Nyctalopia refers to the symptom of having normal vision during the day but being unable to see or experiencing mental confusion at dusk or in dark rooms.

Zhubing Yuanhou Lun states: "Some people have clear vision during the day but cannot see at night, which is commonly referred to as nyctalopia." Later generations also called it "nyctalopia," "chicken blindness," or "chicken dim-sightedness." Since nyctalopia is often seen in children, Yinhai Jingwei separately named it "childhood nyctalopia."

bubble_chart Pattern Analysis

1. Liver Blood Deficiency︰After sunset, vision becomes dim and objects cannot be seen clearly, with symptoms such as dry and itchy eyes, photophobia, frequent blinking, fluctuating severity, and in severe cases, ulceration of the black of the eye leading to nebula. Accompanied by dizziness, palpitations, a pale tongue with thin coating, and a fine, wiry pulse. This condition is often caused by constitutional weakness, blood loss, or blood deficiency after illness, resulting in insufficient liver blood. This leads to a lack of nourishment for the aqueous and vitreous humors, initially causing dryness in both eyes and later progressing to inability to see at dusk. Blood deficiency fails to nourish the head and eyes, hence dizziness; the heart lacks blood nourishment, leading to palpitations, a pale tongue with thin coating, and a fine pulse. Treatment should focus on nourishing blood and tonifying the liver, with modified prescriptions such as Zhuanguang Wan. It is advisable to consume more animal livers, such as pork, lamb, or chicken liver, to supplement liver function and enhance nutrition.
2. Liver-kidney Yin Deficiency︰Bright vision during the day but blindness at night, narrow visual field, dry and uncomfortable eyes, irritability and insomnia, sore waist and weak legs, dizziness and dry mouth, seminal emission, red tongue with scant coating, thin and rapid pulse. This condition often develops from night blindness due to insufficient liver blood, or may result from constitutional yin deficiency and excessive sexual activity. The liver and kidneys are simultaneously affected. Depletion of yin essence leads to emptiness of the marrow sea, failing to nourish the brain marrow and brighten the eyes, hence blindness at night and narrow visual field. Insufficient kidney water causes dizziness and tinnitus. Emptiness of the lumbar region results in soreness and weakness of the waist and legs; yin deficiency generates internal heat, leading to irritability, insomnia, and dry mouth; yin deficiency stirs fire, causing insecurity of the essence gate and seminal emission. Red tongue with scant coating, thin and rapid pulse. Treatment should focus on nourishing water to moisten wood, supplemented by nourishing the heart and tranquilizing the mind. The recommended formula is Six-Ingredient Rehmannia Pill combined with Sour Jujube Decoction with modifications.
3. Spleen Qi Deficiency︰The eyes cannot see in dim light, with narrowed vision, mental fatigue lack of strength, shortage of qi, and reluctance to speak. The tongue texture is pale, with thin white coating, and the pulse is thin and soft. This is often caused by irregular eating, overexertion, or excessive contemplation damaging the spleen, leading to middle qi deficiency and impaired spleen function, preventing the clear yang qi from ascending and nourishing the head and eyes, resulting in night blindness. Spleen qi deficiency leads to mental fatigue lack of strength, shortage of qi, reluctance to speak, pale tongue texture, and thin, soft pulse. Treatment should focus on tonifying qi, strengthening the spleen, replenishing the middle, and raising yang. The recommended formulas are Middle-Tonifying Qi-Replenishing Decoction or tonifying qi Congming Decoction combined with Jueming Yeling Powder with modifications.
4. Spleen-kidney Yang Deficiency︰Clear vision during the day but poor vision at night, decreased visual acuity, narrowed visual field, cold body and limbs, soreness and weakness of the waist and knees, impotence and premature ejaculation, diarrhea before dawn, clear and abundant urine, or dribbling after urination. The tongue texture is pale and swollen with a white and greasy coating, and the pulse is deep and thin, with both chi pulses faint. It often develops from spleen qi deficiency, so the latter is mild while the former is severe, and they often interact as cause and effect. Night blindness due to spleen-kidney yang deficiency mostly arises from the progression of spleen qi deficiency or constitutional yang deficiency, resulting in deficiency of both the spleen and kidney, failure of clear yang to ascend, and insufficient qi to nourish the eyes, leading to night blindness. Yang deficiency generates external cold, hence the cold body and limbs; spleen-kidney yang deficiency and the decline of yang qi cause soreness and coldness in the waist and knees, impotence and premature ejaculation, and even diarrhea before dawn, a pale and swollen tongue, and a deep and thin pulse. Treatment should focus on warming and tonifying the spleen and kidney, with prescriptions such as the Kidney Qi Pill from the Golden Cabinet, or modified Whole Deer Pill.
5. Deficiency of Both Qi and Blood︰Dizziness, blurred vision, inability to see at dusk, narrowed field of vision, pale complexion, palpitations, insomnia, mental fatigue, lack of strength, shortness of breath, spontaneous sweating, pale tongue texture, and weak, thin pulse. This is often caused by chronic illness or constitutional spleen-stomach weakness, leading to insufficient generation and transformation of qi and blood, which fails to nourish the head and eyes, resulting in inability to see at dusk and a narrowed field of vision. Qi deficiency causes shortness of breath and spontaneous sweating, blood deficiency leads to palpitations and insomnia, while dual deficiency of qi and blood results in dizziness, blurred vision, pale complexion, a pale and swollen appearance, and a weak, thin pulse. Treatment should focus on tonifying and replenishing qi and blood, with modifications of Bupleurum Ginseng Atractylodes Decoction recommended.

There is a connection between insufficient liver blood, liver-kidney yin deficiency, spleen deficiency with weak qi, and spleen-kidney yang deficiency, which involves the progression from blood deficiency to yin deficiency, and from qi deficiency to yang deficiency. The first two syndromes are related to yin blood deficiency, while the latter two are related to yang qi deficiency, making them relatively easy to distinguish.

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1. Michuan Yanke Longmu Lun: "liver-deficiency nyctalopia internal visual obstruction: In the initial stage of this eye condition, there is often itching or dryness, with intermittent episodes of dim vision. In the severe stage, vision is lost at dusk, and only straight purgation objects can be seen. It is advisable to take Liver-Cleansing Decoction and Liver-Draining Decoction for recovery."
2. Michuan Yanke Longmu Lun: "high-wind sparrow-vision internal visual obstruction (pigmentary retinopathy): In the initial stage of this eye condition, there is accumulated heat in the liver and kidney deficiency fatigue, accompanied by wind invasion. Insufficient liver qi leads to this condition. The symptoms differ from the previous condition, with distinct visual disturbances, such as only seeing emetic therapy objects, followed by bluish blindness (optic atrophy). It is advisable to take Liver-Tonifying Powder and Huanjing Pills for recovery."
3. Michuan Yanke Longmu Lun: "pediatric malnutrition involving eye (keratomalacia) external ophthalmopathy: In the initial stage of this eye condition, it is caused by brain heat, sores on the head, or prolonged nyctalopia, with diarrhea and hidden invasion, pain, and difficulty in opening the eyes due to tears. Heat in the diaphragm and liver wind invasion lead to initial symptoms of frequent itching and dryness, accompanied by behaviors like rubbing eyebrows, biting nails, and rubbing the nose, resulting in nebula formation, redness, swelling, pain, and difficulty in opening the eyes. The diaphragm becomes hard, and a white membrane covers the eye, causing photophobia and a tendency to lie face down, avoiding lifting the head. This condition should not be treated with moxibustion on the head or face, as it may harm the eyes. Eye drops are especially contraindicated."
4. Zhengzhi Yaojue．Ocular Pattern Treatment: "Some people develop dim vision or nyctalopia due to a vegetarian diet. Food generates essence, and its deficiency leads to insufficient nourishment for the eyes, resulting in reduced vision."