Bimatoprost is the active pharmaceutical ingredient found in medications like Lumigan. It is a synthetic prostamide analog that is used to treat certain eye conditions, primarily glaucoma and ocular hypertension, which are characterized by elevated intraocular pressure (pressure within the eye). If left untreated, high intraocular pressure can damage the optic nerve and lead to vision loss. Bimatoprost works by increasing the outflow of aqueous humor (the fluid inside the eye) through the trabecular meshwork, a part of the eye's drainage system. By improving fluid drainage, bimatoprost helps lower intraocular pressure and reduces the risk of further damage to the optic nerve.