Library

The *Huangdi Neijing* (Yellow Emperor's Inner Canon) states: The pupil and black eye follow the principle of Yin, while the white part of the eye and red vessels follow the principle of Yang. Thus, when Yin and Yang combine, visual acuity is achieved; this indicates that the eye possesses both Yin and Yang attributes. (The full text is found in the chapter "Visual Disturbances and Hallucinations".) It further states: The essence and qi of the five zang organs and six fu organs all ascend to the eye, forming the essence of vision. The cavity of the eye is called the "eye"; the essence of bone manifests as the pupil, the essence of sinews as the black eye, the essence of blood as the collateral vessels, the essence of qi as the white of the eye, and the essence of muscle as the eyelids (constraints). These wrap and gather the essence of sinews, bones, blood, and qi, merging with the meridians to form the optic nerve system, which connects superiorly to the brain and emerges posteriorly from the middle of the neck. This indicates that the eye embodies the functions of the five zang and six fu organs. (The full text is found in the chapter "Visual Disturbances and Hallucinations".) Later generations held that the inner and outer canthi belong to the Heart, the upper and lower eyelids belong to the Spleen, the white of the eye belongs to the Lung, the black eye belongs to the Liver, and the pupil belongs to the Kidney, a theory known as the "Five Wheels" (Wu Lun), which is presumably based on these texts. There is also a theory of the "Eight Palaces" (Ba Kuo), but it lacks meaning and evidence, so it is not included here.

There are two primary zang-fu organs governing the eyes: one is the Liver. The classics state: The color of the East is green, which communicates internally with the Liver, opens into the eyes, and stores essence in the Liver. It also states: When one lies down, blood returns to the Liver; the Liver receives blood and thus enables vision. Furthermore: Liver qi communicates with the eyes; when Liver qi is harmonious, one can distinguish the five colors. The second is the Heart. The classics state: The Heart combines with the vessels, and all vessels belong to the eyes. Li Dongyuan later extended this reasoning to include the Spleen, as described below.

[Li Dongyuan] in the *Treatise on the Generation of Five Zang Organs* states: All vessels belong to the eyes, and the eyes enable vision only when nourished by blood. In the *Da Huo Lun* (Treatise on Great Confusion) of the *Zhen Jing* (Needle Classic), Volume Nine, it is said: If the heart is troubled and restless, diet is irregular, and labor/exertion is excessive, then Spleen-Stomach deficiency occurs, and Heart fire becomes excessive. Consequently, the hundred vessels boil, blood vessels reverse their flow, evil pathogens harm the orifices, and just as the sun and moon lose their brightness at dawn, vision is impaired. The essence and qi of the five zang and six fu organs are all derived from Spleen Earth and ascend to penetrate the eyes. The Spleen is the head of all yin organs, and the eyes are the root of blood and qi. Therefore, if the Spleen is deficient, the essence and qi of the five zang organs lose their control and cannot bring clarity to the eyes. The Heart is the Ministerial Fire (Jun Huo), the spirit of the master, which should be quiet and peaceful. The Assistant Fire (Xiang Huo) acts on its behalf; the Assistant Fire refers to the Pericardium-Luo, which governs the hundred vessels to nourish the eyes. Due to labor and exertion, the vital energy acts recklessly. Coupled with invasion by evil pathogens damaging the blood vessels, various diseases arise. Any physician who fails to regulate the Spleen and Stomach, nor nourishes blood and calms the mind, treating symptoms rather than the root, does not understand the correct principles.

Yang governs dispersion; Yang deficiency leads to tightness at the corners of the eyes, resulting in entropion and trichiasis (curled eyelashes). Yin governs contraction; Yin deficiency fails to contract, leading to dilation of the pupil and blurred vision.

[*Lingshu*] states: The outer corner of the eye near the face is the outer canthus, the inner corner near the nose is the inner canthus, the upper part is external, and the lower part is internal. (See *Dian Kuang Pian*). To diagnose eye pain: if red vessels extend from top to bottom, it is Taiyang Disease (Disease of the Bladder/Small Intestine channel); if from bottom to top, it is Yangming Disease (Disease of the Stomach/Large Intestine channel); if moving from outside inward, it is Shaoyang Disease (Disease of the Gallbladder/Triple Burner channel). Taiyang Disease should be treated with warming and dispersing methods; Yangming Disease with purgative and cooling methods; Shaoyang Disease with harmonizing methods. (See *Lun Ji Zhen Chi Pian*)

[*Baoming Ji*] discusses: Eye diseases located in the fu organs are exterior syndromes and should be treated by dispelling wind and clearing heat. Those located in the zang organs are interior syndromes and should be treated by nourishing blood and calming the mind. Acute onset indicates an exterior syndrome, which is easy to treat. Chronic illness indicates an interior syndrome, which is difficult to treat. For dispelling wind and clearing heat, *Xieqing Wan* (Clearing the Liver Decoction) is the primary formula. For nourishing blood and calming the mind, *Dingzhi Wan* (Calming the Mind Pill) is the primary formula. For women, *Shudihuang Wan* (Prepared Rehmannia Pill) is used. For those with obesity, excess qi, and upward rising wind-heat causing blurry and gritty eyes, *Huai Zi San* (Sophora Seed Powder) is indicated. This arises from turbid qi ascending from the chest; if severe, it may lead to Phlegm-Jue, which can also damage the eyes. Keeping the chest qi clear naturally prevents this condition. Additionally, excessive use of cold medicines for eye diseases damages qi; over time, eyes become gradually dim and weak, fluctuating between clarity and darkness, unable to see objects clearly. This is a sign of blood loss. *Shugan Dihuang Wan* (Dried Rehmannia Pill) and *Xiaoqi Dingzhi Wan* (Qi-Dispersing and Mind-Calming Pill) should be used together for nourishment. For unclear vision and seeing black spots, this is termed Kidney Qi weakness, requiring tonification of Kidney Water; *Zhujing Wan* (Staying in Scenery Pill) is appropriate. For sudden blindness, since the eyes are located at the convergence of all yang channels, if yin pathogen obstructs them, it indicates fullness of wind evil within, suggesting potential unforeseen serious illness.