FIELD : medicine. SUBSTANCE : group of inventions refers to medicine, namely to ophthalmology, and aims at preventing or treating dry eye syndrome or dry eye symptoms and/or symptoms. Sterile aqueous ophthalmic solution contains from 0.05? to 0.5? (w/w) N-(N-acetylcysteinyl)chitosan or its pharmaceutically acceptable salt in a carrier solution, wherein N-(N-acetylcysteinyl)chitosan has content of free thiol groups in amount of 80 mcmole/g of polymer to 280 mcmole/g of polymer. For preventing or treating dry eye syndrome or dry eye symptoms and/or symptoms, an effective amount of the above sterile aqueous ophthalmic solution is administered into a subject. Another embodiment is a container containing said sterile aqueous ophthalmic solution, wherein the solution is in an atmosphere with oxygen content of 1.5? or less. EFFECT : use of the group of inventions provides an effective, safe, well-tolerated and long-term stability ophthalmic solution, allowing to increase the prevention or treatment of dry eye syndrome or dry eye symptoms and/or symptoms. 18 cl, 10 dwg, 9 tbl, 12 ex