Vision screening is an efficient and cost-effective method to identify children with visual impairment or eye conditions that are likely to lead to visual impairment so that a referral can be made to an appropriate eye care professional for further evaluation and treatment.
There are a number of methods used to screen a child's vision. The method chosen is largely dependent on the age of the child being screened and the experience of the examiner. Several methods of vision screening are discussed below:
This method can be used on children of all ages. At each well child visit, the examiner uses a flashlight to inspect the eyes for abnormality of shape or structure and to detect irregularity in pupil shape. The pupil constricts (become smaller) in bright light and dilates (become larger) in the dark, and both pupils are the same size. An ophthalmoscope is used to observe the red reflex of the eye. The red reflex is a reflection from the lining of the inside of the eye that causes the pupil to look red in photographs. The red reflex should be bright in both eyes and equal.
This is an automated technique that uses the red reflex to identify many types of eye problems. An advantage of this screening is that it is quick and thus useful in very young children. The newest generation of photoscreeners provides immediate information about the eye condition. There may be an extra fee for this testing when performed at a doctor's office. Some community screenings use this method.
This simple test can be performed on any child using a penlight. As a child focuses on a penlight, the position of the light reflection from the front surface (cornea) of the eye is observed. The test is accurate only if the child looks directly at the light and not to the side. Normally the corneal light reflex is in sharp focus and centered on both pupils The test is abnormal if the corneal light reflex is not crisp and clear, or if it is "off-center."
This test detects misalignment of the eyes. While the child focuses on a target, the examiner covers each eye sequentially to look for a "shift" in the alignment of the eyes. This test requires a cooperative child (usually 3 years or older) and an experienced examiner.
The use of an eye chart requires a cooperative child, so successful testing is greatest with children 3 years and older. Since it is the only screening method that directly measures visual acuity, it is the preferred exam for older children. Modifications of the adult eye chart make it easier to test children. For example, the 20 foot testing distance is often shortened to 10 feet, and pictures or shapes can be used in place of letters. It is important to test each eye separately and to verify that the child is not "peeking" with the other eye.
The main goal of vision screening is to identify children who have or are at risk to develop amblyopia, which can lead to permanent visual impairment unless treated in early childhood. Other problems that can be detected by vision screening include strabismus, cataracts, glaucoma, refractive errors such as myopia ("nearsightedness"), hyperopia ("farsightedness") and astigmatism, ptosis and other more serious conditions such as tumors or neurological diseases.
Pediatricians, family practitioners, nurses and technicians can perform vision screening at regular well care office visits. In addition, many day care programs, churches, schools and health departments offer vision screening programs for children.
Vision screening is most effective when performed periodically throughout childhood. The earlier a problem is detected, the better the chance to obtain maximal vision through appropriate treatment. The first vision screening takes place in the nursery when the doctor or practitioner inspects the newborn's eye, pupil and red reflex. The child's practitioner continues to perform age appropriate vision screenings through infancy and childhood in addition to vision screening that is offered at day care, school or church.
In some states a documented vision screening or comprehensive eye examination is required before beginning school.
Vision screening is more efficient and cost effective (which allows many more children to be examined) than a complete examination on every child. Only about 2 to 4% of children have an eye problem that requires treatment, so it is not practical to perform a comprehensive eye examination on every child. In addition, some problems are missed on a one time comprehensive eye examination, so it is preferable to have several screenings performed over time. Also, mandated comprehensive eye examinations likely result in glasses being prescribed unnecessarily for many children.
Nevertheless, if a child has known risk factors for eye disease, if there is a family history of pediatric eye disease, or if a child has signs or symptoms suspicious for a vision problem, it is reasonable and appropriate for a child to have a comprehensive eye examination.
If a child fails a vision screening at any age, the child should be referred for a comprehensive eye examination. By age 3 or 4 years, most children are able to cooperate for subjective visual acuity testing using an eye chart. If a child is unable to cooperate for visual acuity testing at age 3, a second attempt should be made within 6 months, if the child is age 4, a second attempt should be made within one month. If retesting is impossible or inconclusive, then the child should be referred for a comprehensive eye examination.
An eye injury can occur at any time, in any place. Adequate prevention is important and could probably eliminate most eye injuries. Close to 50% of injuries occur in sports and recreational activities--more often in children and teens than any other age group.
Toys that are sharp are especially dangerous. Pencils, pens, darts, knives, fishing hooks, and scissors can easily penetrate the eye. Paint ball, pellet guns, and BB guns can cause very serious injuries. Fireworks are extremely dangerous to the eyes; children should never be allowed to use them.
Household items, such as forks, coat hangers, rubber bands, gardening tools, and kitchen gadgets can cause significant injury. Chemicals used around the home, like bleach, cleaning products, and even soaps, shampoos, and perfumes can cause extreme irritation and/or damage. Gardening tools and lawn mowers may propel rocks or particles toward the eyes. Acid from car batteries can explode, propelling chemical and particulate matter toward the eye. This can be especially dangerous when trying to "jump-start" a car. Safety glasses should be worn while working with potentially eye-damaging materials around the home, and children should be protected from exposure to vision-threatening situations.
Sports with high velocity ball action are potentially the most dangerous--racquetball, squash, tennis, soccer, golf, baseball, basketball, field hockey, lacrosse, water polo, and hockey.
Protective glasses or face shields are available for most sports. The best protective eyewear is a sports frame (not daily wear glasses) with polycarbonate lenses. If a child has a need for better vision with glasses, this prescription can be placed in the sports glasses. Although many athletes wear contact lenses, they do not provide protection against injury.
Children with poor vision in one eye should wear glasses for protection at all times. When participating in gym or sports, regulation sports glasses are necessary to protect the better-seeing eye.
If there is a chemical injury, immediate irrigation with water is critical. Flush the eyes and face with any available source of water for at least 10-15 minutes. Follow up immediately with a trip to the emergency room or ophthalmologist.
If a sharp object has penetrated the eye (like a fish hook), do not pull it out, but transport the person to the emergency room as soon as possible. Other blunt or sharp injuries should be examined by an ophthalmologist, since the serious nature of the injury may not be readily apparent.
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