How astigmatism affects reading fluency

Excerpted from the April 2016 edition of AOA Focus, page 50.

Astigmatism causes blurred vision at any distance, so it's not surprising it has long been linked to decreased performance on low-level visual tasks. But the condition's effect on reading ability has been less scrutinized.

Now, a study by researchers at the University of Arizona has found astigmatism can affect a child's reading skills. The good news: Wearing glasses to correct the problem may boost reading fluency up to one-half grade level.

"This is one of the few studies in the vision science literature that shows that when glasses are needed for astigmatism, they improve oral reading fluency—they improve academic performance," says J. Daniel Twelker, O.D., Ph.D., one of the study authors and an associate professor in the Department of Ophthalmology and Vision Science at the University of Arizona.

The study, published in the February 2016 Optometry and Vision Science, included 273 students in third through eighth grade in schools on the Tohono O'odham Nation reservation, a group with a high prevalence of astigmatism. Based on vision testing, the students were categorized into three groups: those with high astigmatism in both eyes, moderate astigmatism in both eyes, and no or low astigmatism (defined as being less than or equal to one diopter), in both eyes. Glasses were prescribed to correct for blurred vision in the two groups of children with astigmatism.

Researchers assessed oral reading fluency in all three groups using a standardized test to measure speed and accuracy in reading brief passages out loud. They assessed children with astigmatism before and after the children received glasses.

With uncorrected vision, students in the high group showed significantly decreased oral reading fluency compared with the low/no and moderate astigmatism groups. Children with moderate astigmatism had reading fluency similar to those with no/low astigmatism.

After receiving glasses, high-astigmatism students boosted their accurate reading speed by almost seven words per minute—the approximate gain expected from one-half school year. Glasses had the most impact for older students reading smaller text, indicating that uncorrected astigmatism could have a significant negative effect on academic performance. Glasses had minimal or no effect on reading fluency for those with moderate astigmatism.

'Vision impacts learning'

The study provides "further evidence that getting the right pair of glasses for things like astigmatism is very important," says Ida Chung, O.D., assistant dean of learning, associate professor, in the College of Optometry at Western University of Health Sciences. "Vision impacts learning."

The children with moderate astigmatism may have shown greater improvement if some testing factors had been different, adds Dr. Chung. For example, she notes that the text size used was designed for students two grades lower than their current grade, perhaps falsely lessening the condition's negative effect in moderate cases.

The research highlights the importance of comprehensive eye and vision exams for children, says Dr. Twelker. "Especially for young school-age children, they won't know that they have astigmatism, even if it requires correction," he explains. "They're not going to generally come to a parent or a teacher and say that they can't see, draw or read at a grade-appropriate level."

(For children who are not otherwise at risk, the AOA recommends exams at 6 months, 3 years of age, before first grade and every two years after that because most children do not know that they aren't seeing correctly and don't know to say something.)

In contrast to comprehensive exams, vision-screening programs can miss problems, and give a false sense of security for those who "pass" but who in fact have issues, according to Dr. Chung. Comprehensive eye exams allow a doctor to provide continuing care and encourage spectacle compliance—a common problem—by talking with the children and their families about proper use and adherence, she says.

We want a relationship with the child's family and the doctor, so that the doctor can provide ongoing evaluations," Dr. Chung says.