U.S. Food and Drug Administration on Monday approved Merck & Co. Zioptan eye drops to treat glaucoma or ocular hypertension patients who have elevated blood pressure inside the eye.

Tafluprost ophthalmic solution, which works by reducing elevated intraocular pressure (IOP) in the eyes, had already been previously approved for use in certain European countries under the brand name Saflutan. However the FDA had not accepted Merck’s proposed brand name Saflutan for use, thus the name was changed to Zioptan.

The approval of the first preservative-free prostaglandin analog ophthalmic solution was based on five clinical studies of up to two years that involved 905 participants, the drug maker said in a news release.

Preservatives like benzalkonium chloride are commonly used in glaucoma drugs have been linked to some adverse side effects like common allergic reactions and trabeculectomy failure.

The company said that Zioptan reduced intraocular pressure in participants after three to six months of use.

The drugs most common side effects included increase pigmentation of the iris and eyelids, changes in color and thickness of the eyelashes, and redness in the eyes. The company warned that the eye solution should not be used by children or by pregnant women, and nursing women and people with macular swelling or edema should use the product “with caution”.

The New Jersey-based company said that Zioptan is expected to be on pharmacy shelves in March and will cost $97 for a 30-day supply.