Dry eye disease

Dry eye disease, also known as keratoconjunctivitis sicca, is a common ophthalmic condition characterized by decreased tear film stability due to abnormal tear quality, quantity, or dynamics, leading to ocular discomfort, damage to the ocular surface, and visual impairment. Normal human eyes require tears to stay clean and healthy. Tears are produced by the lacrimal glands located behind the upper eyelids. With each blink, tears are evenly distributed across the eye surface, keeping it moist. Tears drain into the tear ducts on the inner side of the eyelids and are then expelled. In patients with dry eye disease, the lacrimal glands either fail to produce enough tears or tears evaporate too quickly, leading to symptoms such as eye fatigue, foreign body sensation, and dryness.