Latisse activates pigment and cell growth -- that is how it works

Latisse activates hair follicles and the pigment within them which is how it works to make lashes longer and darker. This same effect happens to the pigment cells of the iris in rare cases when the medication is placed directly in the eye. This was all learned from Lumigan which is the same Brimatoprost medication but used for glaucoma. It turned out that these patients grew longer lashes as a side effect and that is the basis of using Latisse. The idea with Latisse is not to get any in your eye, or at least not very much, so this should not be much of a worry and there are no reported cases to my knowledge of darkening iris pigment in Latisse patients at this time. To the extent that the medication in other preparations is the same or similar to that in Latisse it would also have the possibility of darkening the iris.