夫眼内红丝是云翳之根，云翳是红丝之苗。红丝
满目，各有经络。若不循经络，一概用退翳之药，则
不效矣。
如翳自内 而出，手太阳、足太阳病也，宜服羌
活胜风汤加苍术、蔓荆子；翳自锐 而入，客主人斜
下者，足少阳、手少阳、手太阳之病也，加胆草、 本。
人参，翳自目丝而下，足厥阴、手少阴病也，倍加柴
胡、黄连；翳自抵过而上，手太阳之病也，加五味子、
木通。各按经络加减，自然随手奏效。
须欲退云翳，先退红丝，看那一经红丝先到，开
手退后到的。三年之丝紫红色，二年之丝木红色，一
年之丝鲜红色。先退鲜红，次退木红，后退紫红。按
经施治，自有奇功。胜风汤方见真人《秘诀》。既有云
翳红丝，用《秘诀》吹法并点法。
眼当暴发肿痛、热气炙人时，红丝云翳未生，
宜利大小便，火由大小便而去，令火有出路，不上攻
于目，则病除矣。若到红丝云翳已生，开手遽然用凉
药通利大小便，寒凉冰住云翳，即成锢疾。往往见
治目者，不论翳障有无，开手即用泻火之剂，以致寒
凉伤胃，生意不上升，诸病生焉，且仅云翳不退已哉？
初用梨汁膏，次用白玉锭，末用扫雾丹点。
经云目得血而能视，是血之精粹上注于目而为明
也。病久，过用寒凉，伤其脾胃；过于发散，耗其精
华。以致气血不能流通，云翳遂不能去。治年老或日
久云翳，必先补气养血。气血足，云翳自然活动易退。
血不足，固是目不得血也；火盛血耗，亦是目不得血
也。不宜点。
眼睛内部的红色血丝是云翳（角膜瘢痕或混浊）的根本，而云翳则是红色血丝的表现。如果满布红丝，它们分别归属于不同的经络。如果不遵循经络辨证，一概使用退翳的药物，就不会见效。
例如，如果云翳从内眦向外发展，属于手太阳小肠经和足太阳膀胱经的病证，适宜服用羌活胜风汤，并加入苍术、蔓荆子；如果云翳从外眼角锐角处向内侵入，客主人穴（耳前区域）斜下方者，属于足少阳胆经、手少阳三焦经、手太阳小肠经的病证，需加入龙胆草、藁本、人参；如果云翳从眼角的血络向下发展，属于足厥阴肝经、手少阴心经的病证，需加倍使用柴胡、黄连；如果云翳从下方向上方蔓延至瞳孔边缘以上，属于手太阳小肠经的病证，需加入五味子、木通。各按经络进行加减用药，自然能随手奏效。
想要消除云翳，必须先消退红丝。观察哪一条经络的红丝最先出现，就先治疗后出现的红丝。三年的红丝呈紫红色，两年的红丝呈枯木色（暗褐色），一年的红丝呈鲜红色。先消退鲜红色的，其次消退枯木色的，最后消退紫红色的。按照经络施治，自有奇效。胜风汤的方剂详见真人《秘诀》。既然已有云翳和红丝，使用《秘诀》中的吹法（将药粉吹入眼中）和点法（滴眼药水）。
当眼睛突然暴发肿痛、热气灼人时，红丝和云翳尚未形成，适宜通利大小便，使火热之邪通过大小便排出，让火有出路，不向上攻冲于目，疾病就能消除。如果等到红丝和云翳已经形成，一着手就急忙使用寒凉药物通利大小便，寒凉之气会使云翳凝结固化，从而变成顽固难愈的疾病。常常看到治疗眼病的人，不论是否有云翳障蔽，一着手就用泻火的药剂，导致寒凉损伤脾胃，生机不能上升，各种病症由此产生，况且仅仅是云翳不退罢了？初期使用梨汁膏，接着使用白玉锭，最后使用扫雾丹点眼。
经典记载：“眼睛得到血的滋养才能视物”，这是血的精粹上注于眼睛而使其明亮的缘故。病程长久，过度使用寒凉药物，会损伤脾胃；过度使用发散药物，会耗损精华。导致气血不能流通，云翳于是无法去除。治疗年老或日久形成的云翳，必须先补气养血。气血充足，云翳自然会松动易于消退。血不足，固然是因为眼睛得不到血的滋养；火势旺盛耗伤血液，也是眼睛得不到血的滋养。这种情况不宜点药。
The red filaments within the eye are the root of the nebula (corneal opacity/scarring), and the nebula is the sprout of the red filaments. When red filaments fill the eye, they each correspond to specific meridians. If one does not follow the meridian patterns and indiscriminately uses medicines to dissipate opacities, there will be no effect.
For instance, if the opacity develops from the inner canthus outward, it is a disease of the Hand-Taiyang (Small Intestine) and Foot-Taiyang (Bladder) meridians; one should take Qianghuo Shengfeng Tang (Notopterygium Decoction for Overcoming Wind) with added Cangzhu (Atractylodis Rhizoma) and Manjingzi (Vittatis Fructus). If the opacity enters from the lateral acute angle and extends obliquely downward toward the Kerenren acupoint (area anterior to the ear), it is a disease of the Foot-Shaoyang (Gallbladder), Hand-Shaoyang (Sanjiao), and Hand-Taiyang (Small Intestine) meridians; add Longdancao (Gentianae Radix), Gaoben (Ligustici Rhizoma et Radix), and Renshen (Ginseng Radix). If the opacity descends along the ocular blood vessels, it is a disease of the Foot-Jueyin (Liver) and Hand-Shaoyin (Heart) meridians; double the dosage of Chaihu (Bupleuri Radix) and Huanglian (Coptidis Rhizoma). If the opacity ascends from below to above the limbus, it is a disease of the Hand-Taiyang (Small Intestine) meridian; add Wuweizi (Schisandrae Chinensis Fructus) and Mutong (Akebiae Caulis). By adjusting prescriptions according to the meridians, efficacy will naturally follow immediately.
To eliminate the nebula, one must first dissipate the red filaments. Observe which meridian's red filament appears first, and begin treatment on those appearing later. Red filaments present for three years appear purplish-red; those present for two years appear wood-red (dark brown); those present for one year appear bright red. First dissipate the bright red, then the wood-red, and finally the purplish-red. Treating according to the meridians yields miraculous results. The formula for Shengfeng Tang is found in Zhenren's *Mijue* (Secrets). Since both nebula and red filaments are present, use the blowing method (blowing medicinal powder into the eye) and dropping method (applying eye drops) from *Mijue*.
When the eye suddenly erupts with swelling, pain, and burning heat, before red filaments and nebula have formed, it is appropriate to promote urination and defecation. This allows the fire pathogen to exit through the urine and stool, providing an outlet so that fire does not attack upward to the eye, thereby curing the disease. However, once red filaments and nebula have already formed, if one hastily uses cold-natured medicines to promote urination and defecation, the coldness will freeze and solidify the nebula, turning it into an entrenched and difficult-to-cure condition. It is often seen that practitioners treating eye diseases, regardless of whether opacities exist, immediately use purgative formulas to drain fire. This damages the stomach and spleen with coldness, prevents the vital energy from ascending, and gives rise to various ailments, let alone merely failing to resolve the nebula? Initially use Lizhi Gao (Pear Juice Ointment), subsequently use Baiyu Ding (White Jade Tablet), and finally use Saowu Dan (Fog-Sweeping Elixir) as eye drops.
The classics state: "The eye sees only when nourished by blood," meaning that the essence of blood flows upward to the eye to provide clarity. In chronic diseases, overuse of cold-natured medicines damages the stomach and spleen; overuse of dispersing medicines depletes the essence. This leads to stagnation of qi and blood, causing the nebula to persist. In treating nebula resulting from old age or long duration, one must first tonify qi and nourish blood. When qi and blood are sufficient, the nebula naturally becomes mobile and easy to dissipate. Insufficient blood means the eye lacks nourishment; excessive fire consuming blood also means the eye lacks nourishment. In such cases, topical application is not suitable.