A newborn cannot properly focus on an object at birth. Babies must learn to focus both eyes in the same way that they learn to control their motor skills. If a child is incapable of focusing both eyes, they will experience double vision. This is an annoying way to see the world; consequently, they will learn to rely on only one eye for vision. Prolonged use of only one eye deteriorates the nerves to the unused eye, resulting in the condition called amblyopia, which is often called “lazy eye”.


Amblyopia can be caused by a visual obstruction such as cataracts, a refractive error that occurs when the curve of the eye is incorrect, or by strabismus which is an abnormal alignment of the eyes. Whatever the abnormality, the effects of amblyopia are one or more of the following:

  • abnormal vision (poorer than 20/20)
  • eye misalignment
  • uncoordinated eye movement
  • loss of depth perception
  • squinting or closing one eye while focusing


As with any vision problem, treatment is determined after a thorough ophthalmic exam. Besides the use of a standard eye chart, the ophthalmologist may also perform tests that measure how misaligned the eyes are (prism test) and a depth perception test (stereopsis test). None of the tests are invasive or cause any discomfort.

When amblyopia is detected in an infant, certain testing may not be possible. The doctor may choose to strengthen the misaligned eye by placing a patch over the stronger eye so that the infant is forced to use the weaker eye. If the problem is not corrected as the child grows, then glasses will be prescribed to help correct and balance the eyes. If the amblyopia was caused by an obstruction such as cataracts, then surgery to remove the cataracts may be performed. Laser surgery to improve amblyopia has had limited success and is not standard practice for treatment at this time.

Note: It is vital to the correction of amblyopia that treatment begins as early as possible. A child’s nervous system continues to develop through infancy and can only be corrected during this sensitive period. Doing nothing and waiting will only cause permanent, irreversible damage.

This educational material is provided by Dialog Medical.
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