Your eye works a lot like a camera. Light rays focus through the lens on the retina, a layer of light-sensitive cells at the back of the eye. Similar to photographic film, the retina allows the image to be “seen” by the brain.

Over time, the lens of our eye can become cloudy, preventing light rays from passing clearly through the lens. The loss of transparency may be so mild that vision is barely affected, or it can be so severe that no shapes or movements are seen—only light and dark. When the lens becomes cloudy enough to obstruct vision to any significant degree, it is called a cataract. Eyeglasses or contact lenses can usually correct slight refractive errors caused by early cataracts, but they cannot sharpen your vision if a severe cataract is present.

The most common cause of cataract is aging. Occasionally, babies are born with cataracts or develop them very early in life. This condition is called congenital cataract. There are many causes of congenital cataract. Certain diseases can cause the condition, and sometimes it can be inherited. However, in most cases, there is no identifiable cause.

Treatment for cataract in infants varies depending on the nature of each patient’s condition. Surgery is usually recommended very early in life, but many factors affect this decision, including the infant’s health and whether there is a cataract in one or both eyes. If the child has a cataract in both eyes, it is possible that surgery may be delayed for years, or, depending on their severity, it may never become necessary. However, if only one eye is affected by cataract, the infant’s visual system can develop abnormally, and, if left untreated, serious vision problems and even vision loss can result.

If surgery is necessary, the ophthalmologist (Eye M.D.) will remove the eye’s cloudy lens and part of the surrounding lens capsule. Usually, strong eyeglasses or contact lenses are prescribed for infants after surgery. For babies over one year of age, an artificial intraocular lens (IOL) may be recommended instead to replace the eye’s natural lens. The ophthalmologist can recommend which procedure and optical correction is best for your child.

When only one eye has a cataract, amblyopia or “lazy eye” often is present or will develop even after the cloudy lens is removed. In this case, the eye is optically corrected with contact lenses, glasses, or an IOL. The amblyopia must be treated as well with patching or intentionally blurring the sound eye.

(c) 2007 The American Academy of Ophthalmology