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The *Yuan Bing Shi* (Treatise on the Origin of Diseases) states: Blurred vision, redness and swelling of the eyes, and ulcers or membranes on the eyelids are all caused by Heat. Additionally, ptosis (drooping of the eyelid), commonly known as "eye blacking," is also due to Heat. In cases where a person who previously had normal vision suddenly cannot see, it is because the pathogenic Heat is extremely severe and stagnant. Some claim that blurred vision is caused by deficiency-cold of the Liver and Kidney; this is erroneous. They rashly assert that the Liver opens into the eyes and the Kidney governs the pupils, thus falsely attributing blurred vision to deficiency-cold. However, the Kidney corresponds to Water and Winter Yin; when deficient, it should manifest as Heat. The Liver corresponds to Wood and Spring Yang; when deficient, it should manifest as Cold. How can Kidney Yin and Liver Yang simultaneously present as deficiency leading to cold? Or, broadly speaking, if there is excess Yin and deficiency Yang within the Liver and Kidney, there would be no basis for blurred vision. Laypeople rashly believe that the Qi of the Liver and Kidney is depleted and cannot reach the eyes. They fail to realize that the classic texts state that extreme Heat causes one to close their eyes (i.e., visual impairment/blackout), which is certainly not caused by Cold. Furthermore, examining Zhang Zhongjing's words, in Shanghan diseases (Cold Damage disorders), when Heat reaches its extreme, one becomes unrecognizable, which constitutes blindness. The *Zheng Li Lun* (Theory of Orthodoxy) states: This results from extreme Heat stagnating in the eyes. If the eyes cannot see and the ears cannot hear, it is entirely due to the stagnation of Heat and the closure of Xuanfu (micro-pores through which Qi and fluids circulate). Qi, body fluids, blood vessels, Ying-Wei (Defensive and Nutritive Qi), and Spirit cannot ascend, descend, enter, or exit properly. Consequently, the severity of the disease varies according to the degree of stagnation. Thus, we know that Heat stagnating in the eyes leads to loss of vision. If vision is slightly blurred, objects appear harder to distinguish when viewed up close, because the Xuanfu of the eyes have become small and closed, resembling viewing objects through fine silk. Those who see things like fly wings flying have some closure in their Xuanfu. Those whose vision is blurred and who see floating black spots do so because extreme Heat manifests in the eyes. According to the principle "Excess brings harm, and control restores balance" (Kang ze hai, cheng nai zhi), tears are produced in reaction. The turbidity of Qi and fluids makes them visible; since they are very close, even minute spots are seen as black flowers. When wind triggers tearing and dim vision, it is because extreme Heat is controlled by Water transformation. Hence, the classics state that Jue syndrome (reversal syndrome) causes loss of vision. In Jue syndrome, Yang Qi congregates in the upper body, and Yin Qi congregates in the lower body. Yang congregating above means Fire shines alone; Yin congregating below means the feet are cold, and cold feet lead to distension. One unit of Water cannot overcome five units of Fire; therefore, the eyes become dim and blind. Thus, tearing continues uncontrollably upon exposure to wind. When Wind invades the eyes, Yang Qi remains internally guarded around the Jingming acupoint; this is Fire blazing the eyes, causing tearing upon seeing wind.

Commentary: This discussion details the causes of eye diseases arising from extreme Heat stagnation, simultaneous Jue of Yin and Yang, and the closure of Xuanfu, emphasizing the transformation of Fire and Heat. If the cause lies in spicy and hot diet, emotional disturbances, excessive influence of the Six Evils (pathogenic factors), or deficiencies and excesses of Qi and Blood, the theories of Li Dongyuan, Zhang Hezi, and Chen Wuyue are already comprehensive. However, there are also cases caused by Phlegm-Heat, Damp-Heat, or the ingestion of mineral-based drying and heating medicines. Additionally, after prolonged illness, weakness of Ying-Wei, insufficiency of Liver Qi and Kidney Yin, decline of Yuan Qi (Original Qi) and Essence, or conditions such as Tuo Ying (depletion of nourishment) may occur. These present distinct differences between Deficiency-Heat and Excess-Heat, and each requires differentiated treatment.