Editor’s note: Ever wonder what the optometrist is looking at when she looks into your child’s eyes? Whether your child’s vision is up to par? Here’s a thorough look at children’s vision and vision exams from Kristina Tarczy-Hornoch, M.D., director of the Vision Development Institute at The Vision Center at Childrens Hospital of Los Angeles. The Vision Center is an international referral center for children afflicted with all forms of eye disease and provides both inpatient and outpatient services. It is the largest pediatric ophthalmology program in the nation.
Does your child have an eye problem that has gone undiagnosed?
Some parents, particularly those who are uninsured, may be tempted to wait until their child is examined under a school-district program. However, school screening sometimes leads to late diagnosis of vision problems, and may not identify all types of vision problems.
While your family physician or pediatrician can perform some basic parts of the eye exam, if you have any doubts about your child’s vision, you should obtain a comprehensive eye examination from either an ophthalmologist (a medical doctor specializing in diseases and surgeries of the eye) or an optometrist (an eye care provider with a degree in optometry). These vision specialists will have advanced tools and procedures to complete a thorough examination of your child’s eyes. Reasons to get a comprehensive eye exam include abnormal eye movements, crossed or drifting eyes, or failing to make or maintain eye contact at an early age.
Healthy vision is more than just the ability to see clearly, or having 20/20 eyesight. It is also the ability to understand and respond to what is seen. Young children should have basic visual skills including the ability to focus the eyes, use both eyes together as a team, and respond rapidly to visual stimuli.
What Happens At the Exam
For children of all ages, an eye doctor will conduct a physical examination of the eyes, inspecting the health of the structures at the front and back of the eyes. The doctor will test eye movements and eye alignment, to look for strabismus (also known as crossed eyes). The doctor will also test vision in different ways at different ages:
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- Preschool-age children do not know their letters in order to take standard vision tests. Eye doctors have charts for young children based on familiar picture symbols.
- For even younger children and infants, the eye doctor will test how the child tracks small objects, and whether he or she prefers using one eye over the other.
- For older children, your eye doctor may also perform a test of “stereopsis”, in which your child views specially designed images with glasses that show a separate image to each eye; this measures how well the two eyes are working together to produce depth perception. Children with strabismus, for example, may have decreased depth perception even though each eye can see well individually.
What is Retinoscopy?
The best way to tell whether a young child might need glasses is a technique called “retinoscopy,” in which the eye doctor shines a light into the eye to observe the reflection from the back of the eye (retina). By observing the reflection, the eye doctor can measure whether a child has significant amounts of any of the four main types of focusing problems that can be corrected with glasses:
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- myopia, or nearsightedness, in which the patient has difficulty seeing at a distance
- hyperopia, or farsightedness, in which the patient has to focus harder than normal at every distance in order to see clearly
- astigmatism, in which horizontal and vertical lines are never in focus at the same time
- anisometropia, in which the two eyes are never in focus at the same time
If a child needs glasses, the doctor determines the prescription (lens strength) from the retinoscopy measurements. In children who are too young to measure vision using picture or letter eye charts, the retinoscopy measurements are one of the most important indicators of whether vision is developing normally or not.
Dilating eye drops are an important part of most children’s eye exams for two reasons. First, without dilation, it is difficult to see the back of the eye in a young child. Second, dilation is necessary for accurate retinoscopy, because it relaxes the child’s own focusing, which would otherwise interfere with retinoscopy measurements.
What the Exam Can Detect
A complete eye exam can detect any of several common eye conditions in children, such as blurry vision, strabismus and amblyopia, a condition in which the child’s brain has developed a preference for one eye and ignores the other eye, usually because of strabismus and/or anisometropia. The exam can also pick up children who are at high risk for developing these conditions in the future. Be sure to tell your eye doctor if your child was born prematurely or if your family has a history of childhood eye problems.
Early diagnosis is crucial to effective treatment. Some of the more serious eye diseases like amblyopia and strabismus are correctable with various combinations of glasses, eye patching, blurring eye drops or surgery if caught early. Children born with strabismus who are not corrected within the first year or two of life may never develop depth perception. Amblyopia treatments work better in younger children than in older children, and don’t work at all in adults, so amblyopia that is not treated in childhood can lead to permanent vision problems.
If you child was prescribed corrective lenses, you need to be sure he wears them. Defeating the stereotype that glasses are unattractive is half the battle with school-aged children. If your child needs to wear glasses, you should allow the child to pick out the frames as it gives them a sense of ownership and pride. Learn more …
Tags: anisometropia, astigmatism, eye exams, hyperopia, myopia, retinoscopy, stereopsis
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