A Vision Screening Is NOT Good Enough

by Marcia Dettloff, OD on September 27, 2010

OK.  I know school has already started but it’s never too late to get your child’s eyes examined.  Hardly a day goes by that a parent doesn’t tell me that their children have their eyes “examined” at school or at the pediatrician’s office.  The vast majority of these screenings only test distance vision.  While they are pretty good at picking up children with myopia (near-sightedness) or large amounts of astigmatism, those aren’t the children that are most important to identify and treat early.  Untreated myopia rarely causes permanent vision loss or learning problems.  Nearsighted children tend to excel in school because they see well up close so it’s easy for them to read and do near work.  Myopia also tends to develop during adolescence when children are older and can tell us that they’re having trouble seeing the board at school, reading the menu at Chik Fil-A or catching a baseball.

On the other hand, vision screenings frequently miss children with hyperopia (farsightedness) and strabismus (eye turn).  If not detected and treated early, preferably by age 5, these problems can lead to amblyopia (central vision loss in one eye) and/or prevent the development of stereoscopic 3D vision. Children with hyperopia are much more likely to have difficulty in school because of the extra concentration and effort required to see up close. Screenings also don’t catch more subtle problems with focusing or eye co-ordination that can contribute to learning difficulties.

When my children were in elementary school, I volunteered for the vision screenings and witnessed their shortcomings first hand.  Over the years I explained why the screenings were inadequate to the school nurse and any one else that would listen.  They probably thought I was just trying to drum up business.  After all, how could something as universal as the school eye test be so ineffectual?

Then one year a young girl came to the screening wearing a pair of glasses with a strong hyperopic prescription.  I called the school nurse over to watch her screening.  As I suspected, the girl could read the 20/20 line with each eye WITHOUT her glasses on.  To prove that her glasses weren’t just for reading, I had her try again with her glasses on.  She read the 20/20 line again.  Then I had the nurse try to read the chart while looking through the girl’s glasses.  She couldn’t even see the largest letters!  Some of the other parent volunteers looked through her glasses too, with the same result.  Everyone was stunned that this child passed the screening with flying colors without her glasses on.  I wish every parent could have seen that.

Unfortunately, even nearsighted children often slip through undetected. Many children will pass by squinting their eyes, peeking around the cover or remembering the letters they saw with the first eye.  I’ve seen school screenings were the whole class was lined up along the wall staring at the chart and/or hearing other children reading the letters out loud while waiting for their turn. I’ve had parents tell me their child had trouble reading the chart at the doctor’s office but they attributed the poor responses to the child being inattentive or uncooperative rather than having a vision problem.

Just this week, I had a 20-year-old patient come in for her first eye exam because she was having trouble seeing fine details on her art project at school.  She was a good student and hadn’t noticed problems with her vision in the past but she was significantly farsighted and had amblyopia in the left eye.  Even with glasses, she only has 20/30 vision in her left eye and she can’t appreciate 3 D.  Although extensive vision therapy may be able to treat these conditions even in adulthood, most patients aren’t willing or able to go through the effort and expense to do that.

There are far too many patients like this, or worse, that needlessly lose visual function and/or struggle in school because they have never had a comprehensive eye exam.  These are not just underprivileged children that don’t have access to care.  Many of them even have insurance coverage for eye exams.

The eye care professions have done a miserable job of educating parents about the importance of preventive eye care for children. Even children with significant vision problems frequently have no visual complaints.  The good eye covers for the bad eye and the child has always seen that way so it is “normal” to them.  Just as we don’t wait until our children’s teeth hurt to bring them to the dentist, we shouldn’t wait until they have visual complaints to bring them in for an eye examination.

As you can see from the following statistics, a significant number of children have vision problems that go undetected:

  • Up to 15% of children between the ages of 3 and 5 have an eye or vision condition that can result in reduced vision if not corrected.
  • 1/3 of pre-school children with significant eye or vision problems are missed even when licensed eye care providers perform more extensive screenings.
  • 25% of school-aged children have vision problems.
  • 80 % of  what children learn comes from visually processed information.
  • 60% of children identified as problems learners have undetected vision problems.
  • A study in 2000 found as many as 74% of adjudicated adolescents had undiagnosed vision problems.
  • In 2000, the state of Kentucky mandated eye exams for children entering kindergarten.  A study of the results of eye exams for the first year showed that 80 % of the children with vision problems had been to their primary physician the year before but less than 20% of them were told to have an eye exam.

For more information on the incidence and impact of undetected vision problems in children, please see this white paper by Joel Zaba, MA, OD in the Optometry Times.

Also see this 2004 Summary of Medical Literature on Vision Screenings and Eye Exams.

In my next blog post I’ll discuss how we examine preschool children.


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