Night blindness is a condition where the eyes struggle to adjust to sudden changes from darkness to light and vice versa. It often occurs in the evening or at night, in low-light environments. According to Doctor Luong Thi Anh Thu, High-Tech Eye Center, Tam Anh General Hospital Hanoi, night blindness can stem from many different causes.

Age

In older individuals, the retina and light adjustment reflexes decline with aging. This makes it difficult for the eyes to adapt to low-light conditions, resulting in poor night vision.

Retinal diseases

Rare inherited retinal diseases, such as retinitis pigmentosa (RP), cause gradual degeneration of the retina's light-sensing cells. These diseases often affect rod cells, leading to difficulty seeing at night from an early stage. Over time, central vision may decline, making it hard to see in low-light conditions.

Other rare inherited retinal diseases or gene mutations, including rod-cone dystrophy, choroidal disease, fundus albipunctatus, and Goldmann-Favre syndrome, also damage photoreceptor cells. This makes it difficult for the eyes to adapt to darkness.

Congenital night blindness, caused by abnormalities in visual signal transmission, makes it hard for patients to see in the dark from childhood, but their vision remains stable.

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

Diabetic retinopathy is common in individuals with long-standing diabetes. High blood sugar damages the small blood vessels that nourish the retina. When this nourishment is reduced, the eye's light-sensing cells function less effectively.

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

Vitamin A deficiency

Night blindness is often an early warning sign of vitamin A deficiency. This vitamin plays a role in producing rhodopsin, a pigment that helps the retina detect and process light in the dark. A deficiency causes the eyes to take longer to adapt to darkness, leading to difficulty seeing at night or when moving from a bright to a dark place. If this condition persists, the eyes can become dry, irritated, and easily damaged, severely impacting vision. Individuals with poor diets, excessive restrictive eating, or diseases that reduce fat absorption are at higher risk of vitamin A deficiency.

Effects after refractive surgery

Doctor Thu states that night blindness can also temporarily appear after some vision correction surgeries like Lasik or PRK. These procedures alter the shape of the cornea to improve vision but can also affect how light enters the eye. However, this is usually a transient phenomenon that gradually improves after several weeks to several months as the eyes fully recover.

Medication

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

Other eye conditions

In individuals with nearsightedness, farsightedness, or astigmatism, light does not focus correctly on the retina but is scattered, blurring images. Therefore, in the dark or at night, they often see less clearly, are prone to stumbling, or have difficulty observing while driving, creating a sensation similar to night blindness. Cataracts, glaucoma, and visual snow syndrome can also cause difficulty seeing at night.

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

Ly Nguyen