Many people are confused about the importance of eyeglasses for children. Some believe that if children wear glasses when they are young, they will not need them later. Others think that wearing glasses as a child makes one dependent on them later. Neither is true. Some children need glasses because they are genetically nearsighted, farsighted, or astigmatic. These conditions generally do not go away nor do they get worse because they are not corrected. For people with refractive errors, eyeglasses or contacts are necessary throughout life for good vision.
Nearsightedness (when distant objects appear blurry) typically begins between the ages of eight and fifteen but can start earlier. Farsightedness is actually normal in young children and not a problem as long as it is mild. If a child is too farsighted, vision is blurry or the eyes cross when looking closely at things. This is usually apparent around the age of two. Almost everyone has some amount of astigmatism (oval instead of round cornea). Eyeglasses are required only if the astigmatism is strong.
Unlike adults, children who need glasses may develop a second problem, called amblyopia or lazy eye. Amblyopia means even with the right prescription, one eye (or sometimes both eyes) does not see normally. Amblyopia is more likely to occur if the prescription needed to correct one eye is stronger than the other or if the prescription in both eyes is very strong. Wearing eyeglasses can prevent amblyopia from developing or may treat amblyopia if already present.
Children (and adults) who do not see well with one eye because of amblyopia, or because of any other medical problem that cannot be corrected, should wear safety glasses to protect the normal eye.
Amblyopia is poor vision in an eye that did not develop normal sight during early childhood. This condition, sometimes referred to as “lazy eye,” can run in families. The main causes of amblyopia are strabismus, refractive errors, or cloudiness of the eye tissues.
Amblyopia affects about three out of every 100 people. The best time to correct it is during infancy or early childhood, because after the first nine years of life, the visual system is normally fully developed and usually cannot be changed. It is recommended that children have their eyes and vision monitored by their primary care physician at their well-child visits. If there is a family history of amblyopia, children should be screened by an ophthalmologist (Eye M.D.).
Strabismus, or misaligned eyes, is the most common cause of amblyopia. The eye that is misaligned is ignored by the brain and “turns off.” A refractive error (meaning an eye is nearsighted, farsighted, or has astigmatism) is another cause of amblyopia. If one eye has a very different refractive error from the other eye, or if both eyes have a very strong refractive error, amblyopia can develop in the eye or eyes that are out of focus. The most severe form of amblyopia occurs when cloudiness of the eye tissues prevents any clear image from being processed. This can happen in conditions such as infantile or developmental cataracts.
Amblyopia is detected by finding a difference in vision between the two eyes or poor vision in both eyes. The ophthalmologist will also carefully examine the eyes to see if other eye conditions are causing decreased vision.
Amblyopia is treated by forcing the brain to use the affected eye or eyes. If refractive errors are present, they are corrected with eyeglasses or, less commonly, with contact lenses or refractive surgery. If a cataract or other cloudiness is present, surgery may be necessary to clear the line of sight. Strabismus may require surgery before, during, or after the amblyopia treatment. Patching or blurring the sound eye is then used to improve the vision by forcing the brain to recognize and process information from the affected eye or eyes. Once maximum vision has been obtained, treatment often needs to be continued at least part time for months to years to maintain the recovered vision. The earlier the treatment is begun, the more successful it will be.
Children are examined for any rare congenital problems at birth and at each well-child examination by the primary care physician, who will check for problems that may not be apparent to the parent or child but that could have serious consequences for the child’s vision. When the child is old enough, the primary care physician will perform a more formal vision screening examination. If the parent or the child’s doctor has any concerns, or if there is a family history of strabismus, amblyopia, or other eye conditions, the child should be referred to an ophthalmologist (Eye M.D.) for evaluation.
Conditions that the primary care physician will screen for include:
If the child is referred to an ophthalmologist, he or she will conduct a physical examination of the eyes, using eye chart tests, pictures, or letters to test the child’s ability to see form and detail of objects, and to assess for any refractive error (nearsightedness, farsightedness, and astigmatism).
Vision problems in children can be serious, but if caught in time and treated early, the child’s good vision can be protected.
Strabismus refers to misaligned eyes. Esotropia (“crossed” eyes) occurs when the eyes turn inward. Exotropia (“wall-eye”) occurs when the eyes turn outward. When one eye is higher than the other, it is called hypertropia (for the higher eye) or hypotropia (for the lower eye). Strabismus can be subtle or obvious, and can occur occasionally or constantly. It can affect one eye or shift between the eyes.
When young children develop strabismus, they typically have mild symptoms. They may hold their heads to one side if they can use their eyes together in that position. Or, they may close or cover one eye when it deviates, especially at first. Adults, on the other hand, have more symptoms when they develop strabismus. They have double vision (see a second image) and may lose depth perception. At all ages, strabismus is disturbing. Studies show school children with significant strabismus have self-image problems.
Strabismus usually begins in infancy or childhood. Some toddlers have accommodative esotropia. Their eyes cross because they need glasses for farsightedness. But most cases of strabismus do not have a well-understood cause. It seems to develop because the eye muscles are uncoordinated and do not move the eyes together. Acquired strabismus can occasionally occur because of a problem in the brain, an injury to the eye socket, or thyroid eye disease.
Amblyopia (“lazy eye”) is closely related to strabismus. Children learn to suppress double vision so effectively that the deviating eye gradually loses vision. It may be necessary to patch the good eye and wear glasses before treating the strabismus. Amblyopia does not occur when alternate eyes deviate, and adults do not develop amblyopia.
Strabismus is often treated by surgically adjusting the tension on the eye muscles. The goal of surgery is to get the eyes close enough to perfectly straight that it is hard to see any residual deviation. Surgery usually improves the conditions though the results are rarely perfect. Results are usually better in young children. Surgery can be done with local anesthesia in some adults, but requires general anesthesia in children, usually as an outpatient. Prisms and Botox injections of the eye muscles are alternatives to surgery in some cases. Eye exercises are rarely effective.
Although it can be caused by wind, smoke, or pollen, an excess of tears in children is often caused by congenital nasolacrimal duct obstruction, a condition in which a baby’s tear duct is blocked instead of draining normally through the duct into the nose. The condition can be recognized by tears that build up on the surface of the eye and overflow onto the eyelashes, eyelids, and down the cheek. Because the tears are not draining normally, babies will sometimes get infections, which can cause red, swollen eyelids and yellowish-green discharge.
Congenital nasolacrimal duct obstruction is usually caused by the failure of a thin tissue at the end of the tear duct to open properly when the child is born. It can also be caused by a lack of openings to the duct system at the eyelids, by infections, and by abnormal growth of the nasal bone, which pinches off the tear duct. Some infants may have excessive tearing due to narrow tear ducts rather than an obstruction. In this case, the tearing may be intermittent, occurring when the infant has a cold or during especially windy or cold weather. Finally, congenital glaucoma can cause tearing in children. This serious condition is often accompanied by other signs, including an enlarged eye, a cloudy cornea, and light sensitivity.
Most babies born with blocked tear ducts do not need treatment. More than 90% of blocked tear ducts clear by themselves before the child turns 1 year old. If treatment is necessary, the first course of action is usually tear duct massage, along with topical antibiotics to treat infection. The tear sac is located between the inside corner of the eye and the side of the nose. The purpose of massage is to put pressure on the tear sac for a few seconds to pop open the membrane at the end of the tear duct. This is most easily done by putting your hands on each side of the baby’s head and using your index fingers to press on the tear sac. This should be done several times a day, such as at after feedings or diaper changes.
In certain circumstances, tear duct probing, balloon tear duct dilation, or tear duct probing with tube placement may be necessary. Should your infant need treatment to remove a tear duct obstruction, ask your ophthalmologist (Eye M.D.) to discuss appropriate treatment options with you.