Amblyopia ("lazy eye"): what it is, causes and diagnosis

Sometimes it happens: one eye sees clearly, the other — as if through cloudy glass, and glasses do not remove this difference. This is what amblyopia, or "lazy eye," can look like: the eye itself looks normal, but vision in it never developed. I explain where this comes from, what astigmatism has to do with it, and what examinations show.

What amblyopia is and why the eye is called lazy

Amblyopia is when vision in one eye does not develop properly; both eyes are rarely affected. It occurs in approximately 1–1.5% of people and is considered the most common cause of visual impairment in children. The eye may look normal, but the brain "chooses" the other eye and stops using the weak one. That is why glasses and lenses do not remove the difference: the issue is not focus, but how the brain processes the image. Hence the word "lazy."

Causes of amblyopia

There are several causes. Strabismus — the eyes point in different directions, and the brain suppresses the image from one eye to avoid double vision. Refractive error — myopia, hyperopia, or astigmatism is more pronounced in one eye than in the other. Cataract or corneal opacity — the deprivation form: the eye does not receive a clear image. A psychogenic form is also distinguished separately, which occurs in hysteria together with other functional visual disorders.

Heredity also matters: if one of the parents had amblyopia, the risk for the child is higher.

Amblyopia and astigmatism: how they are related

Astigmatism is one of the refractive errors along with myopia and hyperopia. If it is not corrected, the image on the retina remains unclear, and the eye receives no stimulus to learn to see. The anisometropic form of amblyopia develops when the refractive power of the left and right eyes differs significantly.

Vision development occurs in childhood and adolescence, so treatment of amblyopia is most effective early. Positive treatment results in adults are insufficient for a statistical sample.

Signs of amblyopia

There may be no symptoms at all: often a "lazy eye" is first found during a routine eye exam. What others notice:

• the child closes one eye or squints when looking at something;
• the eyes point in different directions, strabismus is noticeable;
• the child cannot follow an object or person with their gaze;
• the head tilts when something needs to be examined;
• tired eyes, frequent eye rubbing, headaches, frequent blinking, problems catching a ball and falls.

A quick self-test: cover each of the child's eyes in turn with your hand. If you cover the good eye, the child may protest — this is a reason to show them to a specialist. This is an observation, not a diagnosis.

How amblyopia is diagnosed in children and adults

It begins with a vision test by an optometrist: the person looks at lamps or reads letters, and different lenses are placed before the eyes. Drops may be instilled to examine the fundus. Then the ophthalmologist assesses refractive asymmetry, the function of the extraocular muscles, and visual acuity in each eye separately, examines the eye with a slit lamp and the fundus. The diagnosis is made only after organic causes of vision loss have been excluded.

Preschool children are indicated for a complete ophthalmological examination; each eye is checked separately. If there has been amblyopia or strabismus in the family, the child is examined by an ophthalmologist.

Possible consequences and when to see an ophthalmologist

The main risk is persistent reduction in visual acuity if help does not come in time. The prognosis depends on timing: treatment is more effective if started before age 7, while vision is developing; according to other data, vision develops in childhood and adolescence, so treatment may be effective until approximately age 12.

An eye exam is scheduled if vision is a concern — one's own or a child's — and if there has been no examination for two years. For a preschool child — a routine examination, even without complaints.

Amblyopia itself is not a reason to call an ambulance; 103/112 — for sudden life-threatening signs, such as signs of stroke or severe head or eye injury.

This material is for reference: it does not replace a consultation with an ophthalmologist — only during an examination is each eye checked separately.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer