Ricin oil is a derived from castor oil (cautionary note: it can be toxic if used orally) and with time, it will reinforce your eyelashes and brows.
 If your eyebrows and lashes are thinning out then consider this solution. In a new mascara tube, add a drop of ricin oil and each day apply with your mascara. If not, use an empty tube and apply with the brush then with a tooth or eyebrow brush dip into a little ricin oil and comb gently by dabbing into the roots of your eyebrows.

This is a long term process, done on a daily basis, you should get a result after a couple of months (this is an average; each of us react differently). You can also use it in your hair to reinforce and encourage growth. Always use organic.