The eyes are often referred to as the windows to the soul, but they can also reveal much about a person's overall health. Systemic diseases can affect the eyes in numerous ways, causing a variety of ocular manifestations. These manifestations can serve as crucial indicators of underlying medical conditions affecting the entire body. As a result, understanding the ocular manifestations of systemic diseases is essential for healthcare professionals, including ophthalmologists, optometrists, primary care physicians, and other specialists. This knowledge allows for the early diagnosis and management of systemic diseases, which can help prevent or reduce complications and improve patient outcomes. This book aims to provide a comprehensive overview of the ocular manifestations of systemic diseases. It covers a range of systemic diseases, including diabetes, hypertension, autoimmune disorders, infectious diseases, and cancer, among others. Each chapter discusses the epidemiology, pathophysiology, clinical presentation, diagnosis, and management of ocular manifestations associated with a specific systemic disease.