Dry eye disease occurs when there is an abnormality in both the quantity and quality of tears. It can stem from two main causes: aqueous deficiency and evaporative dry eye. Aqueous deficiency arises when the production of tears is insufficient, leading to a lack of moisture on the ocular surface. On the other hand, evaporative dry eye occurs when there is an inadequate amount of the oily lipid layer in tears, causing rapid evaporation. In many cases, patients experience a combination of both aqueous deficiency and evaporative dry eye, necessitating tailored treatment approaches for optimal relief.