Patient's question:
Why can't we see things at nightDoctor's answer:
It may be caused by a lack of vitamin A. It is recommended to see a doctor early for symptomatic treatment. Nyctalopia refers to poor night vision or the inability to see things in the dark, meaning poor visual function when transitioning from light to dark environments. It is primarily due to the dysfunction of rod cells in the retina, with symptoms such as impaired dark adaptation or peripheral retinal lesions. Nyctalopia can be caused by eye diseases themselves or systemic diseases. It can be congenital or acquired, and sometimes has a genetic cause, such as:(1) Systemic disease-induced nyctalopia: Vitamin A deficiency caused by systemic diseases such as insufficient intake, malnutrition, wasting diseases, artificially fed infants, liver disease, and gastrointestinal diseases, leading to nyctalopia in the early stages, followed by conjunctival and corneal dryness. Severe cases may develop corneal erosion, ulceration, or perforation.
(2) Refractive interstitial nyctalopia (pseudo-nystagmus): Poor night vision occurs when the disease affects the peripheral cornea or more severely. Cloudiness in the periphery of the lens, such as corneal cataracts in the form of a flower, traumatic cataracts, or early cataracts in the elderly, results in poor vision at night or in low light.
(3) Nyctalopia caused by iris and pupil abnormalities: Adhesions between the iris and the lens, deformed pupils with only a small central opening, or drug-induced pupil constriction.
(4) Ophthalmic disease-induced nyctalopia: Congenital cases include retinal dysplasia and retinitis pigmentosa. Acquired cases include progressive glaucoma, optic neuritis, optic atrophy, retinal periphlebitis, diabetes, hypertension, and arteriosclerotic retinopathy.
Why do children get nyctalopia? How should it be treated? Nyctalopia is primarily caused by vitamin A deficiency, most commonly seen in infants and young children. The reasons for vitamin A deficiency include:
First, prolonged feeding of infants with starchy foods, skimmed milk, and legumes without timely supplementation of vitamin A-rich foods;
Second, gastrointestinal diseases (e.g., diarrhea) and liver/biliary diseases (e.g., chronic hepatitis) in infants that impair the absorption and utilization of vitamin A;
Third, rapid growth in infants with insufficient vitamin A supply.
Infants with vitamin A deficiency often have difficulty seeing in dim light, frequently squinting due to dry conjunctiva, photophobia, and even corneal dryness, loss of luster, corneal opacity, softening, and ulcers. Additionally, symptoms such as dry, scaly skin, brittle hair prone to falling out may occur.
For mild cases, vitamin A can be taken orally in doses of 25,000–50,000 IU per day, divided into 2–3 doses (concentrated vitamin A capsules, each containing 25,000 IU). Severe cases may receive vitamin AD injections at a dose of 0.5–1 mL deep intramuscularly once daily, with improvement expected within 3–5 days. Additionally, maintaining eye cleanliness and using 0.75% chloramphenicol eye drops can be beneficial.
How can nyctalopia be prevented? Prevention of this condition involves the following four points:
First, pregnant women should maintain a varied diet during pregnancy, consuming foods rich in carotene and vitamin A, such as eggs, animal livers, carrots, and vegetables like tomatoes.
Second, actively prevent or treat chronic diseases in infants and supplement vitamin A early. Breastfeeding infants or artificially fed infants should be supplemented with vitamin A-rich foods. The physiological daily requirement of vitamin A for infants is generally 30 IU per kilogram of body weight. Premature infants should receive concentrated cod liver oil at a dose of 3,000–5,000 IU per day.
Fourth, avoid unnecessary dietary restrictions for certain conditions, especially during measles, and ensure adequate vitamin A supplementation.