I am frequently asked about glasses for children. Common questions include: "Should their eyes be tested?" (the answer is yes) and "should they get glasses or contacts?"

Dr. Sharon Freedman, a professor of opthalmology at Duke, tries to make sense of the glasses question for parents.

-- Dennis Clements MD, PhD, MPH

Sharon Freedman, MD

Eye glasses (also called spectacles), are commonly worn by adults, but their use by children often raises questions and causes confusion on the part of parents, educators, and the public at large.

The ABCs of Eye Glasses

Eye glasses help bend incoming light rays so that they are focused properly on the back layer of the eye (the retina). Adults wear glasses to see more clearly, but children wear glasses for a variety of reasons.

Glasses can correct some types of refractive error -- the problem that the eye has precisely focusing the incoming light rays on the retina. The main types of refractive error are called: myopia (near-sightedness), hyperopia (far-sightedness), and astigmatism.

Myopic eyes bend incoming light rays too much, usually because they are longer than the average eye. This causes near targets to appear clear, but distant targets are blurred. The solution is to place a concave lens over the eye to subtract refractive or bending power from the eye, and to move the eye’s near focus point to the distance.

Hyperopic eyes, by contrast, do not bend incoming light rays enough, often because they are shorter than the average eye. In hyperopic eyes, the target can only be placed in focus on the retina by adding extra power to the eye. This can be done either by placing a convex (magnifying) lens over the eye, or by thickening the lens of the eye (called accommodation).

The hyperopic eye has to work harder to see up close than it does far away, but young children and adults who still have the ability to change the shape of their lens (accommodation) can actually often see near and far even if they are hyperopic.

Eyes with astigmatism bend light slightly differently in one direction (or axis) than they do in another, usually because the front surface of the eye (the cornea) is just slightly oval rather than exactly round. Sometimes eyes with astigmatism also have myopia or hyperopia. All three of these common conditions can almost always be well corrected with spectacles.

Although most eyes that have a refractive error do not have a serious medical condition, sometimes eyes with a refractive error also have more serious coexisting problems, such as strabismus (misalignment of the eyes), amblyopia (lazy eye), or more rare conditions including cataracts (cloudy lens of the eye), glaucoma (high pressure inside the eyes), and retinal and optic nerve diseases (problems with the back layer or the nerve of the eye).

In these cases, the ophthalmologist will need to treat the serious eye condition and also will likely prescribe spectacles once the condition is under control.

Frequently Asked Questions

Why do children need glasses anyway?

Children wear glasses for four basic reasons:

• Correct a refractive error so that the incoming light rays will be properly focused on the retina and the eye will have the best possible image or vision
• Correct a refractive error that is worse in one eye than the other to help treat amblyopia (lazy eye)
• Help a child see clearly without having to focus (accommodate) hard enough that the eyes cross (usually this is true for hyperopic or far-sighted eyes)
• Help protect the eyes from injury, especially when one eye does not have good vision and the child would not be able to drive or conduct a normal visual life if something were to injure the better-seeing eye

How did the doctor know what glasses to prescribe for a baby or young child?

Fortunately there is a very easy way to determine the refractive error of any child’s eye, even one too young to provide feedback.

This process involves using special drops to relax the focus and dilate the pupil of the eye. A special machine or hand-held light and lenses can then be used to determine the actual refractive state of the eye, so that the eye care specialist (usually a pediatric ophthalmologist in the case of young children) can decide what spectacles, if any, are needed.

Not every child needs glasses, even if there is a small refractive error, and an ophthalmologist comfortable in the examination or care of children can determine whether or not glasses are needed.

My child squints and sits close to the television – does he/she need glasses?

Any child who frequently squints, closes one eye, holds his/her head in a consistent and unusual position, has a drift or misalignment of either eye, or has any visual complaint, definitely needs to have a full eye examination by an eye doctor comfortable with the care of children.

Most often the eyes are found to be normal, but these signs and symptoms can sometimes be the only evidence of a mild or even a more severe problem with the eyes that needs attention.

My child sees our pediatrician regularly -- does he/she need to have a separate eye examination anyway? And who should perform that eye examination?

Pediatricians regularly check each child’s eyes throughout infancy and childhood, beginning with the red reflex test right after birth. Vision screening occurs at the age of three or four years old and regularly after that time.

If the pediatrician does not feel that there is any problem with the eyes or the vision, and the parents agree, there is no need for a special eye examination. On the other hand, if the parents, teachers, or pediatrician feel that there is any issue that might be vision-related, it is very important to have a full eye examination, preferably by a pediatric ophthalmologist -- a medical doctor and surgeon specialized in children’s eye care.

In rural areas, an ophthalmologist (a medical doctor) or an optometrist (a non-physician eye doctor) can also do basic examinations on children’s eyes, but may refer to a pediatric ophthalmologist if a serious problem is found.

We have both worn glasses since childhood -- will our child need them, and at what age should he/she be examined to decide?

There is definitely a genetic component to most eye conditions, and refractive error is no exception. Parents who began wearing glasses in very early childhood should bring their young children for a full eye examination by the age of three years, or sooner if they or their pediatrician suspects any problem with vision, eye alignment, or eye appearance.

Children of a parent with a serious eye disease such as an eye tumor, cataract, childhood glaucoma, or other disease, should be seen in infancy by a pediatric ophthalmologist.

On the other hand, if parents began wearing glasses in middle childhood for myopia, the pediatrician’s vision screen is completely adequate to pick up a vision problem in childhood, and special eye examinations are probably not needed unless the pediatrician or family suspect a vision problem.

What happens if my child will not wear his/her glasses?

The consequence of not wearing glasses depends upon the reason for which they were prescribed in the first place.

For example, a young child who is given glasses to help treat amblyopia (lazy eye) or strabismus (crossed eyes) must usually wear these glasses during all waking hours for them to be maximally effective.

On the other hand, a child with mild myopia might need the glasses only during school hours to see the blackboard, but might be comfortable at home without them.

You should ask the ophthalmologist who prescribed the glasses exactly their purpose and how much they need to be worn. It is also important to be sure that the frame is properly fit to the child’s face, and that the spectacle has the correct power that was prescribed in each lens (sometimes the optical shop can make an error in grinding the lenses).

My child has a reading or learning problem, and “vision therapy” has been prescribed. Should we pursue the vision therapy?

All children with a possible or diagnosed reading or learning problem/disability need a full eye examination to rule out a correctable vision problem that might be making the reading/learning more difficult.

On the other hand, most learning disabilities are not related to vision or the eyes, but rather to the processing of the vision in the brain. Educational testing and special tutoring will be far more effective for the child than time and parental finances spent on vision therapy, which treats the eyes but not the visual processing problem.

Work with the pediatrician and the school system to maximally help the child with a suspected or diagnosed learning disability.

My child does not want to be seen in glasses -- can he/she wear contact lenses instead?

In young infants and children less than 11 years of age, contact lenses are usually only appropriate when a cataract has been removed from one or both eyes; however, for children who are 11-years-old or older, contact lenses are appropriate for the correction of refractive errors.

But before contact lenses can be used, the ophthalmologist must fully examine your child’s eyes to be sure contacts are medically safe, and then great care must be taken to be sure that the contact lenses are fitted and used by the child in a responsible and medically safe manner.

Every child wearing contact lenses in place of spectacles should still have a pair of properly-fitting, up-to-date glasses available for use when the contact lenses are not in the eyes. Contact lenses should usually be taken out of the child’s eyes daily.

How important are protective glasses for sports and recreational activities?

Accidental eye injuries continue to blind many eyes of children every day in this country, and most of these injuries are preventable.

Please take the time to purchase appropriate protective eyewear for children who are playing contact sports, especially for all children who have only one eye that sees well.

Protective eyewear is critical during games like paintball, and for children doing “shop” or other mechanical or automotive work.

How important are sunglasses for children?

It is clear that ultraviolet rays from the sun cause damage to our eyes that begins in childhood, but results in vision-threatening disease such as cataracts and age-related retinal disease only later in life.

Sunglasses or regular spectacles absorb most harmful ultraviolet rays and should be worn by all children when outdoors for any period of time.

How can I find out more about childhood eye diseases and about a pediatric ophthalmologist near my home?

The Web site for the American Association for Pediatric Ophthalmology and Strabismus (aapos.org) is a respected and very useful resource for this information.

-- Sharon F. Freedman, MD, is professor of ophthalmology and pediatrics at Duke.

-- Dennis Clements, MD, PhD, MPH, is the chief of primary care pediatrics at Duke Children's Hospital.