Conjunctival xerosis (conjunctival dryness) is a phenomenon of conjunctival dryness that occurs mainly as a result of lesions in the conjunctival tissue itself, and has a variety of causes. Under normal conditions, the tear fluid secreted by the lacrimal gland and conjunctival cup cells keeps the conjunctiva constantly moist, but once the above moisturizing function is disrupted, conjunctival xerosis occurs. Conjunctival dryness can be divided into epithelial conjunctival dryness and substantial conjunctival dryness. Clinically, cod liver oil drops are used, along with antibiotic solution and eye ointment to prevent and treat secondary infections, corneal ulcers and corneal softening. Normally the conjunctival surface of the cornea is covered with a layer of oil secreted by the leptomeningeal glands, a layer of aqueous humor secreted by the lacrimal glands, and an innermost layer of mucus secreted by the cup cells. These three layers together form a layer of tear film that protects and moistens the conjunctiva. When the conjunctival epithelial cell layer and subconjunctival tissues are destroyed due to pathology, such as severe trachoma scarring, diphtheritic conjunctivitis, conjunctival aspergillosis, conjunctival chemical or thermal burns, and X-ray irradiation, the lacrimal ducts are blocked by the scarring due to extensive scarring, and paracolic lacrimal glands and conjunctival cup cells are destroyed so that tears and mucus cannot moisturize the eyeball. In addition, incomplete eyelid closure caused by various reasons, so that the conjunctiva and cornea long-term exposure can also occur dryness. The bulbar conjunctiva is dry and loses its luster and elasticity, and its transparency is reduced. When the patient opens his eyes and exposes the conjunctiva for a few seconds, the dryness is more obvious. If a scraping of the bulbar conjunctiva at this time reveals keratinized granules of epithelial cells and a large number of desiccating bacilli, followed by poor conjunctival mobility and elasticity, the bulbar conjunctiva in the lacrimal region appears to be folded parallel to the corneal limbus when the eye is turned. A silver-white foamy triangular spot appears in the conjunctiva on both sides of the corneal limbus in the lacrimal region, with a base toward the corneal limbus and a dry surface that is not moistened by tears, which is known as a dry spot (Bitot’s spot). At the beginning, there are only a few tiny bubbles emanating from the conjunctival surface, which break into flakes of grayish-white color and change from oval to triangular. Conjunctival hyperpigmentation is also an early manifestation of the disease, initially seen in the lower fornix, when turning the lower lid, in the lower fornix of the conjunctiva and the semilunar folds, and finally in the upper fornix can also be seen in light brown pigmentation, after the disease is cured conjunctival dryness first disappeared, but the disappearance of the hyperpigmentation is slower. Early conjunctival cup cells disappear, epithelial cells are vitreous degeneration, sometimes visible pigmentation; later the epithelial cells become flat and thickened, the cell nucleus disappears, and is keratinized. Dry spots contain blepharoplasty secretions, epithelial debris, fat, etc., or dry bacilli. In the early stages, the conjunctival surface is dull, the tissue thickens and tends to keratinize so that it has a dry skin-like appearance and cannot be moistened despite tears. The wrinkled, dry, and keratinized conjunctival epithelium causes unbearable dryness and pain such as photophobia. Along with the changes in the conjunctiva, the cornea is also involved and begins to dry out the epithelial layer, clouding it and leading to decreased or even loss of vision. For eyelid ectropion, eyelid defect, proptosis and make eyelid closure incomplete, can cause localized conjunctival dryness and exposure keratitis. The lid and bulbar conjunctiva in the exposed area are congested, dry, keratinized and thickened.