经云∶肾足少阴之脉，动则病生，目KT KT 如无所见。又云∶少阴病目KT
KT无所见者，阴内夺，故目KT KT 无所见也，此盖房劳目昏也。左肾阴虚，右肾阳
虚。刘河间曰∶目HT 不明，热也。然玄府者，无物不有，人之脏腑皮毛，肌肉筋膜，骨
髓爪牙，至于世人万物，尽皆有之，乃气出入升降之道路门户也。人之眼耳鼻舌身意，神识
能为用者，皆升降出入之通利也，有所闭塞者，不能为用也。目无所见，耳无所闻，鼻不知
臭，舌不知味，筋痿骨痹，爪退齿腐，毛发堕落，皮肤不仁，肠胃不能渗泄者，悉由热气怫
郁，玄府闭塞，而致气液血脉，荣卫精神，不能升降出入故也。各随郁结微甚，而为病之重
轻。故知热郁于目，则无所见也，故目微昏者，至近则转难辨物，由目之玄府闭小，如隔帘
视物之象也。或视如蝇翼者，玄府有所闭合者也。或目昏而见黑花者，由热气甚而发之于目
亢则害，承乃制，而反出其泪泣气液眯之，以其至近，故虽微而亦见如黑花也。楼全善曰:
诚哉！河间斯言也，目盲耳聋，鼻不闻臭，舌不知味，手足不能运用者，皆由玄府闭塞，
而神气出入升降之道路不通故也。故先贤治目昏花，如羊肝丸用羊肝引黄连等药入肝，解肝
中诸郁。盖肝主目，肝中郁解，则目之玄府通利而明矣。故黄连之类，解郁热也；椒目之类
解湿热也；茺蔚之类，解气郁也；芎归之类，解血郁也；木贼之类，解积郁也；羌活之类
解经郁也；磁石之类，解头目郁。坠邪气使下降也，蔓菁下气通中，理亦同也。凡此诸剂
皆治气血郁结目昏之法，而河间之言，信不诬矣。至于东垣、丹溪治目昏，用参 补血气
亦能明矣。又必有说通之。盖目主气，血盛则玄府得通利，出入升降而明，虚则玄府不能
出入升降而昏，此则必用参 四物汤等剂，助气血营运而明也。
《黄帝内经》记载：足少阴肾经的经脉，发生病变时会产生病症，患者眼睛视物模糊不清，好像看不见东西一样。又说：少阴病出现眼睛视物模糊、看不见的症状，是因为阴精内里亏虚耗夺，所以眼睛看不清。这大概是由于房事过度导致的视力昏暗。左肾阴虚，右肾阳虚。
刘河间说：眼睛视物不明，是由热邪引起的。然而“玄府”这一概念，无处不在，人的脏腑、皮毛、肌肉、筋膜、骨髓、爪牙，以及世间万物，全都具备它，它是气机出入升降的道路和门户。人的眼、耳、鼻、舌、身、意，神识之所以能发挥作用，都是因为气机的升降出入通畅无阻；如果有闭塞之处，就不能发挥作用。眼睛看不见，耳朵听不到，鼻子闻不到气味，舌头尝不出味道，筋脉痿软、骨骼痹痛，指甲脱落、牙齿腐朽，毛发坠落，皮肤麻木不仁，肠胃不能正常排泄，这些都是由于热气郁结，玄府闭塞，导致气、液、血、脉、营卫、精神等物质不能正常升降出入所造成的。根据郁结程度的轻重不同，疾病的严重程度也随之变化。因此知道热邪郁结于眼部，就会导致视物不见。所以眼睛轻微昏花的人，凑近看反而更难分辨物体，这是因为眼睛的玄府闭小，就像隔着帘子看东西一样。或者视物如见蝇翅飞舞，是因为玄府有所闭合。或者眼睛昏花且看见黑点飘动，是因为热邪极盛而发于眼部，“亢则害，承乃制”（事物发展到极端就会受到制约），反而流出泪液和气液眯眼，因为距离极近，所以即使是微小的黑点也能看见，如同黑花一般。
楼全善说：“确实如此！刘河间的这番话，眼睛失明耳聋，鼻子闻不到气味，舌头尝不出味道，手脚不能活动运用，都是由于玄府闭塞，神气出入升降的道路不通畅所导致的。”所以先贤治疗目昏眼花，例如使用羊肝丸，用羊肝作为引经药，引导黄连等药物进入肝脏，解除肝脏中的各种郁结。因为肝开窍于目，肝中的郁结得以解除，那么眼睛的玄府就能通利明亮。所以黄连这类药物，是解除郁热的；椒目这类药物，是解除湿热的；茺蔚草这类药物，是解除气郁的；川芎、当归这类药物，是解除血郁的；木贼这类药物，是解除积滞之郁的；羌活这类药物，是解除经络之郁的；磁石这类药物，是解除头目之郁，镇压邪气使其下降的；蔓菁能下气通中，道理也是相同的。所有这些方剂，都是治疗气血郁结导致目昏的方法，而刘河间的言论，确实没有虚假。至于李东垣、朱丹溪治疗目昏，使用人参、黄芪补益气血，也能使视力恢复明亮。其中必定有疏通理气的说法。因为眼睛的功能主要依赖气机，血液旺盛则玄府得以通利，气机出入升降正常从而视力清晰；如果虚弱，则玄府不能正常出入升降而导致昏花，这种情况必须用人参、黄芪配合四物汤等方剂，辅助气血运行营运从而使视力恢复明亮。
The *Huangdi Neijing* (Yellow Emperor's Inner Canon) states: When the Foot-Shaoyin Kidney Meridian (Kidney Channel of Foot-Shaoyin) is disturbed, disease arises, and the eyes appear blurred as if unable to see. It further states: In Shaoyin disease, when one cannot see due to blurred vision, it is because Yin essence is depleted internally; thus, the eyes fail to see clearly. This is likely dimness of vision caused by sexual exhaustion. The left Kidney suffers from Yin deficiency, while the right Kidney suffers from Yang deficiency.
Liu Wansu stated: Blurred vision is caused by heat. However, the "Xuanfu" (Mysterious Pores/Orifices) exists everywhere—in the human viscera, skin, hair, muscles, fascia, bone marrow, nails, and teeth, as well as in all things in the world. They are the pathways and gates for the entry and exit, ascent and descent of Qi. The reason why the human senses—eyes, ears, nose, tongue, body, and mind—and consciousness can function is that the ascent, descent, entry, and exit of Qi are smooth and unobstructed. If there is any blockage, function is lost. Inability to see with the eyes, hear with the ears, smell odors with the nose, taste flavors with the tongue, flaccidity of sinews, bi-syndrome of bones, falling nails, rotting teeth, falling hair, insensitivity of the skin, and inability of the intestines and stomach to excrete—all these result from the stagnation of heat and the closure of the Xuanfu, preventing Qi, fluids, blood, vessels, Ying-Wei (Defensive and Nutritive Qi), and spirit from ascending, descending, entering, and exiting. Depending on the severity of the stagnation, the severity of the disease varies. Therefore, knowing that heat stagnates in the eyes leads to blindness. Thus, those with slight blurring of vision find it harder to distinguish objects when looking closely, because the Xuanfu of the eyes are narrowed, resembling the effect of viewing objects through a curtain. Or seeing spots like fly wings indicates that the Xuanfu are partially closed. Or experiencing blurriness with floating black spots is due to excessive heat manifesting in the eyes. According to the principle "Excess leads to harm, and control follows" (Kang ze hai, cheng nai zhi), tears and fluid secretions may obscure vision. Because these are very close to the eye, even minute particles are visible like black flowers.
Lou Quanshan said: "Indeed! Liu Wansu's words are true. Blindness, deafness, inability to smell, inability to taste, and inability to move hands and feet are all caused by the closure of the Xuanfu, blocking the pathways for the entry, exit, ascent, and descent of Shen-Qi (Spiritual Qi)." Therefore, ancient sages treated blurred vision, such as using Yanggan Wan (Sheep Liver Pill), employing sheep liver as a guiding herb to direct herbs like Huanglian (Coptis Rhizome) into the Liver to resolve various stagnations in the Liver. Since the Liver opens into the eyes, resolving Liver stagnation allows the Xuanfu of the eyes to become clear and bright. Thus, Huanglian-type herbs resolve heat stagnation; Jiaomu (Sichuan Pepper Seed) type herbs resolve damp-heat stagnation; Chongwei Cao (Leonurus Herba) type herbs resolve Qi stagnation; Xionggui (Ligusticum Chuanxiong and Angelica Sinensis) type herbs resolve Blood stagnation; Muzei (Equisetum Hiemale) type herbs resolve accumulated stagnation; Qianghuo (Notopterygium Root) type herbs resolve meridian stagnation; Cishi (Magnetitum) type herbs resolve head-and-eye stagnation, weighing down evil Qi to make it descend; Manjing (Brassica Pekinensis) directs Qi downward and unblocks the middle, following the same logic. All these formulas are methods for treating blurred vision caused by Qi and Blood stagnation, confirming that Liu Wansu's statements are not unfounded. As for Li Dongyuan and Zhu Danxi treating blurred vision, they used Renshen (Panax Ginseng) and Huangqi (Astragalus Membranaceus) to tonify Qi and Blood, which also restores clarity. There must be an explanation involving unblocking. Since vision primarily relies on Qi, abundant Blood allows the Xuanfu to be patent, enabling normal ascent/descent and entry/exit for clear vision; deficiency prevents the Xuanfu from functioning normally, leading to blurriness. In such cases, one must use formulas like Renshen combined with Siwu Tang (Four Substance Decoction) to assist the circulation and operation of Qi and Blood to restore clarity.