Castor oil has never worked for me. I've been taking fish oil for about three months but it hasn't seemed to have helped much.
Well snap, a few days after starting to put castor oil in my eyes I got conjunctivitis! They had been red and swollen for a few mornings (I'd put them in my eyes before bedtime) and then one morning I couldn't open my eyes has they had gummed together and were a red raw mess! Yep, looked it up and apparently castor oil contains a natural toxin called ricin than can cause conjunctivitis. A few drops of colloidal silver and it went away after a couple of days. Onto another oil methinks!
Castor oil didn't work for my dry eyes. I tried it a few times, with different kinds of Castor Oil bought in health food shops but I woke up with swollen red eyes every time. I didn't use a droper as I didn't have one, I just put it around my eyes and let it run in a bit. But my eyes are better though although I am now living in an incredibly dry apartment (the Swiss give a new meaning to insulation.... ). I follow the advice I saw here of using more grape seed oil in my cooking and occasionally also drink a bit. I now sleep most nights without the use of a cream whether before I would wake up in the middle of the night or in the morning with very gritty eyes.
I also stopped drinking too much water and the sense of dryness in my mouth, especially at night also disappeared. I am not thirsty during the day anymore either. The more I drank the more I seemed to need to drink, not a good thing! And after years of getting up during the night to go to the bathroom although I am now older I hardly ever do that anymore!
I guess that the bottom line is: listen to your body!