By Stephanie Stahl

PHILADELPHIA (CBS) — Doctors say it’s not always obvious when children have trouble seeing, and that’s why it’s important that they get their eyes checked early.

For 7-year-old Peyton Gifis, visits to the eye doctor are now like clockwork.

When she was just 2-and-a-half years old, Peyton was diagnosed with a condition called strabismus, a misalignment in her right eye that forced it to turn inward and required corrective surgery.

“It was scary; it was definitely scary,” Devon Gifis, Peyton’s mother, said.

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Since then, Peyton has been getting annual, comprehensive eye exams, that go far beyond the simple eye chart test at school or in a pediatrician’s office.

“If a kid can read far away, they can usually pass those eye tests,” Dr. Saysha Blazier, an ophthalmologist, said. “But when it comes to reading up close, they may have major difficulties that are not detected. The words might look like they swim around on the page.”

A recent study published in JAMA Ophthalmology finds more than 174,000 preschoolers have vision impairment and the problem is growing.

“Every child should have an eye exam,” Dr. Blazier said. “The American Optometric Association recommends at six months, to get the first exam.”

“It now has just become one of those yearly examinations, rather than waiting for a problem – it’s now part of our every year routine,” Peyton’s mother said.

Peyton hasn’t had any issues since her surgery.

I’m happy that I don’t have to get glasses because I don’t want them,” Peyton said. And now she’s focusing on second grade.

Eye doctors say, if parents notice kids are holding a book too close, squinting or rubbing their eyes a lot, those may be signs of an eye problem that should get checked.