What are the main causes of dry eye?

Dry eye is a condition that occurs when the eye does not produce enough tears, or when the tears are of poor quality and cannot keep the surface of the eye consistently moist [1]. Tears play a pivotal role in protecting and cleaning the eye with every blink, and are essential for maintaining clear and comfortable vision [1]. To understand why some people develop this condition, one must look at the complex balance of the eye's tear system.

How a tear system dysfunction affects the eye

Lacrimal glands produce tears that travel through tiny ducts to reach the surface of the eye, providing continuous hydration and protection [1]. When this system is disrupted, whether due to low production or rapid tear evaporation, symptoms of dryness appear [1]. To learn more about how this system works and what happens when the ducts are obstructed, you can view Tear problems: from dry eye to blocked tear ducts (Arabic).

Environmental and lifestyle factors

Our surrounding conditions play a major role in how quickly tears evaporate and the severity of dryness. These factors include:

• Continuous exposure to dry air, strong winds, or smoke, which increases tear evaporation from the eye surface.
• Intensive use of screens and digital devices, as intense focus reduces the blink rate, preventing tears from being evenly distributed.
• Aging, which is often associated with a natural decline in the efficiency of the glands responsible for tear production.

Medical and physiological causes

Dry eye can be a symptom of an underlying medical condition that requires specialized attention. Some known conditions include:

• Systemic diseases: Certain conditions like Sjögren's syndrome are directly linked to dry eye, in addition to other diseases that may affect tissues surrounding the eye [1].
• Side effects of medications: Some treatments, including antihistamines, decongestants, and certain psychiatric medications, can reduce tear secretion.
• Eyelid problems: Any inflammation or dysfunction in the eyelids can hinder proper tear distribution or affect their quality, leading to dryness of the eye's front surface.

When to see a doctor

If you experience persistent pain, burning, or a foreign body sensation in the eye that does not resolve with simple hydration, there may be a medical cause that requires diagnosis [1]. You should also be attentive if there is severe redness, abnormal discharge, or changes in vision, as these signs may indicate an infection or a problem with the tear drainage system, such as a blocked tear duct, which requires careful assessment by an ophthalmologist [1], [3]. Do not rely on self-treatment alone if symptoms persist; an accurate diagnosis is the first step in determining the appropriate treatment to ensure long-term protection of the eye surface [3].

Medical references

• Tears
• Blocked tear duct