Xerophthalmia, as the name suggests, is a medical condition in which the eye feels dry. In fact, it is more than that. Sometimes it has burning sensation, foreign body sensation, and may cause eye fatigue, even itchy, sore and sticky eyes, similar to the symptoms of chronic conjunctivitis. But patients with xerophthalmia often find that the symptoms are more pronounced when they are exposed to a warm environment that accelerates tear evaporation (such as air-conditioned rooms).

Some patients with xerophthalmia may feel they have adequate tears, which is represented by pseudo-epiphora. This may be due to their insufficient basal tear secretion, which stimulates the lacrimal gland to cause reflex tears. In normal blinking, the tear layer in front of the cornea will change, making the eyes feel comfortable and clear, but in xerophthalmia patients, the effect of this change is poor, resulting in discomfort symptoms, and even temporary blurred vision.

How can I have xerophthalmia when I'm still young?

Xerophthalmia, which usually occurs in the elderly, tends to invade younger groups. The reasons for the increasing prevalence of xerophthalmia include the popularity of computer terminals, the popularity of contact lenses and so on. In addition, in an urban concrete jungle, indoor central air conditioning makes the air dry, humidity reduced, tear evaporates quickly, outdoor air pollution serious, which easily leads to eyelid and conjunctiva inflammation.

These can damage our eyes, leading to dry eye symptoms, and such high-risk groups are those who work at the office, among whom most female workers like to wear contact lenses, which aggravates the symptoms of xerophthalmia. It’s no wonder that half of patients with xerophthalmia are in their 30s to 50s, and twice as many women as men!

Xerophthalmia is a medical condition in which the eye fails to produce tears and the eye surface is not evenly moist. The problem with tear production may arise from insufficient secretion, qualitative changes, abnormal blinking and conjunctival or corneal issues. After normal tear secretion, a thin tear film will form before the cornea and conjunctiva of the eyes with blinking. Usually we will not feel its existence, but once the tear film is not working properly, the symptoms arising therefrom may greatly affect your daily life.

The tear film can be divided into three layers: lipid layer, aqueous layer and mucin layer from outside to inside. As long as any of these three layers has problems, it may lead to dry eye symptoms.

The lipid layer is secreted by the tarsal gland (a sebaceous gland) of the eyelid, which can delay the evaporation of the aqueous layer and increase the surface tension of the tear. It is also a lubricant for the eyelid and the contact surface of the eyeball. Therefore, inflammation of eyelids or scarring of eyelid margins, dysfunction of the tarsal gland will affect the function of the lipid layer. These problems are prevalent among young people, especially those who do legwork and often stay up late and have abnormal living habits.

The aqueous layer accounts for most of the tear film, which is secreted by the tears and accessory lacrimal glands. It mainly provides the smooth optical surface of the eye, supplies oxygen to the corneal epithelial cells, and clears the metabolites on the eye surface and acts as a bactericide.

Either congenital or acquired diseases, such as autoimmune diseases, blood diseases, endocrine disorders (e.g. menopause), infections, injuries, surgery, and drugs, will affect the secretion in the aqueous layer.

The mucin layer, secreted by goblet cells in the conjunctiva, turns the corneal epithelium from lipophilic to hydrophilic, allowing the aqueous layer to be evenly distributed across the surface of the cornea.

Any disease that invades conjunctival structure, such as chronic conjunctivitis, trachoma, vitamin A deficiency, chemical (strong acids or bases) burns, will lead to an abnormal mucin layer, which makes the aqueous layer unevenly distributed on the corneal surface, easy to cause dry eye symptoms.

Tearful eyes often cause discomfort as they need to be wiped frequently. On the other hand, these tears can wash away bacteria or toxins accumulated in the conjunctival fornix. Actually, it is prone to corneal and conjunctival epithelium keratinization when there are too few or no tears, which can cause corneal scars and affect vision.

Does frequent tear-shedding cause xerophthalmia?

There are many causes of tears, such as emotional factors, nerve stimulation, ocular surface or retina stimulation, ametropia, allergy, olfactory or endocrine diseases. Tears are mostly caused by reflex secretion. At the early stage of xerophthalmia, the basal tear secretion is insufficient, but stimulating the lacrimal gland causes an increase in reflex secretion, leading to the symptoms of frequent tears. Therefore, frequent tear-shedding does not cause dry eyes, but may be the initial symptoms of xerophthalmia.