"Negative attitudes appear to emerge at approximately 6 years and increase with age," write the Swiss researchers in the report of their study, published online in the British Journal of Ophthalmology.
In most cases, ''parents really should not wait longer than age 5 for surgery," researcher Daniel Stephane Mojon, MD, head of the department of strabismology and neuro-ophthalmology at Kantonsspital, St. Gallen, Switzerland, tells WebMD.
A U.S.-based expert says the study results are not surprising, but that there is good news. "Fortunately, strabismus is often a treatable condition," says James Plotnik, MD, a pediatric ophthalmologist in Scottsdale, Ariz., and a clinical correspondent for the American Academy of Ophthalmology, who reviewed the study for WebMD.
The study finding ''demonstrates another potential benefit of early intervention to align the eyes," Plotnik says.
Children With Strabismus: A Closer Look
Although research has found that adults with strabismus can be negatively affected psychologically, fewer studies have looked at children with the condition and how they are affected socially, according to the research team from the University of St. Gallen, University of Bern, and Kantonsspital.
Strabismus is common, Plotnik says, occurring in about 4% of children in the U.S. and sometimes also occurring later in life.
Crossed eyes is the most common form, Mojon says, although strabismus can describe eyes that turn outward, inward, up, or down.
Experts don't know the cause, but sometimes the condition is related to problems with the muscles that control eye movement.
The Swiss researchers gathered 118 children, ages 3 to 12, with an average age of 7, and showed them photographs of six identical twin pairs, half boys and half girls. The photos were digitally altered so that one child had misaligned eyes and a darker or lighter shirt.
The researchers asked the children which of the two ''twins'' they would invite to their birthday party. The children were asked to make a choice four different times, so that meant they could select the faces of up to four children with misaligned eyes.
How Strabismus Affects Children: Results
The children who were aged 6 and older were much less likely to invite a child with strabismus to their party.
Although only one of the 31 children aged 4 to 6 didn't select a single child with strabismus, 18 of the 48 children aged 6 to 8 did not.
None of the children aged 6 to 8 chose a child with strabismus all four times, but three of the children aged 4 to 6 did.
When asked if they noticed anything in particular about the twins, the percentage of kids who made specific comments about the eyes increased with age:
- 19% of kids aged 4 to 6 commented on eye alignment without being asked to pay attention to eyes.
- 48% of kids aged 6 to 8 commented on the eyes without being asked to notice eyes.
As to why the younger kids didn't notice as much, the researchers say those younger than age 4 tend to process faces differently, looking at them ''piecemeal'' rather than holistically. So they may not realize the two eyes are misaligned, as they don't look at them as part of a whole, but individually.
The study results match anecdotal reports, Mojon tells WebMD. "Many parents actually are telling us they are noticing that, around that age, the children start discriminating."
Bottom line? The Swiss researchers suggest corrective surgery for the misaligned eyes should be done before age 6, to fend off social problems. "It's really important now, with these results, not to do it later than age 5," Mojon says
How Strabismus Affects Children: Second Opinion
Plotnik agrees and says the psychological effects of having crossed eyes should not be minimized. "There have been many well-documented studies on adults that have shown misaligned eyes can be more than just a trivial psychological problem," Plotnik tells WebMD. "Strabismus in adults, when it is noticeable by others, can interfere with a person's self-image, be a source of ridicule, and can affect the way that individuals are perceived by others."
The effect in children has been less well studied, he says.
Eye muscle surgery, one way to correct the problem, has a good success rate, Plotnik says, although more than one surgery may be needed to achieve correction.