Nearsightedness in one eye (anisometropia) is a condition where one eye is nearsighted while the other eye is normal or has a different refractive error such as farsightedness or astigmatism. When there is a significant difference in vision, the brain often prioritizes signals from the stronger eye, neglecting the weaker eye. This can lead to the nearsighted eye worsening over time, causing eye strain, headaches, and difficulty with binocular vision coordination.

Master, Doctor Phung Van Thanh, from the High-Tech Eye Center at Tam Anh General Hospital Hanoi, states that nearsightedness in one eye can occur at any age, with varying symptoms and severity depending on the individual. In young children, anisometropia can impact their ability to perceive depth, coordinate vision, and affect the quality of their daily learning and activities. Doctor Thanh identifies several causes and risk factors for this condition.

Study habits and eye use

According to Doctor Thanh, favoring one eye over the other is a common cause of developing anisometropia. Children often lean to one side when reading, writing, or using a computer, causing one eye to work continuously. If this habit persists, the overused eye can become easily strained and is at a higher risk of becoming more nearsighted than the other, leading to a noticeable difference in vision between the two eyes.

Not wearing correct prescription glasses

Not wearing glasses or using an incorrect prescription means the nearsighted eye does not receive proper support, leading to an imbalance in vision. The stronger eye continues to be prioritized for processing images, while the nearsighted eye is neglected, making the anisometropia progressively worse. Individuals with nearsightedness should have their glasses accurately prescribed and follow their doctor's advice to maintain balanced vision between both eyes and slow the progression of myopia.

Doctor Thanh examines a young man's eyes. *Illustration: Tam Anh General Hospital Hanoi*

Lighting and study environment

Poor or excessively bright lighting during study can also contribute to the development of anisometropia. When lighting is insufficient or uneven, one eye has to work harder to perceive images, increasing the risk of eye strain and anisometropia. Eye injuries or damage to the cornea, lens, or retina can also cause a difference in vision between the two eyes.

Genetic, congenital factors

Genetics is a significant factor influencing anisometropia. If there is a family history of the condition, children are at a higher risk of developing it. This factor can affect the abnormal development of the eyeball or cornea, leading to one eye becoming nearsighted while the other maintains normal vision.

Doctor Thanh advises parents to observe their children's study and daily habits, ensure adequate lighting, prevent them from leaning to one side when reading or using electronic devices for extended periods, and schedule regular eye examinations.

By Thu Giang