Uncorrected vision problems, childhood literacy deficits linked

March 11, 2016
Study correlates uncorrected hyperopia with decreased performance on literacy test.

Children's near-vision isn't the only thing that suffers when hyperopia goes untreated; early literacy skills also lag with potential repercussions for grade-school readiness.

Published in late January in the journal Ophthalmology, the Results of the Vision in Preschoolers—Hyperopia in Preschoolers (VIP-HIP) study found that children with moderate hyperopia (3 to 6 diopters) performed "significantly worse on the Test of Preschool Early Literacy (TOPEL) than their normal-vision (emmetropic) peers."

The National Eye Institute-funded study examined 492 children, 4-5 years of age, finding a deficit between hyperopes and emmetropes especially pronounced in the TOPEL's print knowledge category that assesses children's ability to identify letters and written words. Hyperopic children with visual acuity of 20/40 or worse accounted for the largest deficits in TOPEL scores when compared to emmetropic children. While, overall, the mean difference between hyperopes and emmetropes measured -4.3 on the TOPEL.

Marjean Taylor Kulp, O.D., distinguished professor at The Ohio State University College of Optometry and VIP-HIP study lead author, says in an email that these differences are meaningful because formal learning for many children begins in the preschool years, making early detection crucial.

"Preschool children with moderate hyperopia and decreased near vision may, therefore, benefit from referral for assessment of early literacy skills," Dr. Kulp writes in an email.

Moderate hyperopia—farsightedness—only affects about 4-14% of preschool children, but can often go undiagnosed and uncorrected. That's because common vision screenings done in schools are generally ineffective in detecting hyperopia. Hyperopes have little difficulty identifying letters on an eye chart at distance, yet involuntarily exert extra effort to maintain clear vision on near work, often causing fatigue, tension and discomfort.

While easily missed in a vision screening, hyperopia can be effectively diagnosed in a comprehensive eye examination performed by an eye doctor, and can be corrected with glasses or contact lenses with little effect on lifestyle.

Reinforcing the importance of pediatric eye examinations

Although further research is needed to categorically determine whether early vision correction can prevent the literacy deficits highlighted in the VIP-HIP study, other studies have shown that early deficits in literacy are associated with future problems in learning to read and write. One such study found 66-74% of adults with literacy problems in its test group had failed vision screenings, while behavioral conditions affecting learning, such as attention deficit hyperactivity disorder (ADHD), also often correlate with vision impairment.

Good vision is key to development and scholastic success with as much as 80% of a child's learning occurring visually; the ability to see clearly affects everything from reading and writing in the classroom, to participation in sports and play. And because vision may change frequently during school years, regular eye and vision care is important.

Steven A. Loomis, O.D., AOA president, says the study further supports the need for comprehensive eye examinations for all children to optimize their chances for academic success.

"We welcome the results of the recent NEI study, which clearly shows the relationship between uncorrected refractive error and learning," Dr. Loomis says. "Naturally, these results come as no surprise to the profession of optometry, which has long advocated for access to eye and vision care for our children. It is especially important to note that the study dealt with hyperopia, the refractive error most often missed in school and pediatric vision screenings."

As children progress in school, they face increasing demands on their visual abilities. When certain visual skills have not developed, or are poorly developed, learning is difficult and stressful, and often children:

  • Avoid reading and other near visual work
  • Attempt to do the work anyway, but with a lowered level of comprehension or efficiency
  • Experience discomfort, fatigue and short attention span

The AOA recommends children receive an eye examination at least once every two years, and more frequently if specific problems or risk factors exist, or if recommended by the child's eye doctor. Vision screenings often administered in schools only test for distance visual acuity. Although a child may pass such a test, they can still have a vision problem that can go undetected unless caught in a comprehensive eye examination performed by an eye doctor.

Read more about the vision skills necessary for school success, as well as signs of eye and vision problems in children.

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