The human body functions as an interconnected system, with systemic diseases significantly influencing ocular health. Various conditions such as diabetes, hypertension, autoimmune disorders, thyroid diseases, infectious diseases, kidney diseases, blood disorders, and neurological disorders contribute to ocular manifestations, sometimes serving as early indicators of these systemic illnesses. Understanding the relationship between systemic diseases and ocular changes is crucial for early diagnosis and treatment, preventing potential vision loss. This review highlights the mechanisms, clinical manifestations, and modern diagnostic and treatment approaches to systemic diseases affecting eye health. Clinicians must be vigilant in recognizing ocular symptoms to provide comprehensive care, improving patient outcomes.