bubble_chart Overview

Conjunctival xerosis is a phenomenon primarily caused by pathological changes in the conjunctival tissue itself, with various underlying reasons. Conjunctival xerosis can be divided into two types: 1. Epithelial conjunctival xerosis; 2. Parenchymal conjunctival xerosis.

bubble_chart Etiology

This condition is a systemic nutritional disorder and an ocular manifestation of vitamin A deficiency. The causes include the following aspects:

1. Inadequate intake: Such as improper feeding in infants or insufficient intake due to "dietary restrictions" during illness.

2. Malabsorption: Conditions like indigestion, gastroenteritis, dysentery, etc., can impair the absorption of vitamin A. Conversely, vitamin A deficiency can lead to pathological changes in the intestinal epithelium, creating a vicious cycle.

3. Excessive consumption: During early childhood, rapid physical growth and development increase the demand for vitamin A. Diseases such as measles, pneumonia, whooping cough, etc., further elevate the consumption of vitamin A. How did you get here? Hello!

4. Adult vitamin A deficiency: Occasionally seen in long-term severe gastrointestinal digestive disorders, malabsorption of vitamin A, or liver and lung diseases such as cirrhosis and liver cancer advanced stage. Severe liver dysfunction leads to fat malabsorption, resulting in a deficiency of fat-soluble vitamin A.

Under normal conditions, the conjunctival and corneal surfaces are covered by an oily layer secreted by the meibomian glands, beneath which lies an aqueous layer secreted by the lacrimal glands, and the innermost layer consists of a mucous layer secreted by goblet cells. These three layers together form the tear film, which protects and moistens the conjunctiva. When the conjunctival epithelial layer and subconjunctival tissues are damaged by pathological conditions—such as severe prickly-ash-like sore (trachoma) scars, diphtheritic conjunctivitis, conjunctival pemphigus, chemical or thermal burns of the conjunctiva, or post-X-ray irradiation—extensive scar formation can block the lacrimal ducts, destroy the accessory lacrimal glands and conjunctival goblet cells, preventing tears and mucus from adequately moistening the eyeball. Additionally, incomplete eyelid closure due to various causes can lead to prolonged exposure of the conjunctiva and cornea, resulting in dryness.

bubble_chart Clinical Manifestations

The bulbar conjunctiva becomes dry, loses its luster and elasticity, and its transparency decreases. When the patient keeps their eyes open and exposes the conjunctiva for a few seconds, the dryness becomes more pronounced. If a scraping is taken from the bulbar conjunctiva at this time, keratinized granules of epithelial cells and a large number of dry bacilli can be found. Subsequently, the conjunctiva's mobility and elasticity are reduced, and when the eyeball moves, folds parallel to the corneal limbus appear in the bulbar conjunctiva of the palpebral fissure. On both sides of the corneal limbus in the palpebral fissure, silver-white foamy triangular patches appear on the bulbar conjunctiva, with their base toward the corneal limbus. These patches are dry and not moistened by tears, known as Bitot's spots. Initially, only a few tiny foam-like spots are scattered on the conjunctival surface, which later coalesce into grayish-white patches, changing from oval to triangular. Conjunctival pigmentation is also an early manifestation of this condition, first appearing in the lower fornix. When the lower eyelid is everted, pigmentation can be seen in the conjunctiva of the lower fornix and the semilunar fold, and eventually, light brown pigmentation may also appear in the upper fornix. After recovery, conjunctival dryness disappears first, but pigmentation fades more slowly.

In the early stages, conjunctival goblet cells disappear, and epithelial cells undergo hyaline degeneration, sometimes with visible pigmentation. Later, epithelial cells flatten and thicken, nuclei disappear, and keratinization occurs. Bitot's spots contain secretions from the meibomian glands, epithelial debris, fat, and sometimes dry bacilli.

Early on, the conjunctival surface appears dull and thickened, tending toward keratinization, giving it a dry, skin-like appearance that cannot be moistened even by tears. The wrinkled, dry, and keratinized conjunctival epithelium causes unbearable dryness and photophobia. While the conjunctiva undergoes these changes, the cornea is also affected, initially with dryness and opacity of the epithelial layer, leading to decreased vision or even blindness.

Conditions such as ectropion, eyelid defects, or exophthalmos that prevent complete eyelid closure can cause localized conjunctival dryness and exposure keratitis. The exposed areas of the palpebral and bulbar conjunctiva become congested, dry, keratinized, and thickened.

bubble_chart Treatment Measures

1. Local treatment: Apply cod liver oil eye drops, along with antibiotic solutions and ointments, to prevent and treat secondary infections, corneal ulcers, and corneal softening. Atropine should also be used to dilate the pupils, along with antibiotic ointments.

2. Systemic treatment: The primary focus is to improve the patient's nutritional status and prevent secondary infections. Consume foods rich in vitamin A, such as milk, eggs, pork liver, and carotene-rich vegetables; take cod liver oil orally. For patients with indigestion or gastrointestinal disorders, intramuscular injections of vitamin A or AD can be administered once daily. Systemic complications should be addressed through active collaborative treatment with pediatric or internal medicine departments.

Currently, there is no effective treatment, and management is mainly symptomatic. To alleviate discomfort, frequent instillation of saline solution, artificial tears, or antibiotic ointments can be used. Alternatively, small lacrimal puncta can be sealed by electrocautery to reduce tear drainage. Some patients undergo parotid duct transplantation, which may provide some symptomatic relief, though excessive parotid secretion during meals can lead to persistent tearing. In recent years, hydrophilic soft corneal contact lenses have been used, though their efficacy remains uncertain. For dry eyes caused by incomplete eyelid closure, eyelid reconstruction surgery may be performed. Once incomplete eyelid closure is corrected, the conjunctiva may recover to some extent.