Approved by the FDA in 2000, Unoprostone is an eye drop solution that is used to treat increased eye pressure in patients with glaucoma or ocular (eye) hypertension. It is worth noting that this medication belongs to a group of drugs called prostaglandins, which help to decrease the amount of fluid build-up in the eye. As for the common side effects of Unoprostone, they include burning or stinging upon use, dry eyes, itching, altered vision, eyelid disorder, or a sensation that an object is in the eye. In addition, Unoprostone solution may gradually increase the pigmentation of the iris. On a side note, the long term effects of increased pigmentation are not known. Besides, there are still no adequate and well-controlled studies in pregnant women after using Unoprostone. Therefore, this medication should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.