What Causes Red Blood Vessels in the Eyes?

Many people experience eye disorders in daily life, with the most common manifestation being visible blood vessels (redness) in the sclera (white of the eye). In a healthy eye, the sclera appears uniformly white and free of discoloration or foreign substances. So, what causes red blood vessels in the eyes? Below is an explanation.

What Causes Red Blood Vessels in the Eyes?

1. Climate and Environmental Factors

Prolonged residence in harsh environments—such as high-altitude regions with thin air—can lead to tissue hypoxia, triggering compensatory increases in red blood cell count and vasodilation. Over time, this may impair vascular contractile function, resulting in persistent conjunctival vessel dilation (visible red blood vessels).

2. Improper Use of Cosmetics

Many women regularly use cosmetics. During application, fine powders or particles may inadvertently enter the eyes, potentially causing irritation or infection. Individuals who wear false eyelashes, apply eyeliner, or use colored contact lenses are especially susceptible to ocular irritation that may induce conjunctival redness.

3. Eye Strain

Excessive visual tasks—such as prolonged computer or smartphone use—without adequate breaks can cause significant eye fatigue, leading to conjunctival hyperemia (redness). To prevent this, limit screen time, practice regular eye relaxation techniques, and allow overstrained eyes sufficient rest.

4. Excess Liver Fire (Traditional Chinese Medicine Concept)

Prominent conjunctival redness may indicate “excess liver fire,” a concept in Traditional Chinese Medicine (TCM) reflecting a close physiological relationship between the liver and eyes. When liver function declines, stagnation of liver qi or excess liver fire may occur. Symptoms include dryness, discomfort, pain, or burning sensation in the eyes—and notably, diffuse conjunctival redness.

5. Localized Infection

Bacterial or viral invasion of the ocular surface—for example, from rubbing eyes with unwashed hands or exposure to foreign bodies—can trigger localized conjunctival infection, manifesting as redness and blood vessel dilation.

6. Sleep Deprivation

Chronic insufficient sleep deprives the body—including the eyes—of necessary recovery time, leading to ocular fatigue and dryness. This often results in conjunctival congestion and visible red blood vessels. If redness stems from inadequate sleep, restoring a healthy sleep schedule and ensuring sufficient rest is essential for resolution.

The above outlines the primary causes of conjunctival redness. We hope this information proves helpful.