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Vitamin A deficiency, old age, retinal diseases, and genetic factors are common causes of night blindness.

Night blindness is a condition where the eye has difficulty adjusting to sudden changes from darkness to light and vice versa, often occurring in the evening or at night, in low-light environments. According to Dr. Luong Thi Anh Thu, High-Tech Eye Center, Tam Anh General Hospital, Hanoi, night blindness can stem from various causes.

Age

In older adults, the retina and light-adjusting reflexes decline with aging, making it difficult for the eyes to adapt to low light conditions and resulting in poor night vision.

Retina diseases

Genetic retinal diseases are less common, typically retinitis pigmentosa (RP), a group of diseases that cause gradual degeneration of the light-sensitive cells of the retina. Because it often affects the rod cells, patients experience difficulty seeing at night from an early stage. Over time, central vision may deteriorate, making it difficult to see in low light conditions.

Some other rare inherited retinal diseases or gene mutations, such as rod-cone cell dystrophy, choroidal disease, fundus albipunctatus, Goldmann-Favre syndrome, etc., also damage light-sensitive cells, making it difficult for the eye to adapt to darkness.

Congenital night blindness is caused by abnormalities in the transmission of visual signals, making it difficult for patients to see in the dark from a young age, but their vision remains stable.

Night blindness makes it difficult for patients to see in the evening or at night. (Image created by AI)

Diabetes retinopathy is common in people with long-standing diabetes. High blood sugar can damage the small blood vessels that nourish the retina. When the supply is reduced, the light-sensitive cells in the eye function less effectively.

Macular degeneration affects the central area of ​​the retina, causing reduced central vision and distorted images. While not a typical cause of night blindness, macular degeneration can still make it difficult for patients to see in low light conditions, especially when distinguishing details.

Vitamin A Deficiency

Night blindness is often an early warning sign of vitamin A deficiency. This vitamin is involved in the production of rhodopsin – a pigment that helps the retina recognize and process light in the dark. When the body is deficient, the eyes take longer to adapt to darkness, making it difficult to see at night or when moving from a bright to a dark place. If this condition persists, the eyes may become dry, irritated, easily damaged, and seriously affect vision. People with poor diets, excessive dietary restrictions, or diseases that reduce fat absorption are at a higher risk of vitamin A deficiency.

Effects of Refractive Surgery

Dr. Thu says that night blindness can also temporarily occur after some vision correction surgeries such as Lasik or PRK. These interventions change the shape of the cornea to improve vision but can also affect the path of light into the eye. However, this is usually only a transient phenomenon and gradually improves after a few weeks to a few months as the eye fully recovers.

Medications

Some medications can affect pupil function and the eye's ability to adjust to light, making it difficult for users to see in the dark.

Other Eye Conditions

In people with myopia, hyperopia, or astigmatism, light does not converge correctly on the retina but is scattered, causing images to become blurry. Therefore, in the dark or at night, they often see less clearly, are more prone to falls, or have difficulty observing while driving, creating a feeling similar to night blindness. Cataracts, glaucoma, and snow vision syndrome can also cause difficulty seeing at night.

Dr. Thu noted that night blindness not only causes inconvenience in daily life but can also be an early sign of many eye diseases or underlying nutritional deficiencies. Patients should not be complacent but should visit an ophthalmologist for examination, diagnosis of the cause, and timely treatment to avoid the risk of long-term vision loss.