 days to clear it up. We did take her to a visit with the eye specialist to make sure that there was nothing more going on. No glaucoma, no ulcers, no cateracts...just Zoe-ness.
I also use it in their eyes after grooming to get any little hairs washed out.