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The Secret Life of the Brain
History of the Brain 3-D Brain Anatomy Mind Illusions Scanning the Brain The Episodes:

Episode 1: The Baby's Brain - Infant Cataracts FAQ
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xray of brain
Brain scans are taken to locate cataracts in newborn babies.

1. What is a cateract?

Any opacity in the lens of the eye is called a cataract. The lens sits behind the pupil and focuses light into the eye. Some cataracts are mere specs in the lens and have no visual impact. Other cataracts can occupy the entire lens and block all formed images from being focused into the eye.

2. Can a cateract damage the eye permanently?

Cataracts themselves are rarely injurious to an eyeball. Their main impact is the blurring of vision. However, if left untreated, particularly in young children, the brain can "forget" how to use the eye and this results in "lazy vision" called amblyopia. This can result in permanent visual damage. To prevent this, the cataract is removed and the good eye patched to help the brain re-learn how to use the cataract eye.

Only rarely, can the cataract rupture outside of its protective lens membrane capsule (the capsular bag), at which time the eye itself can be damaged by an inflammation response (iritis) or an elevation of the pressure in the eye (glaucoma). This is very uncommon, particularly in children, unless the cataract was caused by an injury, which ruptures the capsule.

3. Is the a physical difference between a cateract in an infant's eye and a cateract in an older person's eye? Why is one more common than the other?

photo of baby
After the removal of the cataract, a patch is put over the baby's good eye or else her brain will never learn to use the other eye to see.

The types of lens opacities we see in children are different than those in adults. Adults tend to get a browning and hardening of the lens where as children cataracts tend to be more white and localized in special zones of the lens which reflect the developmental process that makes the lens. However, the end result is the same: blurred vision.

All people will get cataracts in their eyes if they live long enough. This is a natural effect of aging. Children only get cataracts when there is a specific abnormality in the development of the lens of the eye, often due to a gene abnormality. Some cataracts in children are the secondary effect of an underlying disease, genetic syndrome, or medication.

Why is it beneficial to cover the good eye in event of congenital cateracts?

By covering the good eye after the cataract is removed, the brain is forced to use the cataract eye and thus re-start the vision development that was delayed while the brain was relying on the good eye.



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