Amblyopia

Examinations and Tests

A doctor may diagnose amblyopia after detecting poor vision in one eye during an eye examination and ruling out other causes for this poor vision. Tests that find misaligned eyes (strabismus), unequal vision in the eyes, or any other condition that leads to amblyopia can help in the diagnosis.

Before the doctor tests your child's eyes, you will need to answer questions about:

• The child's symptoms.
• Any family history of vision problems.
• Other possible risk factors, such as low birth weight or premature birth.
• Whether teachers have noticed the child having trouble seeing the board or reading.

The doctor first checks the child's eyes to see if they both look in the same direction at the same time. A child with amblyopia may have an eye that wanders or lags behind the movement of the other eye.

For children age 2 and older, the doctor asks the child to identify or point to pictures or letters on the wall or on a hand-held chart. These tests measure how well the child sees shapes and details both up close and far away. They may reveal that the child's eyes have unequal vision (anisometropia).

Other tests, including dilating the child's eyes, may be done to determine the need for corrective lenses and to check the structure and function of the eyes. The doctor may also perform tests to detect cataracts and strabismus, both of which raise the risk of amblyopia.

Vision screening can be done by a family doctor or pediatrician. If a problem is detected, the child will be referred to an ophthalmologist or optometrist for a full vision examination.

Doctors may have difficulty performing vision screenings on some small children. In these cases, a technique called photoscreening may be used. In photoscreening, a special camera or video system is used to obtain images of the eye and its reflexes, requiring minimal co-operation from the child. While photoscreening is not a substitute for a normal vision test, it can provide information about sight-threatening conditions.

Other vision tests may be done to check the child's eyes and vision.

Early detection

Experts recommend screening to detect amblyopia, strabismus, and defects in visual acuity in children younger than 5 years.¹ Vision screening is recommended for infants who were either born at or before 30 weeks, whose birth weight was below 1500 g (3.3 lb), or who have serious medical conditions. The first screening is recommended between 4 and 7 weeks after birth.²

Do not wait if you detect possible signs of amblyopia in your child at an earlier age. No infant is too young for an eye examination by an ophthalmologist, and an examination should be done whenever you have questions about the health of your child's eyes.

The Canadian Paediatric Society recommends that all infants be screened by 6 months of age by a pediatrician, a family doctor, or an ophthalmologist.³ Newborns and infants should be screened for eye problems—such as cataracts—that can prevent light from entering the eye and cause amblyopia. Amblyopia from these causes is rare but serious. Without early treatment, the child may not develop normal vision in the affected eye.

Eye examinations for children and infants

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Author:	Robin Parks, MS	Last Updated: September 7, 2007
Medical Review:	Michael J. Sexton, MD - Pediatrics Anne C. Poinier, MD - Internal Medicine Christopher J. Rudnisky, MD, FRCSC - Ophthalmology
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