Study shows positive impact of mandatory preschool eye exams

Key Points

"Critics of mandatory preschool vision screening raise a number of objections, including questioning whether good vision is even necessary for learning," said Bisotti, a fourth-year student at the Indiana University School of Optometry, Indianapolis.

"In 2000, a law was passed in Kentucky requiring preschool examination and treatment but, to our knowledge, the only study investigating any effect of this law focused only on cost-benefit. Now, our research shows that compared with children unaffected by the mandatory preschool screening law, children receiving early vision care performed significantly better on standardized performance testing," Bisotti said.

Bisotti collaborated in this research with fellow fourth-year student, Joseph Bowling, BS, under the direction of Richard E. Meetz, OD, MS.

Focusing on results

Although it has been established that socioeconomic status affects standardized test performance, Bisotti and his coworkers were interested in investigating how that effect might be modified by the detection and correction of visual problems in preschool children. Bisotti explained that he and Bowling had a particular stake in this issue because they are Kentucky residents and plan to return to their home state to practice.

"Although 39 states require some preschool vision screening, Kentucky is one of only three states whose law requires a full eye examination with treatment and follow-up for any child who fails the test," Bisotti explained.

Data from the Kentucky Department of Education's Core Content Test, the standardized academic testing administered to public school children, was used as the academic performance endpoint. The focus was on reading scores and the total academic index for children in the fourth-grade. This is the first time the standardized testing is administered during elementary school.

The prelaw cohort, representing children not affected by the vision screening law, was comprised of children who took the Core Content Test during the years 2001 to 2003; the postlaw cohort represented children completing the Core Content Test in 2004 to 2006.

"The results from each year of testing are aggregated and available to the public on the Kentucky Department of Education Web site. Fortunately, for our study, the test content was virtually unchanged from 1998 to 2006," Bisotti noted.

Socioeconomic status was defined for each school district based on criteria previously established by Marshall and Dr. Meetz, which used county census data on median family income.

Comparing the data

In a statewide analysis, the mean scores for both reading and total academic index were significantly better for the postlaw cohort compared with the prelaw cohort. In further analysis with the data stratified on a year-by-year basis and the districts grouped by socioeconomic status, socioeconomic status had a statistically significant effect on test results in each year of the prelaw cohort. No effect of socioeconomic status, however, was present for any of the postlaw cohort years with regard to reading performance.

Additional post hoc testing showed the greatest improvement from the prelaw to the postlaw cohort occurred in the districts in the lowest socioeconomic status group, Bisotti reported.

The researchers acknowledge their epidemiological study is subject to a number of potential confounders. Its major limitation may be that an overwhelming majority of school districts in Kentucky, 156 of 176, fall into the lowest socioeconomic status group.

"The lower socioeconomic districts are receiving increased educational effort to improve reading performance. Despite that attention, there was still a significant improvement in test performance in the postlaw versus prelaw cohorts," he said.

"Since the only change between those time periods was the passage of the mandatory vision screening law, we feel our conclusion on its impact is solid. Ideally, however, it would be beneficial to have a larger number of districts in the upper socioeconomic levels, and we cannot rule out that children in these districts are already receiving previous care," Bisotti said.