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The *Huangdi Neijing* (Yellow Emperor's Inner Canon) states: All meridians belong to the eyes; the eyes can see only when they receive nourishment from blood. The *Ling Shu* (Spiritual Pivot, also known as the Needle Classic) states: The essence and qi of the five zang organs and six fu organs all ascend and pour into the eyes, thereby forming the essence of the eyes. The gathering place of this essence is the eyeball; the essence of bone manifests as the black pupil (cornea/pupil area); the essence of blood manifests as the collateral vessels (conjunctival vessels); the essence of qi manifests as the white sclera; and the essence of muscle constitutes the constraints (eyelids). These essences of sinew, bone, blood, and qi, deeply embedded within, combine with the meridians to form the optic nerve system (eye system), which ascends to connect with the brain at the back of the head and emerges from the neck region. Therefore, if pathogenic factors attack the neck region, especially when accompanied by deficiency in the body's healthy qi, the pathogens may penetrate deeply and follow the optic nerve system into the brain. This causes dizziness or rotation of the brain, which then tenses the optic nerve system. Tension in the optic nerve system leads to vertigo and visual spinning. If pathogenic factors attack the eye's essence, and the affected essences fail to coordinate harmoniously, the essence will scatter. Scattered essence results in diplopia (seeing double objects).

The eyes are the repository of the essence of the five zang organs and six fu organs; they are the site where Ying and Wei (nutritive and defensive) qi, Hun and Po (ethereal and corporeal souls) constantly circulate, and they are governed by Shen (spirit). Thus, mental fatigue causes the dispersion of Hun and Po and confusion of will and intention. Consequently, the pupils and black parts of the eyes correspond to Yin, while the whites and red vessels correspond to Yang. The integration of Yin and Yang transmits clarity, enabling sharp vision. The eyes are the messengers of the Heart, and the Heart is the residence of Shen. Therefore, if Shen and Jing (essence) become disordered and fail to function properly, sudden perception of abnormal phenomena causes the dispersion of Jing, Shen, Hun, and Po, leading to a lack of coordination; this state is termed "confusion" (huo).

Li Dongyuan stated: The twelve primary meridians and 365 collaterals all transport their blood and qi upward to the face and through the orifices. Clear yang qi ascends to the eyes to facilitate vision, while turbid qi descends to the ears to facilitate hearing. If mental distress, excessive workload, irregular diet, or overexertion lead to Spleen-Stomach weakness and excessive Heart Fire, the hundred meridians will boil, and blood flow will reverse. Pathogens damaging the orifices result in blindness, obscuring the brightness of the sun and moon.

The essence and qi of the five zang organs and six fu organs are derived from the Spleen and ascend to the eyes. The Spleen is the head of all yin meridians, and the eyes are the patriarch of all blood vessels. Therefore, Spleen deficiency causes the loss of control over the essence of the five zang organs, preventing clear vision. The Heart represents Ministerial Fire (Jun Huo); its spirit should remain calm and tranquil. Dialectical Fire (Xiang Huo) executes its commands; Dialectical Fire refers to the Pericardium, which governs the hundred meridians and nourishes the eyes. However, physical exertion causes erratic movement, and when combined with pathogenic invasion, it damages the blood vessels, giving rise to various diseases. Physicians who fail to regulate the Spleen and Stomach, nourish blood, and calm the spirit, treating only symptoms rather than the root cause, do not understand the correct principles.

Commentary: This discussion comprehensively elucidates the eyes as the patriarch of the zang-fu organs, blood vessels, and essence. It goes far beyond the superficial secular theories limited to the Five Wheels and Eight Corriders.