Background: There are numerous eye diseases that can lead to blindness. The leading causes of blindness in the world are cataracts and glaucoma. Treatment of glaucoma is conservative and surgical. Cataracts are treated exclusively by surgery. Inflammation of the cornea of the eye, or keratitis, is most often caused by an eye injury or infection. Uveitis or inflammation of the uveal system is caused by eye injury or systemic infection. Keratitis, uveitis and eye injury sometimes require hospitalization for access to treatment. Aim: To determine the most common diagnoses and age groups of patients hospitalized at the ophthalmology department at Dr. Ivo Pedišić General Hospital in Sisak in the period from 2015. to 2021. Methods: The research was conducted as a retrospective analysis of the hospital database on hospitalized patients at the ophthalmology department of the General Hospital in Sisak, in the period from 2015 to 2021. Data on diagnoses, age, gender and duration of hospitalization of the patients were analyzed. Results: The most common diagnosis among hospitalized patients at Dr. Ivo Pedišić General Hospital in Sisak during all analyzed years was senile cataract (78%). The majority of patients who were hospitalized due to senile cataracts were between the ages of 70 and 79 (46.38%). Throughout the analyzed period, 58% of hospitalized female patients with senile cataracts were diagnosed, and 42% of male patients. According to the distribution, with regard to the number of days of hospitalization of patients with senile cataract, most patients spent 1 day in the hospital (45.99%), while the number of patients who spent 2 days was 29.15%. Conclusion: Considering the obtained results, we can conclude that all three hypotheses have been confirmed. Based on the results of the conducted research, we conclude that senile cataract is the most common cause of hospitalization of patients at the ophthalmology department of the General Hospital in Sisak. It would be useful to conduct similar research in other Croatian hospitals and make comparisons about the most common ophthalmological diseases for which patients are hospitalized.