Castor oil is commonly used as condiment, even though some people use it directly to eyes. It's harmless, however, our eyes can't fully absorb it, then other eye problems may caused by the deposits.
Add castor oil in our daily meal can make us healthier by promoting our blood circulation, improving digestive system, and smoothing our skin.
You'd better not to use oil as eye drop, not only for castor oil, but also for the other essential oil.