This is a condition which develops during the early years of childhood; it is quite rare and only affects 2 percent of children in the UK. In most cases, it affects only one eye but it may also affect both eyes. Having a lazy eye affects vision because it distorts the rays of light coming into the eye and subsequently disrupts the messages sent from the retina to the brain.

What causes a lazy eye?

Ambylopia is often caused by another eye condition; there are several conditions which may contribute to a lazy eye; these include:

  • Strabismic ambylopia: this form of ambylopia is caused by a squint in the eye; this is the most common cause of a lazy eye. A squint usually affects juts one eye and makes the eye look in a different way to the other eye. The brain ignores signals from the affected eye in order to prevent double vision; over time, the eye stops working and becomes lazy.
  • Anisometropic ambylopia: this type of ambylopia occurs as a result of problems with the refraction process (this is the way in which the direction of the light rays is changed when they come into the eye from another medium (usually the air). These problems may be caused by myopia, hyperopia or astigmatism. The eye becomes lazy as a result of the brain ignoring the signals from the eye that is most affected by long or short sightedness.
  • Ametropic ambylopia: this condition affects vision in both eyes; it is usually the result of significant refractive problems and may cause constant blurred vision.
  • Stimulus deprivation ambylopia: this is the rarest form of ambylopia but it is the most serious. It occurs when the eye is prevented from seeing; this is usually the result of another eye condition such as glaucoma or cataracts but it may also be caused by an injury to the eye.

Symptoms of a lazy eye

Some children have a very obvious lazy eye but many are much less visible. Having a lazy eye prevents the person from being able to focus on objects properly or see images clearly; other symptoms include squinting and having a slightly droopy eyelid.

Treating a lazy eye

Treatment is most effective when children are still very young so it is important to get your child examined and treated quickly if you suspect they may have a lazy eye. Treatment is used to correct vision and treat any conditions which may be contributing to the lazy eye. Usually, wearing glasses will help to address conditions such as long or short sightedness and surgery will be used to treat conditions such as cataracts. Once underlying conditions have been treated, specialists will work to improve the child’s vision; treatments include surgery, the use of eye drops and wearing a patch (this involves placing a small patch on the eye that works in order to encourage the affected eye t start working).

Guide to Eye Conditions

Eye Conditions Intro

Laser Eye Surgery Guide

Ambylopia lazy eye





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Long sightedness

Looking after your eyes

Short sightedness