The main cause is vitamin A deficiency. Insufficient intake or excessive consumption of vitamin A can lead to vitamin A deficiency, resulting in a decrease in mucin synthesis by epithelial cells and an increase in keratin, which leads to squamous metaplasia of the mucosal epithelium and glandular epithelium, resulting in the loss or impairment of lacrimal gland cell function. As the disease progresses, the conjunctiva becomes congested and a triangular area of white waxy degeneration is seen near the corneal limbus in the lid fissure, which is known as a Biddle’s patch. The disease can develop in both eyes, but the severity of the disease varies. Children are prone to the disease, and it is often associated with corneal flaccidity, which can have serious consequences. Patients with the disease experience photophobia, dryness, foreign body sensation, night blindness, low or no tears, and vision loss if the cornea is involved.