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Why is regular vision screening so important?

Good vision is key to a child’s physical development, success in school and overall well-being. The vision system is not fully formed in babies and young children, and equal input from both eyes is necessary for the brain’s vision centers to develop normally. If a young child’s eyes cannot send clear images to the brain, his or her vision may become limited in ways that cannot be corrected later in life. But if problems are detected early, it is usually possible to treat them effectively.

Inspection of the eye, pupils and red reflex

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 should be 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.

Photoscreening

This is an automated technique incorporating a special camera which uses the red reflex to help identify risk factors for poor vision, such as refractive errors (the need for glasses) and other abnormalities in the eyes. It is fast and easy to learn and is now widely used in community group screenings. Information can be electronically submitted to a professional for interpretation if necessary.

Corneal light reflex testing

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.”

  Cover testing

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.

Visual acuity testing

The use of an eye chart requires a cooperative child, so successful testing is greatest with children 3 years and older. It is the only screening method that directly measures visual acuity, and is the preferred exam for older children. Modifications of the adult eye chart make it easier to test children. For example, it is recommended that the 20-foot testing distance be shortened to 10 feet.  Symbols or shapes can be used in place of letters. Testing with both eyes open initially is performed before carefully covering one eye at a time with a patch occlusion to test each eye separately. It is important to use a secure eye patch for testing individual eyes as young children are apt to “peek” especially if there is a difference in vision between the two eyes.

References

https://www.aao.org/eye-health/tips-prevention/children-eye-screening

https://www.aapos.org/terms/conditions/107

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