Farsightedness Associated With Literacy Problems in Preschoolers
Many young children have some degree of farsightedness—an ability to see objects far away more clearly than objects that are close up. Health providers are divided on whether moderate farsightedness even requires correction, with some arguing that children are able to compensate for moderate levels of distortion.
But a recent study found that children ages 4 to 5 with moderate farsightedness scored significantly worse on a test of preschool literacy—raising the question of whether eyeglasses might help make a difference. The research was funded by the National Eye Institute, a part of the National Institutes of Health.
Degrees of hyperopia, the medical term for farsightedness, are measured in positive diopters. Health practitioners generally agree that mild cases don't need correction because children often outgrow it, but a child with hyperopia over +6 diopters should be considered for glasses. Farsightedness is common in young children; a different NIH study found that about 21 percent of preschoolers have some degree of farsightedness, compared to 4 percent of preschoolers who are nearsighted, and 10 percent who have astigmatism, or an irregular curvature of the eye.
In the study "Uncorrected Hyperopia and Preschool Early Literacy," published online Jan. 27 in the journal Ophthalmology, researchers focused on farsighted children in the group where the recommendation for correction is not as clear-cut. The study looked at about 500 children, half of whom had normal vision and half of whom had +3 to +6 diopters of hyperopia.
The children were all given the Test of Preschool Early Literacy, which measures children's knowledge of print, vocabulary, and phonological awareness. The farsighted children scored lower than their peers with normal vision in all three parts of the test, but the largest gap was found in the print knowledge section, which tests children's ability to identify letters or words, as well as their ability to identify the sounds that letters make.
Moderate Hyperopia Should Prompt Literacy Evaluation
The study also found a range of ability among the farsighted children. The children who performed the worst on the test were at the higher end of the moderately farsighted range, at +4 to +6 diopters of hyperopia. The children who struggled the most also had problems with depth perception and binocular vision. The researchers hypothesized that farsighted children may be seeing intermittently blurry text, making it hard to learn the association between letters and the sounds they make. Other studies have shown a connection between farsightedness and reading problems in older children.
The study's findings don't necessarily mean that every young child who is farsighted should get glasses, said Marjean Taylor Kulp, a professor of optometry at Ohio State University and the lead author of the study. More research is underway to compare farsighted children who wear glasses to farsighted children who do not, to see if a literacy gap remains. But educators and parents should be aware of reading problems that can crop up in farsighted children, particularly because children who are early poor readers have a high likelihood of continuing to struggle throughout school. Young children are unlikely to complain about vision problems, Kulp said.
"For those kids who have that moderate farsightnedness, we would suggest they have their early literacy assessed," she said.