A vision test is a standardized examination used to evaluate and monitor a child’s vision and to detect potential diseases or disorders that may affect the eyes. A pediatrician, ophthalmologist (eye physician) or other trained eye specialist will regularly perform various tests of a child’s vision from the time a child is born until around the age of 5 years, with checkups every year or two years.

Vision problems affect more than 12 million children in the United States. Left untreated, these problems can lead to permanent vision loss, or to less serious but still substantial problems such as learning difficulties that may be attributed to a disability. Eye problems typically experienced by children include lazy eye, cross eyes and drooping of the upper eyelid (ptosis). Other eye problems may be caused by injury.

Preparation for a vision test is usually minimal, but parents are urged to inform their child’s physician regarding anything they may have noticed about the child’s behavior that may be related to a vision problem.

During a screening test, the examiner makes a visual check of the child’s eyes to look for signs of potential trouble. The screener uses a red reflex test to look for abnormalities in the back of the eye or cataracts or other clouding of the eye lens. The child’s visual acuity (ability to see over distances) and field of vision (entire area that can be seen at any one moment) are also tested.

A vision test is a standardized examination of a person’s eyes to look for signs of illness or disorder. It is the first step used to assess a child’s visual health. A vision test may be performed as part of a screening procedure, or as part of a full eye examination conducted by an ophthalmologist (eye physician).

Vision problems affect more than 12 million children in the United States. This includes 5 percent of preschoolers and 25 percent of school-aged children, according to the American Academy of Ophthalmology. Left untreated, these problems can lead to permanent vision loss. In other cases, eye conditions can cause less serious but still substantial problems such as learning difficulties. For example, children with impaired visual acuity (distance vision) often struggle to see the blackboard at school and their academic performance may suffer as a result.

Children should have their vision tested regularly as they grow up. Such screenings are crucial to detecting a condition early, when it is most treatable. Successful treatment of these conditions also can prevent children from experiencing developmental delays.

For most children, exams by an ophthalmologist, optometrist, pediatrician or other trained screener should be performed at the following ages, according to the American Academy of Ophthalmology:

• Newborn to 3 months of age
• 6 months to 1 year
• 3 years
• 5 years

Regular screenings should occur every year to two years. In some cases, children may need to be screened more frequently, especially for those at higher risk for eye disease. This includes those with a family history of eye problems or children who were born prematurely. According to the AAO, other risk factors that indicate a need for more frequent screenings include:

• Developmental delays
  
  
• People of African-American heritage, which increases the risk for glaucoma (high eyeball pressure that damages the optic nerve)
  
  
• History of previous serious eye injury
  
  
• Use of certain medications
  
  
• History of certain diseases, including diabetes or HIV infection

All newborn children should have their eyes screened before leaving the hospital. This examination will include an assessment of the general health of the eyes and a red reflex test, which screens for abnormalities at the back of the eye and conditions such as cataracts (clouding of the eye lens). Examination of the newborn can reveal eye problems that are present at birth, many of which are potentially serious threats to the child’s vision.

During the child’s first two years of life, a pediatrician will perform a basic visual examination during the child’s regular well-child visits. Initially, an infant’s vision is quite blurry, but begins to sharpen rapidly after about 6 months of age. Beginning at the age of 3 years, children are tested regularly to examine external functions (e.g., tear ducts, eyelashes), assess visual acuity (distance vision), and to check whether or not the child’s eyes are straight and how well they work together.

Types of vision tests given by a physician, typically an ophthalmologist, include a refraction test (to measure the eyes’ need for corrective lenses), visual field test (to check for gaps in the range of vision) and color vision test (to check the child’s ability to distinguish colors).

Conditions that may be detected in vision tests of children include:

• Lazy eye (amblyopia). This condition is the result of having crossed eyes or having a difference in refractive error (problem with the eye’s ability to bend light) between the two eyes. The test for amblyopia involves determining whether or not the eyes are straight and how well they work together. When caught early – especially by a child’s preschool years – lazy eye can be successfully treated. Left untreated, it can lead to permanent vision loss in the affected eye, as the brain will begin to ignore signals coming from that eye.
  
  
• Cross eyes (strabismus). A misalignment of the eyes that causes them to turn in, out, up or down. Placing a patch over the healthy eye can force the weaker eye to work harder, thereby strengthening it. Surgery or special glasses also are sometimes used to treat this condition.
  
  
• Drooping of the upper eyelid (ptosis). A condition caused by weakness of the muscle responsible for lifting the eyelid, damage to nerves associated with those muscles or looseness of the skin of the upper eyelids. It is often caused by an underlying condition that may be treated or the ptosis itself may be treated with surgery.
  
  
• Refractive problems. These occur when the shape of the eye does not properly bend (refract) light, causing blurring of sight. Examples include nearsightedness (poor distance vision), farsightedness (poor near vision) and astigmatism (imperfect curvature of the eye’s front surface). Refractive problems typically are treated with eye glasses or contact lenses.
  
  
• Color vision problems. A deficiency in seeing certain colors (e.g., shades of red or green). The condition is more common in boys and does not require treatment.
  
  
• Infantile cataracts. Clouding of the eye’s lens that sometimes occurs in newborns. Surgery typically is used to treat this condition.
  
  
• Congenital glaucoma. Rare, inherited form of glaucoma (high eyeball pressure that damages the optic nerve) that appears in newborns. Medications or surgery may be used to treat this condition.
  
  
• Retinoblastoma. Malignant (cancerous) tumor of the eye that usually appears by age 3. Laser surgery, radiation and chemotherapy are all used to treat this condition.
  
  
• Other genetic or metabolic eye diseases. These are conditions that make certain eye problems – such as retinoblastoma or cataracts – more likely. If genetic or metabolic eye diseases are detected, it is likely that the child will be required to undergo more frequent examinations.

When scheduling an appointment, parents are urged to avoid times of the day when their child tends to be especially irritable. Preparation for a vision test is usually minimal, but parents are urged to follow any preparatory recommendations made by the examiner. Parents can also prepare for the test by bringing along a toy or coloring book so the child will have something to do while waiting for the test. Prior to the vision test, parents are urged to discuss with their child’s physician anything they may have noticed about their child’s behavior that may be related to a vision problem.

During a screening test, the examiner performs a visual check of the child’s eyes to look for signs of potential trouble, such as tearing of the eye or eyelids that are swollen or crusted. The examiner also looks for more subtle signs of eye problems, such as a child’s tendency to squint, rub the eyes or tilt the head frequently. In addition, the screener may ask parents about any behaviors the child displays that may indicate a vision problem.

The screener uses a red reflex test to look for abnormalities in the back of the eye or cataracts or other clouding of the eye lens. During this test, the examiner holds an instrument called an ophthalmoscope about 12 to 18 inches (30 to 46 centimeters) from the child’s eyes. A reddish glow known as a red reflex should appear symmetrical in each eye. Signs that may indicate a problem include dark spots in the red reflex, blunted red reflex in one eye, complete lack of a red reflex or presence of a white reflex (resulting from a retinal reflection).

The screener also tests the child’s visual acuity, or ability to see over distances. There are many different tests used to measure this function. In infants, a bright-colored toy or other object will be held up and slowly moved to the left and the right while the examiner notes the child’s ability to follow the target.

In some cases, a human face, which is of greater interest to infants than objects, may be a superior “target.” An examiner moves his or her face and observes if the infant follows the face. The test may be repeated with the caregiver’s face.

By the time a child is in preschool, the “E test” will be used. In this test, the letter “E” is projected and the child points in the direction that the letter is pointing. By the time a child is age 5 or 6, a traditional Snellen acuity chart test can be used. This is the test that uses an eye chart with letters that grow smaller and smaller as one works down the chart. Children are asked to read the letters on the chart to the best of their ability.

A child’s visual field is also tested. This involves the entire area of space that the child can see at any one moment without moving the eyes, and includes peripheral vision. Several different techniques can be used to measure visual field. For example, the examiner may hold an object of interest (such as a toy) in each of the four quadrants of the visual field and observe to see when the child notices the object in peripheral vision. Or, a child sitting and looking at a screen with a target in the center may be asked to tell the examiner when an object becomes visible as it is slowly brought into the child’s field of vision.

Screening for lazy eye (amblyopia) is performed on children who are age 9 or younger. The screener determines if the eyes are straight and how well they work together.

Children who are too young to talk or who have other verbal challenges may be screened with a technique called photoscreening. A special camera is used to take a picture of the subject’s eyes, and a trained screener examines the photo closely for signs of vision problems.

Other tests that may be performed include:

• Tonometry test. Measures the fluid pressure inside the child’s eye through blowing a puff of air into the eye. This is used to detect glaucoma (abnormal buildup of pressure in the eye).
  
  
• Slit-lamp examination. Uses a low-power microscope combined with a high-intensity light source to provide a highly magnified view of the structures of the eye. The test can also be used to detect certain diseases that cause vision problems, such as neurofibromatosis.
  
  
• Titmus test. Tests binocular vision by displaying a series of three-dimensional images while the patient wears a set of Polaroid glasses. A child’s ability or inability to see these objects helps measure binocular vision.
  
  
• Color vision. Assesses a patient’s ability to distinguish colors. The ability to recognize patterns in multicolored dot charts reveals a deficiency or inability to see colors.

Once the vision test is complete, the reviewer assesses the information before making a recommendation. If the examiner is not an eye physician (ophthalmologist) and a potential problem is discovered, the child may be referred to an ophthalmologist for a full eye examination.

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Parents and children may wish to ask their doctor the following questions related to vision tests:

1. Who is the best person to test my child’s vision – a pediatrician, ophthalmologist or someone else?
   
   
2. How often should my child be tested?
   
   
3. Are there signs and symptoms that might indicate a vision problem in my child?
   
   
4. How should I prepare my child for the vision test?
   
   
5. What are some of the tests that will be performed?
   
   
6. What condition do you suspect my child has?
   
   
7. What are my child’s treatment options?
   
   
8. One of my child’s eyes wanders. Could this be a sign of vision problems?
   
   
9. Why has a slit-lamp examination been ordered for my child?
   
   
10. My child is 2 years old and has never had a vision test. Should he or she receive one?