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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 nourished by blood. The *Zhenjing* (Classic of Acupuncture) states: The essence and qi of the five zang organs and six fu organs all ascend and pour into the eyes, forming the essence of vision. The gathering place of essence is the eyeball; the essence of bone manifests as the black eye (pupil and iris); the essence of blood manifests as the collaterals (ocular vessels); the gathering place of the essence of qi is the white eye (sclera); the essence of muscle manifests as the constraints (eyelids that control opening and closing), which wrap and gather the sinews and bones. The essence of blood and qi, combined with the meridians, forms the optic nerve system, which ascends to connect with the brain and emerges posteriorly from the middle of the neck. Therefore, if pathogenic factors attack the neck, especially when accompanied by bodily deficiency, and penetrate deeply, they follow the optic nerve system into the brain, causing dizziness or a sensation of rotation. This rotation pulls on the optic nerve system, causing tension, which in turn leads to vertigo and visual spinning. If pathogenic factors invade the essence within the eye, the affected essences fail to coordinate with each other. Consequently, the essence scatters, leading to diplopia (double vision), so that two objects are seen. The eyes are the gathering place of the essence of the five zang and six fu organs, the site where Ying (Nutritive) Qi, Wei (Defensive) Qi, Hun (Ethereal Soul), and Po (Corporeal Soul) constantly circulate, and the source of Shen (Spirit). Thus, mental exertion causes Hun and Po to scatter and will to become chaotic. Therefore, the pupil and black eye originate from Yin, while the white eye and red vessels originate from Yang; the interaction of Yin and Yang produces clear vision. The eyes are the messengers of the Heart; the Heart is the residence of Shen. Hence, if Shen and Jing (Essence) become disordered and cease to function normally, sudden perception of unusual phenomena occurs; when Spirit, Essence, Hun, and Po scatter and fail to harmonize, it is called "Huo" (delusion or confusion). Li Dongyuan stated: The twelve primary meridians and three hundred sixty-five collaterals all carry their blood and qi upward to the face and through the orifices. The clear Yang Qi ascends to the eyes to form visual essence, while its qi flows to the ears to enable hearing. Due to mental agitation, excessive workload, irregular diet, and overexertion, Spleen and Stomach weakness arises, and Heart Fire becomes excessive. This causes the blood vessels to boil and flow retrograde, allowing pathogenic factors to harm the orifices, resulting in blindness where one cannot perceive day and night. The essence and qi of the five zang and six fu organs are derived from the Spleen and ascend to penetrate the eyes. The Spleen is the head of all Yin meridians; the eyes are the master of all blood vessels. Therefore, Spleen deficiency causes the essence and qi of the five zang organs to lose their governance, preventing clear vision. The Heart is the Ministerial Fire (Jun Huo), the residence of the master's spirit, which should be calm and peaceful, whereas the Ministerial Fire (Xiang Huo) executes its commands. The Ministerial Fire refers to the Pericardium, which governs various diseases and ensures the eyes are nourished. However, due to overexertion and movement, this force acts recklessly; further damaged by pathogenic invasion affecting the blood vessels, various diseases arise. Physicians who fail to regulate the Spleen and Stomach, nourish the blood, and calm the spirit, treating symptoms rather than the root cause, do not understand the correct principles.

Note: This discussion regards the eyes as the master of the zang-fu organs, blood vessels, and essence/qi, providing a highly detailed explanation. It goes far beyond the secular limitations of merely adhering to the Five Wheels and Eight Palaces theories.