Your child seems to act and play normally for her age. She can pick out objects from across the room, and she doesn't seem to have any trouble seeing the TV. But could she have a hidden vision problem without knowing it?
Amblyopia is a common eye condition that is often hidden behind the appearance of a child's seemingly good vision. Amblyopia is also known more familiarly as "lazy eye". Many people think that a lazy eye is the condition when one eye turns in or out, while the other eye looks straight. That condition is called strabismus, but it almost always leads to amblyopia. A true lazy eye occurs when the brain ignores the signals sent by one eye, causing the child to really use just one eye all the time. This is usually because one eye is weaker or doesn't focus as well as the other eye. When the brain has a choice between a clear image from one eye and a blurry image from the other eye, the clearer eye always wins. And the blurry eye gets ignored. You could say that it's not really lazy eye, but lazy brain!
This eye condition is more common in premature babies, and it also runs in families. That is why it is important to provide a complete medical and family history at the time of your appointment.
What are the risk factors for amblyopia?
- High amounts of astigmatism,
- High amounts of nearsightedness (myopia) or farsightedness (hyperopia)
- Unequal development of the eyes
- Congenital cataracts (clouding of the lens of the eye)
- Strabismus or "crossed eyes"
Because the brain ignores the blurry eye, a child with two normal appearing eyes may never realize one is lazy. Both eyes appear straight and the child sees well, but only out of one eye. Because of this, children don't complain and parents don't realize anything is wrong. In fact these children usually live with amblyopia for years before it is discovered.
If amblyopia is diagnosed early, it can usually be corrected with treatment. But as a child grows older the brain loses some of its plasticity (how easy it is to train the brain to develop new skills), making it harder, or nearly impossible, to fix amblyopia in older kids and adults. That's why it's so important for infants and young children to have a comprehensive eye exam.
What Are the Signs of Amblyopia?
If you notice one eye turning in or out, your child should have a comprehensive eye exam to check for strabismus and amblyopia. Preschoolers with amblyopia can show signs of unusual posture when playing, such as head tilting, clumsiness or viewing things abnormally close. Squinting and rubbing of the eyes can also be an indication of a vision problem.
Most of the time, however, there are no obvious signs of amblyopia. The child typically does not complain. Children do not know what normal vision should look like. Sometimes the condition is discovered when the child begins to read. The school nurse may check your child's vision with a vision screening at school. But it might be possible to pass a vision screening test and still have a lazy eye. Only an eye exam performed by an eye doctor can make a definitive diagnosis of amblyopia or strabismus.
So When Should My Child Have an Eye Exam?
At Opticare Vision Center, we perform InfantSEE examinations, which are no-cost eye exams given to infants between 6 and 12 months of age. The "magic time" for a first eye exam is at 10 months, says Dr. Josiah Young of the Newport office. "At 10 months, enough of the visual system is developed for a smaller range of expected normal results," says Dr. Young. "Most of the infant exam is just getting the child's attention and using our special lights to look inside the eyes," he says. The infant exam will usually require the use of dilating eye drops, which are formulated specifically for children and safe to use.
After that, the best time for an eye exam is after 3 years old or around the time they start preschool. The preschool eye exam involves a lot of games for the child to play. While the doctor plays the games with the child, the doctor is examining the child's eyes. By the time the exam is over, the kids have had fun and gotten their eyes checked in the process. The preschool eye exam may or may not require eye drops for dilating the pupils.
What is the Treatment for Amblyopia?
In mild to moderate cases of amblyopia, glasses correction alone can often be enough to get the child seeing normally. But in some cases including severe amblyopia, additional treatment with occlusion (patching one eye) is required to force the brain to use the lazy eye. Once we can get the brain using the amblyopic eye, the vision usually improves. Sometimes the treatment will include both glasses and patching therapy. Regular follow-up appointments are necessary to track the child's progress and ensure the treatment is working properly.
We Learn to See
As mentioned before, lazy eye is more like lazy brain. Vision is a sense that the brain learns to use after we are born. We don't see perfectly right when we are born. Much of the process of developing good vision takes place in the first 12 months of life and continues to refine through the next 5 or 6 years. So if the brain favors one eye over the other during vision development, the other eye does not develop clear vision. Whether we use patches to occlude the good eye or eye drops to relax the focusing muscles of the good eye, we are trying to train the brain to use the lazy eye. This re-establishes the eye-brain connection with the weaker eye and gradually improves vision in that eye.
Your child's eye doctor will tailor a therapy plan to best treat the lazy eye. This could involve wearing glasses, patching for a certain number of hours daily, or taking eye drops at certain times. Most of this is worked around the child's school schedule as to not affect his or her academic performance.
Because the brain learns to see early in life, amblyopia treatment is most effective when done as young as possible. Amblyopia treatment with patches or drops may be minimally effective in improving vision as late as the early teen years (up to age 14). So it is important to identify and treat amblyopia as early as possible.
The key to improving their vision is being compliant with the prescribed therapy. Children must wear their glasses or contact lenses consistently to be successful. Your eye doctor will prescribe a schedule for patching, drops, or vision therapy eye exercises and recommend a follow-up schedule to check your child's progress.
Amblyopia: Take-home Message - We Learn To See
The comprehensive eye exam is designed to detect all vision conditions, especially lazy eye. There's a window of time where vision develops in children. Our brain learns to see best during this window. Once that window is closed, around 10 to 12 years old, the vision loss can be permanent. But if we catch it early, we can treat amblyopia and help a child regain the clear vision in both eyes that they deserve. That's why it is so important to have your child's eyes checked by an eye doctor at an early age.