[Preservative-containing eye drops and adherence in ophthalmological practice].

Chronic eye diseases, such as glaucoma or dry eye syndrome, require long-term drug application to the eyes. Good adherence is required to achieve the therapeutic goal and patient needs and requirements have to be taken into account. This distinguishes adherence to drug therapy from the former compliance which implies only following medical instructions. Adherence is influenced by socioeconomic, health system-related, disease-related, treatment-related and patient-related factors. It can be measured by tedious procedures, such as electronic monitoring, self-assessment, drop counting and laboratory findings of systemic drug levels. Non-adherence is a growing medical problem worldwide. An increase in adherence means an increased degree of therapeutic safety for the patient and long-term cost savings for the individual as well as society. Non-adherence in chronic diseases, such as glaucoma and dry eye syndrome is increased by eye drops that cause side effects. Often these side effects are caused by agents such as the preservative benzalkonium chloride. To achieve a good adherence preservative-free eye drops are advised.