For Ann Zawistoski, handling news that her 1-year-old daughter had vision difficulties proved much more complicated than simply buying a pair of glasses.

"I felt this combination of being upset that there was something wrong with my child and a sense of guilt that I hadn't known there was a problem," says Ms. Zawistoski, an academic librarian in Northfield, Minn. "Then there was dealing with how to keep her glasses on."

Toddlers wearing glasses look adorable, but the cuteness can cause problems. Many children who are still getting used to glasses find wearing them brings unwanted and unrelenting attention. Some people may even accuse parents of putting fake glasses on their children to be trendy.

Glasses have a serious function, though, and sometimes they are crucial to normal development of a child's vision and brain. Eyeglasses can fix more than near or farsightedness and may address common conditions such as amblyopia, or "lazy eye," and eye misalignment. Sometimes doctors require children to wear an eye patch to teach the brain to use vision stimulation from the weaker eye rather than ignore it.

The number of preschool-aged children needing glasses is expected to rise as diagnostic tools improve and eye-health awareness increases, doctors say. In the U.S., as many as one in 20 preschool-aged children has a vision problem, according to a study published in 2011 in the journal Pediatrics.

More parents, meanwhile, find they have to navigate an unexpected flood of challenges, such as dealing with public scrutiny, explaining why beloved cartoon characters don't wear glasses and keeping the frames on their toddlers.

In some ways, growing up wearing glasses isn't much different than learning to put on soccer shin guards or carry a backpack to school. After the initial agitation of getting accustomed to wearing frames, young children often express relief and surprise that they can see better. The diagnosis is often emotionally charged for parents, who don't want a lifetime of challenges and potential teasing for their child.

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