Nearsightedness, Farsightedness and Astigmatism
What nearsightedness, farsightedness and astigmatism really mean in the eyes of children
Farsightedness, nearsightedness and astigmatism. The terms may be familiar, but parents want to know what they mean and how they differ in order to understand the treatment for their child’s eyes. The American Association of Pediatric Ophthalmology and Strabismus (AAPOS) offers simple explanations for hyperopia (farsightedness), myopia (nearsightedness) and astigmatism.
Hyperopia (farsightedness) means the eyes are out of focus more for near than for distance. A very farsighted child may have blurred vision at distance and at near. A mildly farsighted child may actually see completely normal at distance and near but will compensate for the farsightedness by focusing or “accommodating,” which a child can do to a much larger degree than an adult. In addition, a moderately farsighted child may see well at distance and near but experience eyestrain or crossed eyes when focusing (accommodating) to compensate for the uncorrected need for glasses.
On the other hand, myopia (nearsightedness) means
the eyes are out of focus more for distance than for near. If a child is
very nearsighted, things will be blurry both at distance and at near.
Some children are extremely myopic (nearsighted) at a young age. By age 2
or 3, they will be sitting very close to the TV and holding objects up
close to their face. These children usually take readily to glasses and
like to wear them without much adjustment.
The most common form of nearsightedness, where vision is better at near than distance, does not begin until about ages 5 to 7 or sometimes later. Nearsightedness usually increases in amount every year as children grow, with the greatest changes occurring between ages 6 and 12, but many continue to become more nearsighted as teenagers. In general, the earlier the nearsightedness begins, the more nearsighted the child will become.
If a child is only slightly nearsighted, it may be best to avoid glasses and obtain another eye exam in 6-12 months. Children who see clearly at near but require glasses for small amounts of nearsightedness should remove them for reading or other close-up activities. However, children who are significantly myopic will need glasses for most or all activities.
In the past, dilating eye drops, bifocals or hard contact lenses have been used to treat nearsightedness; today only refractive surgery, such as LASIK, is the only type of therapy available to actually eliminate nearsightedness. These types of surgery are generally not done in children because their eyes have not yet finished growing. The eye normally stops growing by about 18 to 21 years of age. A few children have undergone these procedures, but most children’s nearsightedness is best treated with glasses or contact lenses.
The term astigmatism means that the eye is shaped oval like a football instead of the normal round shape like a basketball. Infants often have small or even moderate amounts of astigmatism that may simply disappear and need no treatment. Children, ages 1 to 3, who have large amounts of astigmatism will need to wear glasses. Others with only small amounts of astigmatism may not require glasses at all. Sometimes, the astigmatism goes away by itself, but other times, glasses are needed at an older age for reading and schoolwork. If the astigmatism is very large or greater in only one eye, glasses may be needed during all waking hours.
Glasses do not make astigmatism disappear, and they do not change the shape of the eye. Glasses only bend the incoming light to correct misshapen eyes. The eye undergoes natural slight changes in shape with age, and astigmatism may increase or decrease in amount depending on the growth of the eye.
Since the vision problems of children are far different from adults, a pediatric ophthalmologist is best qualified to determine a child’s need for glasses. A pediatric ophthalmologist is an Eye M.D. (an eye physician and surgeon) who specializes in children. A pediatric ophthalmologist graduated from medical school and completed a three or four-year approved ophthalmology residency program training in all aspects of eye disease. In addition, this type of physician received further training in an approved fellowship program dedicated to the study of eye diseases and disorders of children’s eyes such as hyperopia, myopia, astigmatism, strabismus and amblyopia. Pediatric ophthalmologists who are members of AAPOS have demonstrated high qualifications in the proper treatment and care of children’s eyes.
It is extremely important that children be prescribed the appropriate glasses so they will develop normal vision while they are still growing. Some children require glasses for all waking hours, while others whose eyes are only slightly out of focus may be best served by not wearing them at all. Children’s glasses can be very expensive, because a two year old could easily need new glasses every two to three months at $150 or more per pair. The skill of the eye examiner, combined with frequency and costs of glasses, should be considered when searching for the best person to examine a child’s vision.
Considering that the life expectancy of a child born today is probably about 90 years, an early eye exam or screening test is an excellent investment for life. Most parents will have already their child’s teeth checked by age 3 or 4. An eye exam for children is just as important, for unlike teeth, eyes cannot be replaced.
For more information, visit the AAPOS Web site at http://med-aapos.bu.edu.