A growing number of US children may develop vision problems before they reach kindergarten, according to a study that suggests eye screenings will become increasingly important for the preschool set.

For the study, researchers analyzed data from US census records and from eye exams on about 12,000 children younger than 6 years. Nationwide, researchers estimated that more than 174,000 kids from 3 to 5 years old had vision impairment as of 2015 and projected that their ranks will swell by 26% to more than 220,000 by 2060.

Most of these kids have refractive errors that can be often be corrected with glasses.

This means parents should take kids for at least one comprehensive eye exam by age 3 and watch for signs of vision issues, said lead study author Dr. Rohit Varma, director of the Roski Eye Institute and dean at the Keck School of Medicine at the University of Southern California in Los Angeles.

"Parents should watch out for signs such as sitting close to the TV or holding a book too close, squinting, tilting their head, frequently rubbing their eyes, short attention span for the child's age, turning of an eye in or out, sensitivity to light, difficulty with eye–hand–body coordination when playing ball or bike riding, or avoiding coloring activities, puzzles and other detailed activities," Varma said by email.

"If children display such symptoms or behaviors then they should certainly get an eye examination," Varma added.

Hispanic children were most likely to have vision problems, the researchers report May 4th in JAMA Ophthalmology. As of 2015, Hispanic kids accounted for 38% of vision impairment cases, and researchers estimated this proportion would climb to this proportion would climb to 44% by 2060 aided by higher birth rates in this population relative to other racial and ethnic groups.

Based on changing demographics across the country, the second most–affected group is expected to shift from non–Hispanic white kids, who represented 26 percent of cases in 2015, dropping to 16.5 percent in 2060, to African American kids, representing 25 percent of cases in 2015 and 22 percent in 2060, according to the researchers.

The states projected to have the most children with vision impairment by 2060 are California, Texas and Florida, all of which have large Hispanic populations.

Overall, the types of vision problems found in children are projected to remain little changed by 2060, however.

Refractive errors will make up about 70% of cases by 2060, followed by amblyopia accounting for 24%. About 6% of cases will result from eye disease.

One limitation of the study is the reliance on census records with self–reported data on race and ethnicity, the authors note. Researchers also assumed the prevalence of impaired vision within different racial and ethnic groups would not change over time, so increases and decreases are based just on population changes.

Still, the findings should serve as a reminder to parents not to wait to get children's eyes checked until kids complain about their vision, said Dr. Janet Leasher of the Nova Southeastern University College of Optometry in Fort Lauderdale, Florida.

"Many children don't know that the way they see may not be normal, and the only way to find out is to have them assessed by a qualified eye care professional," Leasher, who wasn't involved in the study, said by email. "There are pediatric ophthalmologists and optometrists who specialize in children's vision, but any eye doctor can conduct the tests necessary to determine if there is a problem."