bubble_chart Concept

Crab's eye refers to the black of the eye, where due to the rupture of congealed fat, the iris protrudes from the ruptured area, resembling a crab's eye, hence the name. It is commonly seen in severe conditions such as congealed-fat nebula (purulent keratitis), upward rushing of yellow fluid (hypopyon), malnutrition involving the eye (keratomalacia), etc. (Mujing Dacheng) states: "In diseases such as congealed fat, yellow fluid, and wood ulceration, the black of the eye is eroded and ruptured, and the black dragonfly (iris) emerges from the ruptured area."

This condition was first mentioned in Michuan Yanke Longmu Lun. It is also referred to as "crablike eye (corneal perforation and iridoptosis)", "crablike eye (corneal perforation and iridoptosis)".

Crab's eye is similar in symptoms to "blackish iridoptosis", but they are not the same condition. Zhengzhi Zhunsheng once pointed out: "This condition and blackish iridoptosis appear similar but are treated very differently. Blackish iridoptosis originates from within the jelly and does not emerge due to rupture, hence they are fundamentally different." This indicates that blackish iridoptosis gradually bulges before the black of the eye ruptures. Therefore, it is not within the scope of this discussion.

bubble_chart Pattern Analysis

1. Excess Fire in the Liver and Gallbladder︰The onset is rapid, with unbearable eyeball pain, restlessness, photophobia and tearing, hyperemia of the ocular conjunctiva. The iris protrudes from the ruptured nebula on one side of the black of the eye, resembling a crab's eye, and in severe cases, it may appear as large as a black soybean. Contracted pupil (iridocyclitis) is difficult to observe or may be biased toward the ruptured side of the black of the eye. Accompanied by dark urine, constipation, bitter taste in the mouth, dry throat, and flushed face. The tongue is red with yellow coating, and the pulse is wiry and rapid. This is due to intense fire forcing upward, eroding the black of the eye, and the iris protruding from the rupture, hence the unbearable pain, photophobia, tearing, and contracted pupil (iridocyclitis), making it difficult to identify. Additional symptoms include a flushed face, bitter taste in the mouth, dry throat, dark urine, constipation, and a wiry, rapid pulse. The condition is acute and severe. Treatment should focus on clearing and purging the liver and gallbladder, using the Gentian Liver-Draining Decoction. If fire is excessive and yin is damaged, the Liver-Draining Decoction may be used.
2. Qi Deficiencyliver Heat︰The onset is slow, with mild eyeball pain. The iris protrudes from the ruptured area of the black of the eye, accompanied by slight photophobia and tearing. The pupil is visible, resembling the shape of a bitter apricot seed, and is displaced toward the ruptured area of the black of the eye. There is mental fatigue and lack of strength, a red tongue with thin yellow coating, and a fine, weak, and rapid pulse. This condition arises from constitutional qi deficiency combined with stagnant heat in the liver channel. Therefore, the iris protrudes without distension, photophobia is mild, and although the pupil is small, it remains recognizable, resembling a bitter apricot seed and leaning toward one side of the ruptured area. Additional symptoms include mental fatigue and lack of strength, with a fine, weak, and slightly rapid pulse. The condition is mild and slow in progression. Treatment should focus on tonifying qi to support healthy qi, clearing the liver, and draining fire. The recommended formula is Saposhnikovia Root Liver-Draining Powder, with antelope horn removed and raw gypsum added.
3. Yin Deficiency︰If the crab's eye (protruding iris) persists for a long time, the protruding iris becomes loose and flat without pain, the white of the eye appears pale red, and there is dryness and discomfort, accompanied by dizziness, tinnitus, soreness and weakness in the waist and knees, a red tongue without coating, and a thin, rapid pulse. This is often due to liver and kidney yin deficiency, with deficient fire scorching the black of the eye, causing the protruding iris to become loose and flat without pain, along with pale redness in the white of the eye, dryness, and discomfort, as well as dizziness, tinnitus, and soreness and weakness in the waist and knees. The pulse is thin and rapid. Although the condition is mild, it is prolonged and difficult to cure. It can be differentiated from the symptoms and signs of crab's eye caused by liver-gallbladder excess fire or qi deficiency with liver heat. The treatment should focus on nourishing the liver and tonifying the kidney, nourishing yin and reducing fire. Recommended formulas include Zhen Shen Jue Ming Wan or modified Qing Shen Tang.

The condition of "crab eye" affects the black of the eye, which corresponds to the liver internally. Therefore, crab eye caused by excessive liver-gallbladder fire is characterized by a sudden and severe onset, with symptoms such as a bulging and protruding iris, photophobia, aversion to heat, and unbearable pain. In cases of crab eye due to qi deficiency and liver heat, the pathogen is of a deficiency type and milder; although the iris protrudes, the pain and photophobia are not severe. Crab eye caused by yin deficiency with effulgent fire results from water failing to nourish wood, leading to excessive wood and fire. In this case, the iris protrudes but is slack, flat, and without pain.

bubble_chart Documentation

1. Yizong Jinjian-Yanke Xinfa Yaojue: "The symptom of crab eye, where the black eye protrudes like a bean or a pearl, resembling a crab's eye, is extremely painful, with astringent tears and photophobia. Initially, it is solid, hard, and extremely painful; over time, it becomes deficient, soft, and painless. It is generally caused by the accumulation of heat in the liver and gallbladder rushing to the eyes, and the deficiency heat in the kidneys affecting the eyes. For the solid type, Liver-Draining Decoction is appropriate; for the deficient type, use Zhen Shen Jueming Pill."