This medication is used to treat patients with not enough or inadequate eyelashes. Bimatoprost makes the eyelashes more noticeable by causing more eyelashes to grow and making them longer, thicker, and darker. Bimatoprost is similar to a natural chemical in the body (prostaglandin).Bimatoprost is also used to treat glaucoma. If you are already using or are directed to use bimatoprost to treat glaucoma, be careful not to get this eyelash medication into your eyes. Getting extra bimatoprost in your eyes may make it less effective for treating glaucoma. Talk to your doctor or pharmacist for more details.