A cataract is a cloudiness of the lens, the normally clear focusing structure of the eye. Light must pass through this "fogged" window to reach the retina and transmit the image to the brain. As a result of the cloudiness, images are blurred. The greater the degree of cataract, the greater the distortion of the image.
A congenital cataract is a cloudy lens that develops during the fetal period and is present at birth. In most cases, the cause isn't known. However, cataracts are associated with certain medical conditions, such as galactosemia (a metabolic disease), intrauterine infection (such as rubella), or other type of maternal disease during pregnancy. In some patients there is a family history of congenital cataracts. Symptoms may include: obvious clouding of the lens, a seeming lack of awareness of surrounding visual objects, or unusual rapid eye movements (nystagmus, caused by an inability of the eye to focus).
Congenital cataracts can occur in one eye or both. When only one eye is affected, the brain prefers to use the image coming from the good eye and may learn to ignore or suppress the image from the clouded eye. That can lead to an underdevelopment of vision in the eye with the cataract.
The Scleral Fixated Intraocular Lens
The usual treatment for cataract is removal of the clouded lens and replacement with an intraocular implant, which functions as an artificial lens. In the past, doctors used to treat congenital cataracts by simply removing the natural lens. That left patients with little sight. Even with very thick glasses, many had severe vision difficulties. Contact lenses can help, but not all patients can wear them.
One option for these patients is a newer type of lens, called the scleral fixated lens. It's made of the same material as the standard intraocular lens. However, the newer lens is permanently stitched to the sclera, or white part of the eye. The scleral fixated lens may be a good option for older patients who had lens removal for congenital cataracts, but never received an implant. The lens will not help patients whose poor vision is caused by retinal disease. Fortunately, cataract surgery has advanced tremendously over the last several years and doctors are often able to implant intraocular lenses in infants.
For general information on cataracts or congenital cataracts:
American Society of Cataract and Refractive Surgery, 4000 Legato Rd., Suite 850, Fairfax, VA 22033, www.ascrs.org
MEDLINEplus – www.nlm.nih.gov