There are at least 4 reasons for choosing synthetic prostaglandins as the first-line drugs in glaucoma patients: efficacy, stable 24-hour intraocular pressure control, safety and compliance. Such qualities of these antihypertensive drugs are attracting the attention of ophthalmologists around the world. The use of synthetic prostaglandins is also associated with side effects such as eye irritation. One of the ways to solve this problem is to create a preservative-free form of the drug, free of benzalkonium chloride, including latanoprost. Our 10-week studies have convincingly shown that the use of a preservative-free form of latanoprost (monoprost) allows you to be gentle to the ocular surface, to improve the tolerance of the drug by almost 26.7–37.0 % on the Ocular Surface Disease Index. The use of a preservative-free form of latanoprost (monoprost) in patients with primary open-angle glaucoma increases the hypotensive efficacy of the drug by 9.4–15.4 % in comparison with classical latanoprost.