What are cataracts?
Think of the lens of the eye like the lens of a camera. A cataract is when there is whitening or clouding of the natural lens of the eye, which should be clear to allow light into the eye. There are many different types of cataracts and not all cataracts cause vision loss. Some cataracts are small and do not affect vision. A child may be born with a cataract, but cataracts can also develop through childhood. It is estimated that 200,000 children around the world are blind due to cataracts.
How does a cataract affect vision?
Light enters the eye and hits the retina, the part in the back of the eye that senses light and sends these signals to the brain. A cataract may stop light from reaching the retina and thus prevent the eye from seeing. If there is a cataract blocking light from the entering the eye in a young child, a child may not develop his/her visual system and this can lead to amblyopia. In kids, prompt treatment is necessary to prevent permanent vision loss. This is different from a cataract in an adult where the visual system has already developed before the cataract formed. You can learn more about this concept of amblyopia here.
A clear lens allows light to enter the eye and reach the retina. The retina is the part of the back of the eye that senses light and turns the light into signals to send to the brain. These signals then travel from the eye to the visual cortex. The visual cortex is the part of the brain that turns these signals into vision.
What causes a cataract?
A congenital cataract happens when there is an abnormal development of the lens while the baby is still in the womb (uterus). Cataracts can also result from infections, genetic problems, or sometimes they form spontaneously. Children with Down's syndrome, Marfan's, or Homocystinuria are a few examples of genetic conditions that can be associated with cataracts. This list by no means is exhaustive and pediatric ophthalmologists screen many children with different genetic and metabolic conditions to make sure we don't miss a cataract.
Not all cataracts are created equal.
There are three parts to the human lens just like there are three parts to a peanut M&M. In a human lens, there is a center part (called the nucleus), a middle part that wraps around the nucleus (called the cortex), and a capsule that wraps around the entire lens. In a peanut M&M, the peanut, which is the center, would be the nucleus. The chocolate around the peanut would be the cortex. The candy shell would be like the lens capsule. Each of these different parts of the lens can get cloudy and cause a different appearance to a cataract.
The 3 parts of a lens are like the 3 parts of a peanut M&M candy! There is a center (the nucleus), a middle (the cortex), and an outer layer (capsule).
How do you treat a cataract?
Small cataracts that do not seem to be affecting vision can be carefully watched over time. We may try a combination of glasses and patching to see if this can prevent amblyopia. We remove a cataract if there are any signs of significant vision problems. Cataracts that are significantly affecting vision are often removed as soon as possible. If there is a delay in removal, we worry that this will interfere with normal development of the vision part of the brain.
Surgery is not the end of the story. Parents should know that following removal of a cataract, a child may need to use a combination of glasses, contact lenses, and patching following his/her surgery to improve vision. Depending on the age the surgery is done, these therapies may last for years.
How do I know if my baby has a cataract?
If the cataract is big or dense, you may notice it as a white spot on your child's eye. However, cataracts are often hard to see and can manifest instead as a child's eye crossing in or drifting out from the vision loss. Sometimes a child may have a rapidly changing glasses prescription in one eye from a cataract. A child may also squint or choose to close one eye and turn his/her face to use the better seeing eye. Note, there are different eye conditions, not just cataracts, that can cause face turns and crossing in/drifting out of the eyes. If you are noticing that your child has any of the above eye findings, please discuss this with your pediatrician to get a referral for an eye exam.
This illustration shows different examples of how a cataract may present in a child. The child may develop a white pupil or white spot on his/her eye. A child's eye might begin to cross in or drift out. A child may frequently start turning his/her face to look at objects with the better seeing eye. A child may have a rapidly changing glasses prescription in one eye.
As a reminder, everything on this blog is for educational use only and not medical advice. If you have any concerns that your child may have a cataract, please discuss this with your pediatrician for evaluation.
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