Dry eye disease (DED) is one of the most common reasons for visiting an ophthalmologist and affects millions of people. It is characterized by chronic inflammation, hyperosmolarity of the tear film and reduced thickness of the lipid layer of the tear film, which causes symptoms such as burning, itching, redness and watering of the eye. The first line of treatment for DED is the use of over-the-counter (OTC) eye drops. For the last few decades, eye drops in the form of nanoemulsions have been researched, and several medicines in this form have been approved for treatment of DED. Oil-in-water (O/W) nanoemulsions provide the possibility of incorporating lipophilic drugs and prolonging their retention time at the site of application. Furthermore, they offer symptomatic treatment without the active substance, thanks to the synergism of the excipients, by stabilizing and replacing of the tear film. They are complex pharmaceutical forms with several physicochemical parameters (such as size, polydispersity index and zeta-potential of the internal phase droplets) which affect their in vivo efficiency. There is great interest in the development of innovative and generic drugs based on nanoemulsion technology, but due to the complexity of nanoemulsions, this development is very challenging. Currently, there are no biorelevant in vitro methods constructed on the basis of key physiological and anatomical aspects of the eye surface, which would enable the effective development of ophthalmic nanoemulsions. The aim of this thesis is to examine the stability of ophthalmic nanoemulsion under the conditions of simulated tear turnover. For this purpose, simple O/W nanoemulsions stabilized by non-ionic surfactant were prepared and the influence of dilution with water or the external phase of the nanoemulsion on the size and polydispersity index and zeta-potential of the nanoemulsion droplets was determined. Then, the stability of a simple nanoemulsion was determined under the conditions of simulated tear turnover using an artificial tear solution containing salts, urea and glucose. During 40 minutes of testing under conditions of continuous biorelevant dilution of the nanoemulsion stabilized with a nonionic surfactant, no significant change in the size, polydispersity index and zeta-potential of the internal phase droplets was observed.