What is a Congenital Cataract?
A congenital cataract is an opacity (cloudiness) of the lens of the eye that is present at, or develops shortly after, birth. The human lens, located behind the pupil, focuses light onto the retina, allowing a clear image to be formed (read How the Eye Works to learn more). A cataract blocks or distorts the image that would normally reach the retina. During the first five to seven years of life, a clear image is required in order for the connections between the eye and the brain to develop normally. Thus, a congenital cataract causes the immature visual system to be deprived of the stimulation needed for normal development. Unlike in adults, if left untreated, permanent visual loss may occur.
How Vision Is Affected
If the cataract is small, there may be only slight blurring of vision with near-normal visual development. However, if the cataract is larger, it can affect visual development in a significant way. In some cases, this can lead to amblyopia (lazy eye) an irreversible loss of vision if not treated. The eye is not "blind," as peripheral vision usually remains and the eye may still be able to distinguish light and dark.
Congenital cataracts can affect one or both eyes. In bilateral cases, the cataract may be denser in one eye than the other. If the image is less blurred in one eye as compared to the other, this eye will develop vision preferentially, with additional suppression of visual development in the eye with the cataract that is worse.
- Clouding of the lens, often evident at birth without special viewing equipment and appearing as a whitish discoloration in an otherwise normally dark pupil
- Failure of an infant to show visual awareness of the world around him or her (particularly when present in both eyes)
- Nystagmus (unusually rapid spontaneous eye movements)
- No symptoms may be present if the cataract occurs only on one side or is not severe. This can often be overlooked without a proper eye examination and does not mean that treatment is not required
Some congenital cataracts impair visual development only to a small degree and may never require surgery. However, removal of the cataractous lens by surgery is the most effective means of treatment in most cases. Once the natural lens is removed, optical correction with a contact lens and/or glasses is usually necessary. Lens implants (which are always used in adult cataract surgery) are becoming more common in young children. Because clear vision is essential for early visual development, a diagnosis within the first few weeks of life is important. If surgery is only needed on one eye, an optimal outcome is ensured by patching the healthier eye for several hours a day in early childhood. This forces the brain to accept the image from the operated (weaker) eye and helps the visual system develop.
Complications may occur following any surgery. The most worrisome ones after cataract surgery in infants are increased intraocular pressure (glaucoma) with subsequent optic nerve damage or a retinal detachment, both of which can cause further vision loss. Additional treatments or surgery may be required to treat these complications.