Latisse is a wonderful product and my patients are thrilled with the results. A very infrequent side effect is pigment change (darkening) of the eyelid skin. I have only seen this in one patient and it should resolve if the product is discontinued. There are no reports of Latisse changing the color of the iris of the eye. When it was used as a Glaucoma medication, it was applied as an eye drop and had a rare side effect of eye color change. Latisse should only be applied to the upper eyelid once daily at bedtime, and you should stop using it if any irritation (another possible side effect) or discoloration develop. If you have Glaucoma, you should check with your eye doctor before using Latisse.