Sindrom suhog oka (SSO) karakteriziraju razni simptomi i znakovi, a sve češće se povezuje s psihičkim smetnjama. Anksiozna osjetljivost (AO) je osobina povezana s brojnim psihičkim i somatskim zdravstvenim problemima, a od nedavno i sa SSO. Cilj ovog istraživanja je ispitati psihološke čimbenike doživljaja znakova i simptoma SSO kako bi se doprinijelo boljem razumijevanju te bolesti. U laboratorijskom istraživanju 93 osobe su ispunile tri upitnika simptoma suhog oka, Indeks anksiozne osjetljivosti (ASI) i Skale depresije, anksioznosti i stresa (DASS21), te podvrgnute mjerenju znakova SSO. Zatim je u drugom istraživanju online anketom ispitivan odnos između AO, neugodnih emocionalnih stanja i doživljaja simptoma suhog oka. 776 osoba ispunilo je ASI, DASS21 i Indeks bolesti očne površine (OSDI). Testiran je medijacijski model u kojem je kao prediktor uvršten ASI, OSDI kao kriterij i DASS21 kao medijator. Istraživanja su pokazala značajnu povezanost SSO simptoma s AO i ostalim psihičkim varijablama. Drugo istraživanje je potvrdilo medijacijski model i pokazalo da visoka anksiozna osjetljivost izravno utječe na izraženiji doživljaj simptoma suhog oka, i istodobno utječe na osobe da budu sklonije doživljavanju neugodnih emocionalnih stanja što pojačava doživljaj simptoma suhog oka. Rezultati doprinose objašnjenju simptoma SSO kod osoba koje nemaju vidljive znakove bolesti te naglašavaju važnost suradnje stručnjaka očnog i mentalnog zdravlja i psiholoških čimbenika u dijagnostici i liječenju suhog oka.
Introduction: Dry eye disease (DED) is a worldwide public health problem that may cause serious consequences for the patient's health. The etiology of the disease is multifactorial and has not yet been fully explained. The disease has various symptoms, as well as numerous clinical signs. However, both are rarely associated. On the other hand, in recent decades, the number of empirical findings linking this disease to mental disorders, especially anxiety and depressive disorders, has significantly accumulated. Anxiety sensitivity (AS) has so far been confirmed to be associated with numerous psychological and somatic health problems, and recently, its correlation with dry eyes has also been discovered. However, this relationship, as well as the relationship of DED with other psychological variables, has not been entirely investigated. Aim and problems: This dissertation tends to expand the understanding of the dry eye phenomena through the investigation of its psychological determinants, such as anxiety sensitivity (AS). The aim of this research was to examine the psychological factors of experiencing the signs and symptoms of dry eye to contribute to a better understanding of DED. The goal was achieved by examining the correlations between DED signs and symptoms measures, and their correlations with AS and negative emotional states. Next, the influence of AS on the experience of DED symptoms through negative emotional states was examined. Methods: To achieve the aim of the research laboratory and survey research was conducted. To participate in both studies, it was necessary for the person not to be a contact lens wearer, to have no current eye pathology, that have not undergone eye surgery during the last year, and not to use psychopharmacological therapy. In a laboratory study, the correlations between different measures of signs and symptoms of dry eye were examined, as well as their correlations with the measure of AS and of negative emotional states. 93 persons (59.1 % women) of a younger age participated and were tested for dry eye symptoms using three widely used questionnaires. After that, they completed the Anxiety Sensitivity Index (ASI, Peterson & Reiss, 1987) and the Depression, Anxiety, and Stress Scales (DASS21, Lovibond & Lovibond, 1995). Finally, the participants underwent an ophthalmological examination of the DED signs: the tear film breakup time measurement using fluorescein dye and a biomicroscope, non-invasive tear film breakup time, and tear meniscus height measurement using a keratograph with appropriate software. Based on the results, the Ocular Surface Disease Index (OSDI, Allergan Inc., 1995) questionnaire, which proved to be the best of the dry eye symptoms measures was selected for the survey research. The relationship between anxiety sensitivity, negative emotional states, and the experience of dry eye symptoms was further examined in a cross-sectional online survey. 776 persons (62.27 % women) of the general population completed the ASI, DASS21 and OSDI. A simple mediation model was tested using the bootstrap method, in which ASI was included as a predictor, and OSDI as a criterion, while a measure of negative emotional states (DASS21) was included as a mediator. Results: In the first study, no significant association between signs and symptoms of dry eye was established. However, unlike signs, symptoms were significantly associated with psychological variables. Therefore, it only made sense to include measures of dry eye symptoms in the second study. Among them, the OSDI showed the best psychometric properties, as well as the highest association with anxiety sensitivity, and a good association with negative emotional states. Therefore, only this dry eye measure, together with the psychological measures, was used in the survey research on a much larger sample. The survey research confirmed the pattern of association between these measures as obtained in the laboratory study and determined a partial mediation model in which negative emotional states mediate the relationship between anxiety sensitivity and the experience of dry eye symptoms. However, anxiety sensitivity also directly affects the perception of dry eye symptoms. Conclusion: The research has revealed a relatively high prevalence of dry eye in the Croatian population. The first study showed that people who have more expressed dry eye symptoms also have a more expressed anxiety sensitivity and experience more negative emotional states. The second study showed in a large sample that anxiety sensitivity affects the experience of the severity of dry eye symptoms directly and indirectly through the experience of negative emotional states of depression, anxiety, and stress. Highly anxiety-sensitive individuals are more sensitive to dry eye symptoms and will experience them more frequently and intensely. Also, due to high anxiety sensitivity, they will be more inclined to experience negative emotional states, which will then have an additional effect on their more intense dry eye symptoms experience. In a theoretical sense, these results contribute to the understanding of DED regarding its psychological component. Particularly, the results contribute to the possible explanation of DED in a specific group of patients who do not have visible signs of the disease, since they indicate the possible psychological cause of their disease. In a practical sense, the results emphasize the importance of cooperation between eye and mental health professionals and taking psychological factors into account in the DED diagnosis and treatment.