What is night blindness?

As long as our body lacks a certain substance, it will show abnormal behavior. The night blindness we are going to talk about today is actually a disease. This disease is caused by the lack of vitamin A in the body. Its symptoms are as its name suggests, including a much reduced vision at night, photophobia, and chronic diarrhea. This is something everyone should know.

Night blindness is actually very common in today's life, because many children nowadays are picky eaters, which can lead to malnutrition or a lack of a certain substance leading to some abnormal conditions in the body.

Vitamin A deficiency is a systemic disease caused by lack of vitamin A in the body. Its main pathological change is keratin degeneration in epithelial tissues throughout the body. Eye symptoms appear early and are significant, with reduced ability to adapt to darkness, followed by drying of the conjunctiva and cornea, and finally corneal softening and even perforation. Therefore, it is also known as night blindness, xerophthalmia and keratomalacia. This disease is more common in infants and young children with malnutrition and long-term diarrhea. The peak incidence is between 1 and 4 years old, and it is less common in those over 6 years old. This disease is more common in developing countries in Asia and Africa, and is not uncommon in remote areas of my country.

1. Symptoms

People suffering from vitamin A deficiency often have complications such as malnutrition, chronic diarrhea, chronic dysentery, long-term dietary abstention after measles, photophobia, and inexplicable blinking. Older children may have skin changes such as dryness and keratosis of hair follicles. In early and atypical cases, eye changes are mild and can be easily overlooked, especially in infancy. If there is a lack of vitamin A in food or if there is absorption difficulty, symptoms may appear within a few weeks. Infants with congenital biliary obstruction, hepatitis syndrome, and pneumonia may develop dry eyes within a short period of time.

2. Clinical manifestations:

1. Eye symptoms: They appear earlier, but in older children, eye symptoms often appear after other symptoms.

Night blindness: unclear vision and difficulty in orientation in dark environments, which can be easily overlooked if not carefully checked.

Bitot's spots: After several weeks to months, the conjunctiva and cornea gradually lose their luster and become abnormally dry when slightly exposed to air. The conjunctiva close to the sides of the cornea changes first, becoming dry and wrinkled, and the keratin epithelium gradually becomes regular, forming white spots of varying sizes that resemble foam.

Dry conjunctiva: The epithelial cells of the lacrimal gland degenerate, tear secretion decreases, and the lacrimal gland ducts are blocked by shed epithelial cells, resulting in even fewer tears. The children are afraid of light, feel dry and uncomfortable eyes, have eye pain, a feeling of sand being crushed in the eyes, and often blink or rub their eyes with their hands, which can easily lead to secondary infection. Gradual drying of the cornea

Other manifestations: turbidity, white opacity and softening. As the disease progresses, the cornea may ulcerate, and necrosis, perforation, iris detachment and corneal scarring may occur within a few days to weeks, eventually leading to blindness. The retina also has lesions and the fundus becomes dry. Both eyes usually become affected at the same time, sometimes one eye at a time. Unilateral disease is only occasionally seen.

2. Skin manifestations: The skin is prone to dryness, keratinization hyperplasia and desquamation.

Follicular keratosis pilaris: a chronic disease of keratosis pilaris, usually with a sandpaper-like roughness or chicken skin-like appearance on the extensor side of the limbs, with scattered, pinhead-sized, pointed, follicular papules with a keratin plug in the center, usually of normal skin color or dark red. There are usually no subjective symptoms, but occasionally there is mild itching. This symptom is rare in infants under 4 years old.

In addition, there are symptoms such as nails with many lines, loss of luster, cracking, and dry and easy-to-fall hair.

3. Other manifestations

Pyuria: refers to the presence of a large number of pus cells, i.e. white blood cells, in the urine. Clinically, the pus cells referred to are degenerated white blood cells, so the disease is also called leukocyturia. Patients usually have symptoms of systemic infection and poisoning such as pyelonephritis, chills and fever, nausea and vomiting, and body aches. Local symptoms include varying degrees of low back pain, bladder and wrist irritation, and stones.

Secondary infection of the respiratory tract: usually caused by secondary bacterial infection, which can easily lead to decreased immune function, proliferation and keratinization of the respiratory and urinary tract epithelium.

Loss of taste: The taste buds on the tongue lose their taste function due to epithelial keratinization, which affects appetite and some children may experience vomiting.

The above is some information about night blindness. I hope it can arouse everyone’s vigilance. Your body is your own. It will be useful only if you take good care of it and cherish it. If you don't deal with it after you get sick, your body will easily fail. The body also needs maintenance, and health is something you have to fight for yourself.