No clue what's needed for treat this in terms of dosage etc.
But I've put a concentration of 6 drops P/1/2 cup of water in my eyes in an effort to treat Pink Eye without any side effects whatsoever(no burning etc).

I also soaked my eyes in the same concentration in an effort to subdue itching and redness.

Other than that, I would think that a parasitic treatment would likely take place internally rather than externally.
But I could be completely wrong about that.

Hope this helps